Polymers Coatings E-Book
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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
The explores the cutting-edge technology of polymer coatings. It discusses fundamentals, fabrication strategies, characterization techniques, and allied applications in fields such as corrosion, food, pharmaceutical, biomedical systems and electronics. It also discusses a few new innovative self-healing, antimicrobial and superhydrophobic polymer coatings. Current industrial applications and possible potential activities are also discussed.
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Veröffentlichungsjahr: 2020
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Table of Contents
Cover
Preface
1 Fabrication Methods for Polymer Coatings
1.1 Introduction
References
2 Fabrication Methods of Organic/Inorganic Nanocomposite Coatings
Abbreviations
2.1 Introduction
2.2 Fabrication Methods
2.3 Conclusions
References
3 Dry Powder Coating Techniques and Role of Force Controlling Agents in Aerosol
Abbreviations
3.1 Introduction
3.2 Dry Powder Coating
3.3 Dry Powder Coating Techniques
3.4 Analytical Techniques for Ensuring Coating Uniformity
3.5 Force Controlling Agents
3.6 Inhaler Device and Capsule Coating
3.7 Numerical Simulation
3.8 Conclusion
References
4 Superhydrophobic Polymer Coatings
Abbreviations
4.1 Introduction
4.2 Theoretical Background
4.3 Physical and Chemical Texturing
4.4 Development of Superhydrophobic Coatings With Nanoparticles
4.5 Transparent Superhydrophobic Coatings for Self-Cleaning Applications
4.6 Superhydrophobic Coatings With Additional Self-Cleaning Function
4.7 Summary and Outlook
References
5 Superhydrophobic Coatings Applications
5.1 Introduction
5.2 Step I
5.3 Step II
5.4 Conclusions and Summary
References
6 Adsorptive Polymer Coatings
6.1 Introduction
6.2 Types of Coatings
6.3 Polymer Coating
6.4 Types of Polymer Coating
6.5 Adsorptive Polymer Coating
6.6 Materials
6.7 Adsorptive Polymer Coating Techniques
6.8 Adsorptive Polymer Coating Applications
6.9 Future Perspectives
References
7 Polyurethane Coatings
7.1 Introduction
7.2 Chemistry of Polyurethane
7.3 Formulation of PU Coating
7.4 Applications of Polyurethane Coating
7.5 Advantages of Polyurethane Coating
7.6 New Innovations and Future of Polyurethane Coating
7.7 Conclusion
References
8 Electroactive Polymer Nanocomposite Coating
8.1 Introduction
8.2 Electroactive Polymer
8.3 Electroactive Polymer and Nanocomposite Coating
8.4 Applications of Electroactive Polymer Nanocomposite Coating
8.5 Future and Summary
References
9 Conducting Polymer Coatings for Corrosion Resistance in Electronic Materials
9.1 Introduction
9.2 Conducting Polymers
9.3 Conclusion
References
10 Polymer Coatings for Food Applications
10.1 Introduction
10.2 The Main Objectives of Coating Food Surfaces
10.3 Components of Edible Coatings
10.4 Application Methods of Edible Coating on Food Surface
10.5 Food Applications of Edible Coatings
10.6 Microencapsulation of Bioactive Components in Food Systems
10.7 Conclusions
References
11 Biopolymers as Edible Coating for Food: Recent Trends
11.1 Introduction
11.2 Need for Edible Coatings
11.3 Functions of Edible Coating
11.4 Materials Used for Making Edible Coating
11.5 Composite Coatings
11.6 Current Trends
11.7 Conclusion
References
12 Polymer Coatings for Pharmaceutical Applications
12.1 Introduction
12.2 Polymers for Coating Pharmaceuticals, A Historical Perspective
12.3 Types of Coatings Used on Pharmaceutical Drug Products
12.4 Mechanism of Drug Release through Coating Systems
12.5 Ideal Characteristics of Coating Polymers
12.6 Conclusion
References
13 Self-Healing Polymer Coatings
13.1 Introduction
13.2 Self-Healing: Introduction and Benefits
13.3 Summary of Progress in Self-Healing Coating Technology
13.4 Realistic Frameworks of Self-Healing Polymeric Coatings
13.5 Potential Historic Activity
13.6 Conclusions
References
14 Polymer Coatings for Biomedical Applications
14.1 Introduction
14.2 Applications in Tissue Engineering
14.3 Polymer Coating for Drug Delivery
14.4 Polymer Coating as Antimicrobial Surfaces
14.5 Conclusion
References
15 Antimicrobial Polymer Coating
15.1 Introduction
15.2 Mechanism of Action
15.3 Factor Affecting Activity of Antimicrobial
15.4 Medical Applications
15.5 Conclusion
References
16 Characterization Techniques for Polymer Coatings
16.1 Introduction
16.2 Polymer Coating
16.3 Technique for Coating
16.4 Types of Coating
16.5 Characterization of Coating System
16.6 Conclusion
References
17 Polymer Coatings for Corrosive Protection
17.1 Introduction
17.2 Basics of Corrosion
17.3 Conducting Polymer-Based Coatings for Protection Against Corrosion
17.4 Synthesis of Conducting Polymer Commonly Used in Protection Against Corrosion
17.5 Performance Improvement and Bulk Modifications of Conducting Polymers
17.6 Conducting Copolymer Composites and Nanocomposites
17.7 Summary of Conducting Polymers-Based Protective Coatings
17.8 Conclusions
References
18 Polymer Coating for Industrial Applications
18.1 Introduction
18.2 Polymer Coating in Oil and Gas Industry
18.3 Polymeric Coatings for Tribo-Technical Applications
18.4 Polymer Coating for Drug Delivery
18.5 Polymer Coating for Corrosion Protection
18.6 Polymer Coating for Antibacterial Activity
18.7 Polymer Coating for Micro Bit Storage
18.8 Polymer Coating for Micro Batteries
18.9 Polymer Coating for Biomedical Applications
18.10 Polymer Coating for Pipe Line Applications
18.11 Conclusions
References
19 Formulations for Polymer Coatings
19.1 Introduction
19.2 Film Coating
19.3 Functions of the Polymeric Coating
19.4 Polymeric-Coating Approaches to Targeted Colon Delivery
19.5 Natural Polymers Applications in Modified Release Dosage Forms
19.6 Application of Polymer Coating in Biomedicine
19.7 Pellet Coating (Film Coating and Dry Coating)
19.8 Conclusion
References
Index
End User License Agreement
List of Tables
Chapter 2
Table 2.1 Different polymer-based matrix materials.
