Water-borne self-assembled polymer/nanoclay-based nacre-mimetics with superior mechanical and functional properties

  • Wasserbasierend, selbstorganisiernder Polymer/Schichtsilkat-Verbund zur Perlmuttmimetik mit herausragenden mechanischen und funktionellen Eigenschaften

Das, Paramita; Möller, Martin (Thesis advisor); Richtering, Walter (Thesis advisor)

Aachen (2016)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen, 2016

Abstract

This thesis deals with the preparation and characterization of water-borne self-assembled polymer/nanoclay-based nacre-mimetics with highly ordered layered nanostructure mimicking the brick-and-mortar structure of natural nacre using a simple, fast, and scalable approach. This work shows that superb control over the nanostructuration in nacre-mimetics is achieved via concentration-induced self-assembly of polymer-coated core/shell nanoplatelets. Those are decisive to predefine the length scales of the final nanocomposite and reach well-ordered alternating hard and soft layers during evaporation-induced self-assembly. The aim of this work is also to expand the material property profiles beyond mechanical performance and use new concepts to achieve multifunctionality, which is highly relevant for future technologies. Such multifunctional properties include fire and gas barrier properties, anisotropic thermal, electric or ionic conductivity with superior transparency. In this regards, two-dimensional (2D) clay nanosheets are among the most interesting building blocks to realize these outstanding challenges, due to their high interface, nanoscale dimensions and tunable aspect ratio. In this work, on one hand, synthetic nanoclays of widely varied sizes (25-3500 nm) are used as hard building blocks to advantage their benefits over several shortcomings arising from natural nanoclays, and to study the effect of nanoclay sizes on structure formation and mechanical properties of the nanocomposites. On the other hand, for sustainable alternative, renewable polymer like sodium carboxymethylcellulose (CMC) is used as a soft energy-dissipating phase replacing the petrochemical based polymers. Moreover, the preservation of mechanical properties at high humid condition is also shown by introducing ionic supramolecular bonds. This work also concentrates on implementing new concepts for multifunctional biomimetic materials including excellent gas barrier and fire-blocking properties, glass-like transparency, and printability. Furthermore, an application of nacre-inspired, hybrid brick-walls fire barrier coatings is also shown on textiles with amphiphobic and self-cleaning features.