both polystyrene-and poly(methyl methacrylate)-grafted silica nanoparticles and produced a material consisting only of particles and surface-tethered polymer chains. They could observe a dependency of the materials Young's modulus, fracture toughness, and hardness on the degree of polymerization (DP) of the grafted polymer. [8] Crucial for the successful preparation of such materials is the presence of interactions between different particles through entanglement of polymer chains bound to different particles. This is given if the chains are long enough to entangle with each other or if the chains are cross-linked. [6] Additionally, research strives for achieving an order of the particles as it is hoped to produce materials with, for example, superior optical properties. [6,8] One naturally occurring "matrix-free" material with exceptional mechanical properties is nacre, which consists of 95 vol.-% of aragonite platelets and 5 vol.-% of organic biopoly mer. [9] They form a composite with a "brick-and-mortar"-like structure, which exhibits exceptional mechanical properties. The Young's modulus is known to be up to 135 GPa accompanied by a fracture toughness of up to 1.8 MJ m −3 . These properties can be assigned to the unique structure of this special material. [9,10] A biomimetic approach to produce a similar synthetic material is the use of layered nanoparticles, substituting the aragonite, and synthetic organic molecules to replace the natural biopolymer. Different nanoparticles, such as graphene oxide, [11,12] Al 2 O 3 platelets, [13] or nanoclays [4,10,14,15] have been used so far.In this publication, we report the successful preparation of a nacre-like material using montmorillonite (MMT) nanosheets and for the first time PMA to form self-standing films and explore new strategies to tailor their mechanical properties by modifying the polymer functionalization of the platelets. Using the soft and ductile PMA allows for the formation of nanocomposites that show an exceptionally high modulus and tensile strength without being brittle. The mechanical properties of the novel material are further enhanced by cross-linking of the surface-grafted polymer, which is either achieved via radical addition-fragmentation chain transfer (RAFT) star-polymerization upon the platelet surface or via introducing hydrogen-bonding moieties to the surface-grafted polymer. Matrix-free nanocomposite films of poly(methyl acrylate) (PMA) and montmorillonite (MMT) nanosheets that imitate the microscopic structure of nacre are developed and their mechanical properties are studied in detail via tensile testing. The exfoliated MMT nanosheets are grafted with PMA via a grafting-through radical addition-fragmentation chain transfer polymerization in presence of a surface-anchored ionic monomer. The mechanical properties are precisely tailored a) via the variation of the degree of polymerization of the surface-grafted polymer, illustrating the impact of chain entanglement and the MMT content on the performance of the material, and b) via cros...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.