Table 2.2 Different inorganic nano fillers used in nanocomposite coatings.
Table 2.3 Different organic nano fillers used in nanocomposite coatings.
Chapter 3
Table 3.1 Summary of DPC technologies with their important advantages and lim...
Table 3.2 Various Turbo rapid variable (TRV) process based dry powder formula...
Table 3.3 List of sophisticated analytical techniques for understanding dry p...
Table 3.4 Force controlling agents (FCA) [26].
Table 3.5 Summary of inhalation powders containing FCAs.
Table 3.6 Commercial DPIs products containing magnesium stearate.
Table 3.7 Summary of inhalation powders containing amino acids as FCAs.
Chapter 4
Table 4.1 Some characteristics of natural examples of hydrophobic surface [4]...
Chapter 7
Table 7.1 Advantages of PU components.
Chapter 8
Table 8.1 Electrochemical corrosion measurements of the materials [30]. Repro...
Chapter 10
Table 10.1 Applications of polymer-based edible coatings for improving the qu...
Table 10.2 Applications of polymer-based edible coatings for improving the qu...
Chapter 11
Table 11.1 Starch-based coating application on horticulture produce.
Table 11.2 Gum-based edible coatings of foods.
Table 11.3 Recent studies with application of plant proteins as potential coa...
Table 11.4 Recent application of wax as an edible coating.
Table 11.5 Recent studies on chitosan-based edible coatings.
Table 11.6 Recent literatures with the application of edible gelatin-coating.
Chapter 12
Table 12.1 Physical attributes of some commercial soluble and non-soluble coa...
Table 12.2 Characterization of some film coating polymers related to commerci...
Table 12.3 Physical attributes of some commercial gastro-resistant polymers.
Chapter 15
Table 15.1 Polymer medical device applications.
Table 15.2 Polymers performing the passive action.
Table 15.3 Passive polymers perform antimicrobial activity.
Chapter 17
Table 17.1 Chemical structure and conductivity of widely used for metal prote...
Table 17.2 Oxidants and their standard oxidation potential, E0, used by chemi...
Chapter 19
Table 19.1 Replacement or formation of interfaces with the type of wetting me...
Table 19.2 Process variables influencing the wetting mechanism.
Table 19.3 Different aqueous soluble polymers for protection and taste maskin...
Table 19.4 Entero-soluble cationic polymers for protection and taste masking.
Table 19.5 Enteric anionic polymers for protection and taste masking.
Table 19.6 Insoluble polymers used for protection and taste masking.
Table 19.7 Threshold pH with target site of GIT.
Table 19.8 List of polymers for the enteric purpose of several dosage forms.
Table 19.9 Major approaches for targeting colon drug delivery [63].
Table 19.10 Modified-release dosage forms based on modified chitosan.
Table 19.11 Biomedical applications of polymer coatings [72].
List of Illustrations
Chapter 1
Figure 1.1 Latex film formation stages [2].
Figure 1.2 Fabrication techniques for polymer coatings.
Figure 1.3 A coating specimen obtained by spin coating a small molecule in s...
Figure 1.4 Reaction pathway for production of metal oxides in the sol–gel [3...
Figure 1.5 Coating is produced by sol–gel method [37].
Chapter 2
Figure 2.1 Sequential stages of the dip-coating technique for thin film depo...
Figure 2.2 Principle of cold spray technique for preparation of nanocomposit...
Figure 2.3 Principle of chemical vapor deposition method.
Figure 2.4 Principle of physical vapor deposition method.
Figure 2.5 General schematic diagram of thermal spray coating processes.
Figure 2.6 Principle of electrodeposition method.
Figure 2.7 Principle of electroless coatings experimental setup.
Chapter 3
Figure 3.1 Graphical representation of dry powder coating modified after Dah...
Figure 3.2 Key features of magnesium stearate for dry powder coating [Figure...
Chapter 4
Figure 4.1 An increase trend of the number of research papers with title of ...
Figure 4.2 Schematic presentation of water droplet on the rigid surface: (a)...
Figure 4.3 Schematic image of a liquid drop on the surface by different mode...
Figure 4.4 The effect of surface microstructure on changing hydrophobic to s...
Figure 4.5 The micro and nano roughness is created on the metallic substrate...
Figure 4.6 Schematic presentation of self-cleaning surface: (a) normal and (...
Chapter 5
Figure 5.1 Investigation of the superhydrophobic coatings applications in tw...
Figure 5.2 Superhydrophobic coatings substrates and substances.
Figure 5.3 Superhydrophobic approach via chemical and physical techniques.
Figure 5.4 Superhydrophobic coatings applications.
Figure 5.5 Superhydrophobic coatings application in different situations.
Figure 5.6 Superhydrophobic coatings applications to prevent inappropriate p...
Figure 5.7 Superhydrophobic coatings application to clean up surfaces in dif...
Chapter 6
Figure 6.1 Various types of coatings.
Figure 6.2 Types of polymer coating.
Figure 6.3 Common materials for adsorptive polymer coating.
Figure 6.4 Adsorptive polymer coating techniques.
Figure 6.5 Spray coating technique on substrate.
Figure 6.6 Dip coating technique on solid object.
Figure 6.7 Spin coating on substrate.
Figure 6.8 Solution casting technique.
Figure 6.9 Blade coating technique on substrate.
Chapter 7
Figure 7.1 Representation of urethane linkage.
Figure 7.2 Reaction for the synthesis of polyurethane.
Figure 7.3 Chemical Structure of PPG.
Figure 7.4 Chemical Structure of HTPB.
Figure 7.5 Resonance structure of isocyanate groups.
Chapter 8
Figure 8.1 Schematic of synthesis of electroactive polyimide-TiO
2
[34]. Repr...
Figure 8.2 Schematic diagrams of (a) mechanism of CRS passivation by EPT coa...
Figure 8.3 Inhibition zone of chemically synthesized pure PEDOT: PSS, bio-hy...
Figure 8.4 Sketches of proposed changes in layer morphology during actuation...
Figure 8.5 Actuated strain vs. nanofiller content for PVDF/CNT and ITO coate...
Chapter 9
Figure 9.1 The photographs of corrosive electronic materials and removal pro...
