Handbook of Nanoceramic and Nanocomposite Coatings and Materials

Abdel Salam Hamdy Makhlouf, Dieter Scharnweber

• Publisher: Butterworth-Heinemann
• Year: 2015
• Print ISBN:
  9780127999470
• eBook ISBN:
  9780444633828
• Topic: Technology & Engineering
• Subtopic: Electrical Engineering & Telecommunications
• Index: Technology & Engineering

In this new handbook, top researchers from around the world discuss recent academic and industrial advances in designing ceramic coatings and materials. They describe the role of nanotechnology in designing high performance nanoceramic coatings and materials in terms of the unique advantages that can be gained from the nano scale, including the latest techniques for the synthesis and processing of ceramic and composite coatings for different applications. - Focuses on the most advanced technologies for industry-oriented nano-ceramic and nano-composite coatings, including recent challenges for scaling up nano-based coatings in industry - Covers the latest evaluation methods for measuring coatings performance - Discusses novel approaches for improving the performance of ceramic and composite coatings and materials via nanotechnology - Provides the most recent and advanced techniques for surface characterization

Part 1

Synthetic Approaches

Chapter 1

Polymer-Based Matrix Composites

Sascha Heinemann Max Bergmann Center of Biomaterials and Institute for Materials Science, Technische Universität Dresden, Dresden, Germany

Abstract

Since monophasic materials often feature limited property profiles, the development of composites is gaining increasing interest. Especially the combination of organic polymer phases and inorganic mineral phases has been identified to bear large potential with respect to synergetic effects. The research field is based on evolutionary role models, which make use of widely abundant substances in the Earth's geosphere and biosphere, namely, the minerals such as calcium phosphate and silica and the polymer collagen. Foreseeing the advantages of their association, a large number of bioinspired collagen-calcium phosphates, silica-collagen composites, and three-component materials have been prepared and characterized in terms of structure-property relationships. This chapter presents the main characteristics of natural role models, the development of several types of composites, and the analysis of possibilities and limitations for application focused on the field of biomaterials for hard tissue substitution.

Keywords

Polymer

Mineral

Organic

Inorganic

Composites

Structure

Properties

Collagen

Calcium phosphate phases

Silica

Sol-gel

Contents

1. Introduction and Definitions 3

2. Conditions Determining Possibilities and Limitations 5

3. Naturally Occurring Composites 7

4. Artificial Mineral Composites 9

5. Artificial Polymer/Mineral Composites 12

5.1 Fiber spun polymers in polymer/mineral composites 15

6. Conclusion 20

References 21

1 Introduction and Definitions

In the last years of research and development in the fields of technical materials and especially biomaterials, it has become obvious that a wide range of demanding applications cannot be satisfied by conventional monophasic materials although they are well established for several applications. Based on findings that defined mixtures show combinations of materials properties to be more useful than monophases, the development of composites was strongly established. In general, a composite provides improved specific or synergistic characteristics not obtainable by any of the original phases alone. The first composites were generated in constructional and technical materials science. With some delay, composites found their way also into biomedical materials research. There is no universal accepted definition of the term composite. However, in the field of biomaterials, the statements commonly include (i) combinations of two or more heterogeneous materials, (ii) multiphase materials built up from a single phase that differ in composition and form, and (iii) phases retaining their identities and specific properties while forming an interface between each other [1,2].

There are several ways of classifying composites, which will be presented in the following lines. Most of the composites consist of a structural phase (mostly inorganic particles, whiskers, fibers, lamellae, or meshes), embedded in a continuous matrix phase (mostly an organic substance). The function of the structural phase is usually to improve the strength of the composite, whereas the matrix phase acts as a binder for the inorganic building blocks and can provide elasticity and ductility. From a structural point of view, four types of composites can be distinguished: (i) fibrous (fibers in a matrix), (ii) laminar (layers of phases), (iii) particulate (particles or flakes in a matrix), and (iv) hybrids that represent combinations of any of the above three types. Literature related to biomaterials often makes use of the term hybrid or hybrid material instead of the term composite, which should not be mixed up with the above definition. In general, hybrid means that two phases are blended on the molecular scale while being characterized by the nature of the phases, interactions between the phases, and the resulting structure. When considering the nature of the matrix, crystalline/amorphous or organic/inorganic combinations are common. Building blocks can be molecules, macromolecules, particles, or fibers. Inorganic phases are mostly formed in situ by molecular precursors that often tend to form clusters or particles potentially templated by an organic phase. Based on the bonding characteristics, two classes of such hybrids can be defined [2]: Class I hybrids exhibit weak interactions between the phases caused by van der Waals forces, hydrogen bonds, and weak electrostatic interactions. An example is organic polymers with an entrapped inorganic phase lacking a strong interaction. Weak cross-linking can occur by the inorganic moieties or by the polymer matrix. When the inorganic phase forms its own network, additionally to the network of the organic phase, the term interpenetrating polymer networks is used. An example for that situation is the formation of an inorganic sol-gel phase in the presence of an organic network-forming phase. On the other hand, class II hybrids exhibit strong chemical interactions between the phases. In these cases, mostly discrete building blocks or polymers are linked to each other by forming covalent bonds.

Decreasing the total size of the building blocks—of the incorporated phase and of the matrix phase—and especially matching the sizes of the components to a common level drastically enhance the homogeneity of the composite and the range of adjustable properties. Especially, mechanical strength (tension, compression, and bending), often being a predominant characteristic of the material, can be dramatically improved by following this route [3]. In detail, improved characteristics mainly result from increased specific surface area and therefore enhanced interface area and cohesion between the phases. Based on this strategy, building blocks most frequently are of nanometer size, which means that at least one dimension of the basic unit is ≤ 100 nm. If these criteria are fulfilled, the composite can be termed a nanocomposite [4]. Since this group and the above hybrid materials make use of building blocks ranging in the nanometer size, the terms nanocomposites and nanohybrids are not clearly discriminated and often used as synonyms in the literature. Last but not least, the expression hybrid nanocomposite is valid and should be used for combinations of several individual nanocomposites for...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• About the Editors
• Contributors
• Part 1: Synthetic Approaches
• Part 2: Analysis and Property Profiles
• Part 3: Application Fields
• Index