From Sol-Gel Processing to Bio-Inspired Materials Synthesis

Abstract

The improvement of materials performance and their respective processing routes ever has been the driving force for material science and engineering. For the preparation of non-metallic inorganic materials the synthesis from chemical precursors is a field of steadily increasing scientific and industrial importance: Products in a broad variety of compositions can be obtained by sol-gel techniques. The shaping of intermediates allows the specific preparation of many microarchitectural configurations such as powders, fibers, thin films and aerogels. For purely inorganic products the sintering temperatures are low compared to conventional mixed-oxide ceramic processing which enables e.g. the coating of glasses and metals. Hybrid inorganic-organic compositions combine some advantages of polymers and ceramics.Nature has found amazing alternative ways to produce high-performance inorganic-organic composites at ambient temperatures under physiological conditions: Teeth, bone and nacre are self-evident examples for the capability of biomineralization processes.Even though many aspects of the related mechanisms in vivo are not yet fully understood, the utilization of the basic strategies of natural biomineralization has become a challenge to material scientist in an interdisciplinary approach.In this paper the strong points of sol-gel processing are highlighted, its limitations are discussed and related to the unique characteristics of natural biomineralization. Subsequently biomimetic and biologically-inspired material syntheses routes are reviewed which try to compensate the shortcomings of sol-gel techniques.

The toughening mechanism of nacre and structural materials inspired by nacre

“…Although the toughening mechanism of nacre is not yet fully understood, nanolaminar composites inspired by nacre have been fabricated in a variety of ways [102][103][104][105]. In this section, we briefly introduce the classification and principles of the fabrication methods and provide typical examples, paying particular attention to works in which the mechanical properties of the fabricated composites have been evaluated.…”

Challenges for Natural Monomers and Polymers: Novel Design Strategies and Engineering to Develop Advanced Polymers

“…Recent advances have been made in the development of synthetic proteins for novel applications. Insight into the structures of some of nature's most intriguing materials, such as diatom frustules, has revealed a major role for proteins in facilitating and templating inorganic composites, resulting in the development of bio-inspired materials [113][114][115][116].…”

“…Teeth, bone and nacre are self-evident examples for the capability of biomineralization processes. Even though many aspects of the related mechanisms in vivo are not yet fully understood, the utilization of the basic strategies of natural biomineralization has become a challenge to material scientists in an interdisciplinary approach starting from the sol-gel processing to bio-inspired materials synthesis [116]. Recent progress indicates that it is possible to control morphologies of all inorganic crystals and hybrid structures by choosing a proper molecular template, a solid matrix, suitable reaction micro-environments and appropriate self-assembly mechanisms.…”

“…Recent progress indicates that it is possible to control morphologies of all inorganic crystals and hybrid structures by choosing a proper molecular template, a solid matrix, suitable reaction micro-environments and appropriate self-assembly mechanisms. These materials with controllable length scale and complex form may have potential applications in various fields [116,117].…”

Synthesis of easily shaped ordered mesoporous titanium-containing silica

“…By comparison, as-prepared oxides (before calcination) which possess plenty of surface hydroxyl groups can be easily shaped without the assistance of additives. 1,2 Metal-containing mesoporous silicates are widely used catalysts in water and gas purification. Incorporated metal ions in the silica matrix can introduce acidic, ion-exchange and catalytically active sites, [3][4][5][6][7][8][9][10][11] showing advantages in treating hazards in water, for example, wet oxidation of phenol in water on Fe-containing mesoporous silica.…”