Figure 9.2 Influence of pH for the corrosion.
Chapter 10
Figure 10.1 Whey protein-based edible coating protects the cashew nuts from ...
Figure 10.2 Uncoated and coated strawberries with chitosan-based coatings af...
Figure 10.3 Uncoated (left) and coated with carrageenan (right) fish fillets...
Figure 10.4 Water migration from the center of the food to its surface (a) a...
Figure 10.5 Different structures of microcapsules.
Figure 10.6 Extrusion process using a coaxial nozzle.
Figure 10.7 Experimental setup for electro-hydrodynamic atomization. Dry-ele...
Chapter 11
Figure 11.1 SEM micrographs of banana peel control (a) and coated (b) at 1,0...
Figure 11.2 Control, carnauba wax (CW) coated, carnauba wax-glycerol monlaur...
Figure 11.3 Amino Acid Skeleton of Gelatin.
Figure 11.4 Color profile of banana without coating (1a), with shellac coati...
Figure 11.5 Schematic representation of nanofiber application as coating (Ad...
Figure 11.6 Schematic representation of antibacterial composite coating of c...
Figure 11.7 Commercially available indicators; (a). Fresh-check
®
label;...
Chapter 13
Figure 13.1 Schematic view of crack-induced self-healing processes. (a) A cr...
Figure 13.2 F/C ratios at two different probe depths (4 and 8 nm) for thin s...
Figure 13.3 Schematic illustration of the coating morphology and the shape m...
Figure 13.4 Self-healing of anticorrosion coating on AA2024 doped by micro c...
Chapter 14
Figure 14.1 Natural polymers frequently used for coating.
Figure 14.2 Natural polymers frequently used for coating.
Chapter 15
Figure 15.1 Schematic representation of mechanism of action of polymers.
Chapter 16
Figure 16.1 A schematic representation of apparatus used for spray coating. ...
Figure 16.2 Schematic representation of assessment of water vapor permeabili...
Figure 16.3 A schematic representation of assessment of water vapor permeabi...
Figure 16.4 Schematic to quantify oxygen permeation for free films. Adopted ...
Figure 16.5 Schematic of butt adhesion test. Adopted from Ref. [11].
Chapter 17
Figure 17.1 Schematic representation of the corrosion cycle of metal alloy [...
Figure 17.2 Anodic and cathodic reaction.
Figure 17.3 Typical 3-electrode cell used for electrochemical polymerization...
Figure 17.4 SEM images of PANI particles at different magnifications (a) 1,0...
Figure 17.5 Different forms of conductive polymer-based protective coatings....
Chapter 18
Figure 18.1 Polymer coating on proppant [3].
Figure 18.2 Photographs of samples, (a) O1 tool steel disk and pin, (b) ATSP...
Figure 18.3 Experimental results of Stribeck curve analysis, (a) COF vs. sli...
Figure 18.4 UHMWPE-based polymer composite [18].
Figure 18.5 Multilayer coating for drug delivery [29].
Figure 18.6 PVS modified amine coated substrates [45].
Figure 18.7 Process flow chart: (a) Au-deposited SiO
2
/Si substrate; (b) ferr...
Figure 18.8 Scheme of (a) the method for the modification of G_GP substrate ...
Figure 18.9 Polymer coating for pipe lines [51].
Chapter 19
Figure 19.1 The surface tensions relevant, mechanism of film formation: (a) ...
Guide
Cover
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Scrivener Publishing
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Publishers at Scrivener
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Polymer Coatings
Technology and Applications
Edited by
Inamuddin, Rajender Boddula, Mohd Imran Ahamed and Abdullah M. Asiri
This edition first published 2020 by John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA and Scrivener Publishing LLC, 100 Cummings Center, Suite 541J, Beverly, MA 01915, USA© 2020 Scrivener Publishing LLCFor more information about Scrivener publications please visit www.scrivenerpublishing.com.
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Library of Congress Cataloging-in-Publication Data
ISBN 978-1-119-65499-5
Cover image: Pixabay.ComCover design by Russell Richardson
Preface
Polymer coatings are thin polymer films that are applied to flat surfaces or irregular objects. Protective and decorative layers can be served by these coatings. They can be used as functional coatings with corrosion inhibitors or for decorative purposes like in paints. Polymeric coatings are known to be made of organic materials. However, they may contain metallic or ceramic grains to enhance endurance, properties or appearance. Polymeric coatings can be obtained using natural and synthetic rubber, urethane, polyvinyl chloride, acrylic, epoxy, silicone, phenolic resins or nitrocellulose, etc. There is a wide range of fabrication methods to design and construct polymer-coated materials. Compared to conventional coatings, they offer efficient and cost-effective coatings, facile fabrication methods with excellent properties such as corrosion, wear, and heat resistance, higher mechanical strength, and additional benefits, including good chemical and blocking resistance, and excellent scratch/abrasion resistance. Besides which, high gloss to matt looks, soft-touch effect, no color chage after UV exposure, excellent adhesion on metal and plastics, short drying time, fast hardness development, and easy formulation are other advantages of these coatings. Polymer coatings have various applications in the field of painting, storage media, semiconductors, optical devices, fluorescent devices, etc., and interest in them has increased due to their applications in areas such as electronics, defense, aeronautical and automotive industries.
This edition of Polymer Coatings: Technology and Applications explores the cutting-edge technology of polymer coatings. It discusses fundamentals, fabrication strategies, characterization techniques, and allied applications in fields such as corrosion, food, pharmaceutical, biomedical systems and electronics. It also discusses a few new innovative self-healing, antimicrobial and superhydrophobic polymer coatings. Subsequently, current industrial applications and possible potential activities are also discussed. This book is an invaluable reference guide for engineers, professionals, students and faculty members working in areas such as coatings, polymer chemistry, and materials science and engineering. Based on thematic topics, this edition contains the following eighteen chapters:
Chapter 1 provides an up-to-date account of fabrication methods for polymer coatings from the basic science to the latest innovations. The techniques which are described and discussed include blade coating, dip coating, spray coating, thermal spray coating, pulsed laser deposition, plasma polymerization, flow coating, spin coating, sol-gel and grafting.
Chapter 2 includes the different fabrication methods of organic/inorganic coating, namely, sol-gel method, cold spray technique, chemical vapor deposition, physical vapor deposition, thermal spray coating, electroplating deposition and electroless deposition. The classification of different coating methods for various organic/inorganic matrices and nanofillers are reported in detail.
