Strategies for the Synthesis of Thermoplastic Polymer Nanocomposite Materials with High Inorganic Filling Fraction

Abstract

The governing parameters controlling the miscibility of particle additives within polymeric host media are analyzed for the particular case of silica particle fillers embedded within a poly(methyl methacrylate) (PMMA) matrix. For athermal polymer-graft modification of particles (corresponding to equal chemical composition of graft and matrix polymer), compatibility is found to be a sensitive function of the degree of polymerization of graft and host polymer chains as well as the particle radius. In agreement with theoretical predictions, uniform particle dispersion is observed if the degree of polymerization of grafted chains is comparable to (or exceeds) the corresponding value of the polymer matrix. The resulting restriction to high degree of polymerization limits the accessible inorganic fraction that is attainable in athermal particle/polymer blends. In contrast, favorable interaction between grafted polymer chains and the polymeric host (as realized in the case of poly(styrene-r-acrylonitrile)-grafted particles embedded within PMMA matrix) is shown to facilitate thermodynamically stable and uniform particle dispersion across the entire compositional range even in the limit of large particle size, short grafted chains, and high molecular matrix chains. The synthesis of thermoplastic composite materials with inorganic fraction exceeding 50 vol % combining quantitative optical limiting within the UV frequency range and polymer-like mechanical properties is demonstrated.

Supermolecular structure and nucleation ability of polylactide-based composites with silica/lignin hybrid fillers

“…Inorganic fillers such as silica are attractive reinforcements that are able to significantly improve thermal, mechanical and also chemical properties of PLA-based biocomposites [4,5]. Its valuable physicochemical properties along with high surface are the reasons for its widespread use [22,23]. Silica exhibits also a great potential for surface functionalization in terms of physical and chemical features and therefore gains even more possible applications [24][25][26][27][28][29][30].…”

Polymer-Tethered Nanoparticle Materials—An Emerging Platform for Multifunctional Hybrid Materials

“…Bockstaller and coworkers (Ojha et al 2013) have recently demonstrated that the enhanced control of the chemical composition of polymer grafts that is afforded by SI-ATRP facilitates the synthesis of thermoplastic polymer nanocomposite materials with high inorganic filling fraction. In particular, it was found that favorable interactions between grafted polymer and matrix polymer (here, poly(styrene-racrylonitrile)/poly(methyl methacrylate)) facilitate thermodynamically stable and uniform particle dispersion with inorganic filling fractions exceeding 50 % by volume (the term "polymer-filled inorganics" was introduced to highlight the majority content inorganic).…”

“…A particularly well-known example is the modification of gold (and other heavy metal) nanocrystals with thiol-functionalized polymers. Due to their experimental viability, grafting-to modification reactions have been among the most widely used polymer-modification techniques, for example, to achieve compatibilization of inorganic particles to organic embedding media (Ojha et al 2013). Major advantages of the grafting-to functionalization process involve the wide range of possible polymer chemistries as well as the ability to control chain architectures such as linear, comb, or star (as long as a proper end-functionality allows for tethering of the chain to the surface), as well as the scalability and possibility of continuous processing.…”

“…This relation of catalyst concentration and MW disparity offers new opportunities to synthesize polymers with designed dispersity that could exhibit favorable physicochemical properties for some applications. For example, disperse chain ligands have been proposed to enhance the miscibility of particle brushes in polymer embedding media (Ojha et al 2013). Note that if the contribution of radical termination is negligible, the catalyst concentration can be reduced even without reducing agents.…”

Synthesis of hydroxyapatite particles with in situ immobilized ATRP initiator

“…This approach assumes the same reactivity of both molecules; therefore simply by controlling their ratio in the reaction mixture one can control the concentration of active species on the modified surface [27,38,39]. Unfortunately, in a case of any difference in the reactivity of real and "dummy" initiators, different composition on the surface when compared to the modifying mixture will be generated [40].…”