Chapter 3 describes various eco-friendly dry powder coating techniques explored in the formulation and development of dry powder inhalers. Additionally, the chapter also includes a segment detailing the process analytical technology techniques, force controlling agents, implications in inhaler device coating and use of computational fluid dynamics in coating technology.
Chapter 4 first introduces the growth of bioinspired superhydrophobic coatings. Then, several theoretical backgrounds are discussed briefly. Afterwards, various methods are considered relating to the importance of creating chemical and physical textures on the surface. Additionally, the development of superhydrophobic and self-cleaning coatings with added nanoparticles are also presented.
Chapter 5 first investigates the nature (substrate-substance) and applications of superhydrophobic coatings. Afterwards, superhydrophobic coating applications are divided into three major categories of restrictive attributes, self-cleaning and smart attributes. All applications of hydrophobic coatings which have been examined in several studies are discussed.
Chapter 6 provides a brief overview of adsorptive polymer coatings, their techniquesand a comprehensive comparison. Moreover, adsorptive polymer coating applications in various fields are also discussed. Furthermore, a future perspective of existing challenges provides a better direction and understanding for overcoming these challenges in coming days.
Chapter 7 deals with the formulations and chemistry of polyurethane (PU) coatings, and also provides an insight into the development of PU over the conventional coatings. A detailed discussion of the advantages of PU coatings and their future scope in industry is also presented.
Chapter 8 emphasizes a unique type of polymer coatings based on electroactive material. Fabrication, essential characteristics, and potential applications of electroactive polymer coatings are discussed.
Chapter 9 deals with the importance of conducting polymer coatings in the field of corrosion resistance.
Chapter 10 discusses the main objectives, materials and techniques used for encapsulating food components or coating food surfaces such as fruits and vegetables, meat and meat products, eggs, cheese, nuts, and fried food. Biopolymers including polysaccharides, proteins, and waxes are the main ingredients used for this purpose.
Chapter 11 discusses the scope of biopolymers as edible coating in food products. The chapter emphasizes the various types of raw materials used for preparing edible coating. The role of edible packaging in microbial spoilage, mechanical damage, and consumer acceptance of food is discussed along with its advantages and limitations and selection criteria as edible coating for different varieties of food products.
Chapter 12 addresses the wider aspects of pharmaceutical coatings using different types of polymers and their applications in the development and manufacturing of conventional and modified release drug delivery systems. A historical perspective on pharmaceutical coatings along with their physical attributes and characterization are also discussed, which will guide researchers and pharmaceutical manufacturers to their appropriate selection.
Chapter 13 summarizes the critical characteristics of self-healing polymeric coatings. Progress in existing self-healing coating methods and realistic frameworks of polymeric coatings are presented. Surface self-regeneration and anti-corrosive protective layer fractures are discussed. Issues related to the transition from laboratories to valid industrial application of these self-healing technologies are addressed.
Chapter 14 describes various methods that have revolutionized the role of this fascinating strategy in biological science especially in biomedical applications, notably infectious therapy, drug delivery system for therapeutic agent and protective layer for implants and biomedical devices. The major focus is given to some key applications which are trendsetting for surface functionalization of implants and biomedical materials.
Chapter 15 describes the role of polymers against various microorganisms such as bacteria, protozoans and fungi. These polymers mimic the action of antimicrobial peptides which are utilized by immune systems of such living organisms to kill the microorganism. The main purpose of antimicrobial coating is to combat antimicrobial resistance and infections.
Chapter 16 discusses in detail the various processes and techniques that are most commonly used for the coating of polymers which protect active pharmaceutical ingredient (API) against environmental hazards and bodily fluids, protecting the body from adverse effects of API and modifying the release of API.
Chapter 17 discusses the different conducting polymer coatings used over metal surfaces for corrosion protection along with the role of conducting polymers and various coating techniques. Additionally, this chapter summarizes the performance improvement and bulk modifications of conducting polymers and extensive studies on the protective coating of conductive polymer materials are discussed.
Chapter 18 presents extensive research studies reported by worldwide scientists and specialists in the area of polymer coatings for industrial applications. New and emerging industrial applications are discussed, including microsystems, oil and gas industries, electronics, biomedical systems, pipeline, automotive industries, micro bit storage systems, anti-corrosion and antibacterial coatings.
Chapter 19 discusses recent advancements in the usage of polymers for coating of different dosage forms such as tablets, capsules, implants, nanoparticles, and liposomes. Additionally, mechanisms of polymeric film formation and applications of polymer coatings in the different areas of biomedicine are clearly explained as are the application of different polymers in various coating functions.
Editors
Inamuddin
Rajender Boddula
Mohd Imran Ahamed
Abdullah M. Asiri
February 2019
1Fabrication Methods for Polymer Coatings
Hüsnügül Yilmaz Atay
İzmir Katip Çelebi University, Department of Material Science and Engineering, Çiğli İzmir, Turkey
AbstractPolymer coatings mean the top layer applied on any substance for purposes like protection and decoration. It is possible to apply to synthetic materials as well as metals and ceramics. They are resistant to high temperatures, such as up to about 280°C. The polymeric coating process comprises applying a polymeric material onto a supporting substrate and coating the substrate surface. Polymeric coatings can be obtained using natural and synthetic rubber, urethane, polyvinyl chloride, acrylic, epoxy, silicone, phenolic resins or nitrocellulose, etc. There are a wide range of fabrication methods to design and construct polymer-coated materials. In this chapter, the techniques are described and discussed including blade coating, spray coating, thermal spray coating, pulsed laser deposition, plasma polymerization, flow coating, spin coating, sol–gel, dip coating, and grafting. The key point is provided to highlight current methods and recent advances in polymer coating fabrication techniques.
Keywords: Polymer coatings, fabrication methods, blade coating, spray coating, thermal spray coating, pulsed laser deposition, plasma polymerization, flow coating, spin coating, sol–gel, dip coating, and grafting
1.1 Introduction
Polymer coatings are thin polymer films that are applied to flat surfaces or irregular objectives. Protective and decorative layers can be served by these coatings [1]. They can be functional coatings such as adhesives or photographic films. They can be used as corrosion inhibitors or for decorative purposes like paints. Moreover, for modifying the surfaces, they can be utilized such as paper coatings or hydrophobic coatings.
Polymeric coatings are known to be made of organic materials. However, they may contain metallic or ceramic grains to enhance endurance, property, or appearance [2]. They offer various properties and additional benefits, for instance, very good chemical resistance, very good blocking resistance, and excellent scratch and abrasion resistance. Besides, high gloss to matt looks, soft touch effect, noncoloring after UV exposure, excellent adhesion on metal and plastics, short drying time, fast hardness development, and easy formulation are other acquirements of those coatings [3].
In general, polymer coatings are architected to manufacture a film of a kind of polymer. The process should be as fast as possible. The thickness is typically 1–100 m. The type of coating method varies according to the thickness of the desired covering, the rheology of the running, and the velocity of the web [2].
1.1.1 Starting Liquid Types
Before passing through to the coating methods, it is better to explain starting liquid types to obtain an impermeable and indiscrete polymer coating deposit. Three different types of starting liquids can be used to achieve this output. These are indicated as: polymer solutions, monomer liquids, and polymer latexes [2].
1.1.1.1 Polymer Solutions
It is necessary to decrease the viscosity of the polymer to make it a stickable fluid. For this purpose, the polymer is decomposed in a dissolvent. The fluidity property of the solution is regulated by varying the amount of solvent in the solution. The resulting fluid is covered onto the substrate. The dissolvent should then be removed by a drying operation. The glass transition temperature of the dispersion rises with removal of the solvent. If the drying temperature is smaller than the glass transition temperature, the coating passes to the solid phase. However, when the drying temperature is higher than room temperature, it is seen that solidification or hardening continues during the cooling of the coating. On the other hand, some of the polymers can crystallize when the dissolvent is removed. While some are cooling, they form semi-crystalline final polymer coatings [2].
Generally, most polymers are insoluble in water and organic solvents are used for dissolution. The solvent is selected in terms of both its ability to dissolve the polymer and its influence on the drying step. Due to the need to add different additives and reduce the cost, it may be necessary to use more than one volatile solvent [2].
The use of coatings produced with polymer solution is favored as they can be applied to a wide variety of polymers at the processing site specifications and formulated according to adjustable properties to produce evaluated properties in the last product. The quantity of polymeric material soluble in a solvent is relatively small. The drying requirement therefore appears as a function of the unit thickness of the coating. On the other hand, there are environmental and safety concerns due to complications related to solvent use. Solvent recycling is another important problem. It is also another disadvantage that flammable solvents need to be captured by expensive driers [2].
1.1.1.2 Liquid Monomers
Many monomers have fluid properties at room temperature. Therefore, there is no need to decrease their flow resistance at the coating process temperature. Also, they can be covered directly without adding any dissolvent. Oligomeric precursors can be said to be in this category. Without the need for a drying operation, the monomer liquids are allowed to solidify by serial curing reactions. Meanwhile, the molecular weight of the covering material rises in the period from progression of curing to the formation of a solid polymer layer. Hardening reactions are initiated by exposing them to energetic sources, for instance, ultraviolet light or electron beams [2].
The most widely used and popular coating material is epoxy in the field. They are not monomers, yet they are formed by a chemical reaction of oligomeric resins with its hardeners. The liquids can also be produced with dissolvent to enhance interoperability. Acrylates as liquid monomers are widely used for ultraviolet curing [2].
Monomer fluids do not require much drying step because they contain very little solvent. Therefore, they are quite attractive ways for coatings. The final coating properties (e.g., density of crosslinking) can be managed at the curing stage using parameters such as temperature, ultraviolet density, or the resin chemistry. Nevertheless, in some cases, the materials used in functional polymer solution coatings may be less expensive than monomers and initiating agents. Besides, due to the high degree of crosslinking, the final product can sometimes be brittle [2].
1.1.1.3 Polymer Latex
A latex can be defined as the dissipation of polymeric grains in water. In the case of lower water solubility of the polymeric materials having functional properties, the latex paths supply an environmentally suitable solution for forming enduring covering. Grains varying in size from ~ 10 nm to 1 umm can be manufactured from various polymeric chemicals by emulsion polymerization. It is easy to use, especially because they are synthesized in dispersion form and can be stabilized in the process. For some special applications, latex may also be formulated with other phases, such as ceramic grains [2].
The drying of the latex suspensions appears to be slightly different from the drying of the hard colloidal grains. This process is known as “film formation” depicted in Figure 1.1. Because water is removed, the grains go into the “consolidation” step and become more concentrated in suspension. When the drop time is over, surface tension, capillary, and van der Waals forces begin to pull the grains toward each other. Those forces must be powerful sufficiently to allow the grains to flatten at the grain–grain contact points. Consequently, the pores between the particles become smaller. This stage is called “compression.” The final stage is the “union” stage. Here, the polymer chains boil the particles together and transcend the boundaries between the grains. With that process, a finalized covering is formed that lacks gaps that were once between the individual particles [2].
Water is a liquid medium that can be used in latex coatings. Thus, monomer and solvent may be an eco-friendly alternative to other coatings used. Various coatings, such as paints and varnishes, seem to start as latex dispersions. On the other hand, it is pricey to transport and purchase latexes as raw material on a commercial scale. Besides, drying of water is an operation that requires more energy [2–4].
Figure 1.1 Latex film formation stages [2].
1.1.2 Polymer Coating Methods
Coatings made of polymeric materials can provide many different surfaces: metallic, ceramic, or synthetic materials, using a number of different techniques [5]. They must adhere well to the substrate. They should also not be readily susceptible to moisture, salt, heat, or different kind of chemicals. Generally, the following properties are required for a good coating film [3]:
Water-based resins. Low- or zero-volatile organic compounds (VOC)
Very good stain and chemical resistance
Very good blocking resistance
Excellent scratch and abrasion resistance
High gloss to matt looks
Soft touch effect
Nonyellowing after UV exposure
Excellent adhesion on metal and plastics
Carbodiimides for 2K systems
Figure 1.2 Fabrication techniques for polymer coatings.
Short drying time, hence fast hardness development
Easy formulation
Applied coating methods can affect the product quality, and thus the coating methods are important to obtain desired properties. Different fabrication methods are demonstrated in Figure 1.2.
1.1.2.1 Blade Coating
The blade coating can be defined as a process in which a certain amount of covering material is applied to the underside and the excess is removed by a measuring blade to obtain the desired coating thickness [6, 7]. This coating method has several advantages for obtaining a good coating film. Homogeneity of the coating area, small amount of material waste, prevention of intermediate layer melting, roll-to-roll production compliance, and economic use of the material [8–10]. In this method, fast drying process will prevent the slowing of the manufacturing process by solvent annealing [10]. Control of the thickness can be adjusted by controlling manufacturing conditions such as sol concentration, blade gap, and blade covering velocity [8].
1.1.2.2 Spray Coating
Spray coating technique is a process method in which the printing material (ink) is constrained through a nozzle and thereby forming a thin aerosol [11]. In this process, the performance of polymer solar cells seems to be limited by certain disadvantages, for instance, isolated droplets, non-uniform surfaces, and holes at some points. Regarding the process parameters, the flow rate, the pressure, the substrate temperature, the density of the mixing dissolution, the spraying time, the distance between the sample, and the air brush can be listed [6].
1.1.2.2.1 Nozzle-to-Substrate Distance
The distance between the nozzle and the surface is considered to be one of the process parameters, since it has a big effect on the morphology of the deposited part in the spray coating. Many studies were performed to examine and achieve the best distance of the nozzle and surface for the active coating. Vak et al. [12] found three areas between the air brush nozzle and the substrates, which were “wet,” “intermediate,” and “dry.” They then concluded that the perfect linear control distance was in the “intermediate-region.” This result is described as the spray time function. Susanna et al. [13] observed that, with the same material, the deposited material remained wet when the distance between the sample and the air brush was less than 15 cm. They reported that they manufactured dry and powdered coatings over 20 cm from the substrate. In this study, the “intermediate” region was 17 cm.
1.1.2.2.2 Solvent and Mixed Solvents Effect
There are many different solvents used by scientists to investigate the effects of dissolvent on coating quality and efficiency, for example, chlorobenzene, dichlorobenzene, trichlorobenzene, p-xylene, toluene, etc. The choosing of solvent affects the choice of nozzle–substrate distance for achieving the suitable thickness and the covering morphology. It is therefore important in all spray coating methods. Fundamentally, the principle behind selecting a dissolvent should be to select a quick-drying dissolvent to inhibit droplets from redissolving the substrates. However, this velocity should not be high enough to permit a homogenous and pinhole-free coating to be formed [14].
Pin-hole thin films are not desirable in that those films impair the efficiency of the coating. The quantity of fluid sprayed on the surface must be higher than at least a threshold to produce films without pin-hole. In this way, it may be possible for the droplets placed on the surface to join into a fully wet region. [6].
1.1.2.2.3 Substrate Temperature and Annealing Treatment
Green et al. [15] conducted an extensive work examining the performance of spray-coated devices over the effect of annealing temperature. In this study, it was seen that the efficiency of the devices amended with annealing temperature. The change in the intensity of the short-circuit current causes this to happen. Lee et al. [16] showed that the morphological surfaces of spray-coated equipment were not affected by thermal annealing at a micrometer scale at 150°C. Though, conflicting results have been reported by Dang et al. [17]. It was found that annealing affected the morphological texture of the active regions of the rotary casting and improved toward phase separation.
1.1.2.3 Thermal Spray Coating
Thermal spraying can be defined as a method of improving the surface of a solid object. This method can be used to coat a variety of materials to supply resistance to abrasion, erosion, cavitation, corrosion, abrasion, or heat. It can also be applied to supply electrical conductivity or insulation, lubricity, high or low friction, victim wear, chemical resistance, and many other desired features [18].
The application area of thermal spray is very wide. Extending the life of new components and repairing and reconstructing worn or damaged components may be some of them. In general, all thermal spraying methods include the adhesion of little softened grains to a dirt-free and conditioned surface to form a well coating. The combination of thermal energy and kinetic energy results in the flattening of the particles on the surface and on top of one another, with the successive layers forming an adhesive coating. Some advantages of thermal spray are shown below [18]:
Metallurgical cold processing.
No heat input, no deterioration.
A mechanical bonding process required.
Many different materials can be sprayed such as: steels, stainless steels, nickel alloys, copper, bronzes, molybdenum, ceramics, tungsten carbides, etc.
Thickness can be applied between 100 and 750 microns, but more can be provided.
Line of sight process.
Some of different types of thermal spray methods are used in the industry. In flame spray method, gas and oxygen are used for melting the wires before spray process with compressed air. Powder spray uses acetylene and oxygen for softening or melting the powders with the gas flow accelerating the grains to the substrate. In arc spray method, direct current (DC) electrical power is used for melting the wires before spray operation with compressed air. Plasma spray uses electric arc in an inert gas for creating a plasma that can soften the spray powders. The gas stream can project the powder onto the substrate for low oxide situation. High velocity oxygen fuel (HVOF) can use an accelerated oxygen or fuel flame for softening the spray powders and projecting them onto the surface with high levels of kinetic energy. All of the five thermal sputtering processes described above can be used to amend the substrate properties. Thanks to these engineering coatings, properties such as improved wear resistance, thermal barriers, electrical and thermal conductivity, hard chrome exchange, and insulation can be obtained on the material surfaces [18].
1.1.2.4 Pulsed Laser Deposition
The word laser is an abbreviation of light magnification with excited radiation emission. It has precious unique features such as narrow frequency bandwidth, consistency, and elevated power density. Because the light beam is too dense, it may be possible for vaporizing the hardest and heat-resistant materials. In addition, it has features such as high precision, reliability, and spatial resolution. Therefore, it has utility in the processing of thin coatings for the materials modification, heat treatment of the material surface, welding, and micro-modeling industry [19, 20].
In view of the pulsed laser deposition principle, it is generally seen that a pulsed laser beam is focused on the surface of a solid material. Electromagnetic radiation is strongly absorbed by the solid surface, which allows quick evaporation of target materials. When the content of the vaporized materials is examined, it is seen that it consists of highly excited and ionized species [21].
The pulsed laser deposition technique makes it particularly easy to store materials with complex stoichiometry. Therefore, it has attracted great interest of late years. The coating of the YBa2Cu3O7 thin film, a superconductor, was the first such process. Since then, the material, which is particularly difficult to obtain by multi-element oxides, has been successfully applied with this technique. The main advantages of this technique are [21]:
Conceptually quite simple:
Using a laser beam to evaporate the target surface and produce a coating of the same content as the target.
Versatile:
A wide range of materials can be coated in different gases over a wide gas pressure range.
Cost-effective:
A single laser can work with multiple vacuum systems.
Fast:
Good quality products can be obtained in 10 or 15 min.
Scalable:
Scaling can be achieved by advancing complex oxides toward volume production.
1.1.2.5 Plasma Polymerization
Plasma polymerization can be described that, in this process, organic and inorganic polymers can be deposited from a monomer vapor using an electron beam, ultraviolet radiation, or radiation discharge [22]. For low pressure plasma coating, it is ensured that gas or liquid monomers are processed, which are polymerized under the action of plasma. In general, the coating thicknesses obtained are in the range of one micrometer. The adhesion of the coatings to the surface is quite good [23].
When it is examined to activate and degrease, the process is much more complex. For example, barrier coatings are produced in fuel tanks, scratch-resistant coatings in headlights, and hydrophobic coatings. There are three coating methods used in large-scale applications [23]: hydrophobic coatings, PTFE (polytetrafluoroethylene)-like coatings, and hydrophilic coatings.
Coating of metals by plasma polymerization allows various effects such as continuous activation and functional coatings for one to several weeks. Process parameters should be set to take into account the characteristics of some equipment, such as generator type and power, electrode assembly, and material properties of the workpiece.
Plastics can be simply coated by plasma polymerization. In this way, a scratch-resistant coating can be made to CDs and DVDs without damaging their quality. If the products have low friction, PTFE-like coatings can be used to increase this. It may also be possible to bind functional groups such as amino groups used for bioanalytical applications to the plastic surface.
The difficulty in coating materials such as glass and ceramics is to prepare the surface accordingly. Once this problem is solved, there is no other element to prevent the application of the coatings. Check the adhesion of the covering to the surface in all cases. Where “mismatch” occurs between the coating and the substrate material, it may be ensured that the intermediate layers are applied as a binder. It is known that textile materials are very well-coated in plasma. However, the difficulty here lies in the long-term protection of coatings against surfactants. If hydrophobic coating is desired, fluorine-containing gases or monomers may be used [22, 23].
1.1.2.6 Flow Coating
The flow coating technique is a suitable form of coating to form polymer coating thickness gradients in the submicron regime. The device has a fixed blade that is fixed in a gap above a moving stage. The height of this gap can vary from tens of microns to hundreds of microns. The surface to be covered is firmly fixed to the stage, and the grains of a polymer dissolution are deposited between the blade and the surface and compacted. Next, the blade is accelerated relative to the surface. In the flow coating technique, the polymer is drawn through the substrate under forces caused by capillary forces holding between the fixed blade and the substrate, and by friction on the same solution as the blade. This process is in principle similar to the other measured flows for instance dip coating and blade coating.
In the fluid coating process, the capillary forces ensure that the polymer dissolution is kept under the knife at the first state at zero speed. In progress of time, the volume gradually decreases because of the evaporation of the dissolvent from the edges. At lower speeds, frictional pull may cause material to escape under the blade, although the capillary forces are intended to hold the material between the surface and the blade. This material then dries by evaporation of the solvent and is left in the shape of a wet coating [24–26].
1.1.2.7 Spin Coating
The spin coating method is a very common technique for applying thin coatings to the surfaces. It is seen that this technique is used in many different industries and technology branches. The most significant benefit of spin coating is the ability to manufacture very smooth coatings quickly and easily. The thickness of these films can range from several nanometres to several microns. The use of spin coatings is particularly common in organic electronics and nanotechnology. This production is based on many methods that can be utilized in different semiconductor industries [27, 28].
1.1.2.7.1 General Theory
In the spin coating process, it can be expressed as applying the desired material by pouring it onto the surface of a substrate and coating it evenly along its surface as it rotates in a solvent (an “ink”) (Figure 1.3). As the coating liquid is dropped to the center of the target, the stage begins to rotate. As the rotation accelerates, the resulting centrifugal force allows the liquid to spread over the entire surface to form the coating layer. Factors such as the viscosity of the fluid, the rotational speed of the target, the acceleration of rotation, and the aeration that affect the drying rate affect the thickness of the film formed [29].
Figure 1.3 A coating specimen obtained by spin coating a small molecule in solution by using a static dispersion (A. Rotating stage. B. Target surface. C. Coating fluid.) [29].
1.1.2.7.2 Applications
Spin coatings can vary greatly when viewed as a field of application. They can be used to cover surfaces smaller than a few square millimeters used in the state of the art, as well as to flat panel TVs with a diameter of 1 m or more. When evaluated as a coating material, it is possible to coat substrates such as photoresists, insulators, organic semiconductors, synthetic metals, nanomaterials, metal and metal oxide precursors, transparent conductive oxides, and many other different materials.
1.1.2.7.3 Advantages and Limitations
Combined with a thin and homogeneous coating, the greatest advantage in the spin coating process can be shown as the simplicity and relative ease of installation of a process. The high air flow caused by the high rotational speeds causes rapid drying. This helps ensure high stability in macroscopic or nano-length scales.
A single substrate is used for spin coating. This is the limitation of this process. Therefore, the yield seems lower than roll-to-roll operations. Certain nanotechnologies require time for self-assembly and/or crystallization. Fast drying times in spin coating can therefore lead to poor performance.
1.1.2.7.4 Spin Speed
The current rotational speed ranges are important because they define the thickness range that can be obtained from a particular solution. By rotating the coating, it is possible to produce homogeneous films relatively easily from about 1000 rpm. However, high quality coatings can be obtained with caution up to 500 or 600 rpm and sometimes lower than this.
1.1.2.7.5 Coating Duration
In general, standard spin coatings allow the substrate to spin until the film is completely dry. However, the boiling point and vapor pressure of the dissolvent utilized, as well as the environmental parameters in which the extrusion coating is made, such as temperature and humidity, affect this. A spin coating time of 30 s is recommended as a starting point for most processes, since this is considered to be sufficient [28].
1.1.2.8 Sol–Gel
Sol–gel technology can be defined as the use of liquid solutions to produce solid films with a wide chemical composition structure on various substrates at relatively low temperatures. Sol–gel-coated coatings are very diverse in function, for example, electrical conductivity, superconductivity, ferroelectric behavior, corrosion resistance, selective barrier for wear resistance and gas permeability, etc. There are many interdependent or independent factors that determine the manufacturing and specialities of sol–gel coatings [30].
Historically, the first synthesis of silica gel goes back to 1846. However, it is seen that sol–gel chemistry has been comprehensively researched ever since the 1970s. In the sol–gel method, chemical reactions of the basic precursor, which is usually an organometallic compound, are used in alcoholic dissolutions. These reactions produce various inorganic networks that can be constituted from a metal alkoxide dissolution [31, 32].
The sol–gel method has three steps for the production of the latest metal oxide protocols: these are hydrolysis, condensation, and drying. The operation begins by subjecting the metallic precursor to rapid hydrolysis to manufacture the metal hydroxide solution. In the following step, condensation occurs, leading to the constitution of a three-dimensional gel. After drying the obtained gel, the product obtained can be quite easily transformed to Xerogel or Airgel depending on the drying mode. The structure of metal precursors and solvents in the sol–gel process has an effective role in metal oxide synthesis. The sol–gel method can be classified in two ways, depending on the nature of the solvent used: aqueous sol–gel and anhydrous sol– gel method. If water is used as the reaction media, the aqueous solution is the method. However, if organic solvent is utilized as the reaction media, it is called anhydrous sol–gel. Figure 1.4 shows the reaction steps used for the manufacturing of metal oxide nanostructures in the sol–gel technique [33, 34].
The production steps of a radar-absorbing covering material manufactured by the sol–gel coating technique are shown in Figure 1.5. In this study, barium hexaferrite particles were synthesized by sol–gel [35, 36]. The precursors used were barium nitrate (Ba (NO3) 2) and ferric citrate monohydrate (C6H5FeO7.H2O), chelating agent citric acid monohydrate (C6H8O7.H2O), and pH regulator ammonium hydroxide (NH40H). Firstly, the process began by dissolving the ferric citrate and barium nitrate separately in citric acid. Using a magnetic stirrer, the solutions were vigorously stirred until a clear dissolution was achieved. Ammonium hydroxide was inserted to the dissolution until the pH reached 7 to ensure homogeneous suspension and stable pH. Next, the dissolution was held in a water bath at 80°C for 15 h in air to remove the water slowly from the solution. In this way, a high-viscosity wet gel was obtained. The wet gel obtained to prepare the dry gel was kept in an oven at 180°C for 15 h. Finally, in the sintering step, sintering was first performed at 550°C for 6 h to evaporate the impurities of the dry gel. The process was then completed by sintering in a tube oven at 1000°C for 5 h [37, 38].
Figure 1.4 Reaction pathway for production of metal oxides in the sol–gel [33].
Figure 1.5 Coating is produced by sol–gel method [37].
1.1.2.9 Dip Coating
Immersion coating is considered one of the earliest mercantile available processes. The primitive patent in that field was given to Jenaer Glaswerk Schott in 1939 for sol–gel reproduced silica films [39, 40]. Today, it is seen that this technique is used for various applications such as sol–gel derived coatings, ferroelectrics, dielectrics, sensors and actuators, membranes, superconducting layers, protective coatings, and passivation layers. The process is described by three important technical steps:
Immersion and dwell time:
At this stage, it is ensured that the substrate is kept in the coating solution for sufficient wetting for sufficient interaction. For this purpose, the surface is immerged in the precursor dissolution at a stable rate and then allowed to stand for a certain period of time.
Deposition and drainage:
At this stage, film deposition is made. By pulling the substrate upward with a stable velocity, a thin precursor solution layer is retained. Excess fluid is discharged from the surface.
Evaporation:
The dissolvent vaporizes from the liquid in this step. The deposited thin film may be supported by heated drying.
This is the fluid that forms it. Heat treatment is then carried out to burn the residual organics. In addition, the heat treatment carried out in this step may provide to crystallize the functional oxides.
Although that covering technique appears to be quite simple, microscopic processes need to be understood in more detail during immersion coating to adapt the final coatings. There is an important connection between the construction of the dissolution or the formed sol and the microstructure of the deposited coating. This is the coating process that establishes the connection. In the standard operation, the substrate is drawn upright from the solution tank with a stable velocity [41]. With the movement of the moving substrate, the liquid is dragged through a mechanical boundary layer based on the current line [42].
The flux moving upward is compensated by evaporation. As a result, the position of the film and the film remain constant relative to the surface of the coating bath. Upon evaporation and discharge of the solvent, the film has an approximately wedge-like shape terminating in a drying line. The vapor–solid–solid three-phase limit herein is defined as the drying line. Above this line, the nonvolatile species form the deposited part, which may be exposed to further curing. After gradual concentration of the inorganic species by evaporation, agglomeration and gelation occur to formalize a kind of dry gel or xerogel layer. The process ends with the final drying [39].
1.1.2.10 Grafting
This method is a capable tool for achieving surface grafting, surface modification, and functionality of polymer brushes on a solid surface. The final functionalized polymer chains can be grafted onto the solid surface, which is referred to as grafting. This grafting reaction may proceed with surface polymerization. In this way, a thin polymer brush layer is formed on the solid surface, which adjudicates the surface features. By combining surface roughness with mixed brushes, interchangeable ultrahydrophobic surfaces can be obtained [43].
The composition of surfaces and interfaces has a very important status in determining the performance of the materials. For example, areas of critical importance include the control of surface and interface properties, colloid stabilization, adhesion, lubrication, rheology, immobilization of catalysts, and the production of multiphase materials [44]. In addition to these classic areas, surface modification has lately played an important role in bioengineering, nonlinear optics, (bio) sensors, nano patterning, molecular recognition, waveguides, and electronic microcircuit operations. Accumulation of surface-bound thin polymer layers with convenient physical and chemical features for optimizing surface properties is one of the first operations [45].
The process is due to the elevated surface density, the precise placement of the chain on the surface, and the easy and controllable insertion of polymer chains with prolonged durability of the grafted layers. The most important benefit is the fact that several different polymers are attached to the same substrate. Prevention of macro-phase separation is achieved by chemical grafting. The features of the coating are determined by the consolidation of particular functional components. Polymer brushes are formed when the linked polymer chains contacted to the solid substrate with a chain end reach a relatively high grafting density. This can be clearly noticeable from other grafted polymer layers. Because of the excluded volume effect, the brush-like layers are formed when the surface is completely coated with a comparatively dense grafted chain monolayer normally stretched to the support. Parameters such as graft density, chain length, and chemical content of the chains can control the brush features [43, 46].
References
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