A study on the properties of PMMA/silica nanocomposites prepared via RAFT polymerization

Abstract

A number of batch polymerizations were performed to study the effect of pristine nanoparticle loading on the properties of PMMA/silica nanocomposites prepared via RAFT polymerization. In order to improve the dispersion of silica nanoparticles in PMMA matrix, the silanol groups of the silica are functionalized with methyl methacrylate groups and modified nanoparticles were used to synthesize PMMA/modified silica nanocomposites via RAFT polymerization. Prepared samples were characterized by thermogravimetric analysis (TGA), dynamic light scattering (DLS), dynamic mechanical thermal analysis (DMTA), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). According to results, introduction of modified nanoparticles results in better thermal and mechanical properties than those of pristine nanoparticles. Also, surface modification and increasing silica nanoparticles result in variation of thermal degradation behavior of nanocomposites. The best improvement of mechanical and thermophysical properties is achieved for nanocomposites containing 7 wt. % silica nanoparticles.

Nanofibers of poly (hydroxyethyl methacrylate)-grafted halloysite nanotubes and polycaprolactone by combination of RAFT polymerization and electrospinning

“…In physical methods, adsorption of polymer chains on a substrate is applied by physical bonds. However, in chemical methods, polymer chains are covalently attached to the surface via three common ways of Bgrafting from^, Bgrafting through^, and Bgrafting to^ [9][10][11][12][13][14][15][16][17]. Therein, grafting from is preferable to other methods because of its higher grafting density and thicker polymer layers.…”

Synthesis and characterization of diethyl-dithiocarbamic acid 2-[4-(2-diethylthiocarbamoylsulfanyl-2-phenyl-acetyl)-2,5-dioxo-piperazin-1-yl]-2-oxo-1-phenyl-ethyl ester as new reversible addition-fragmentation chain transfer agent for polymerization of ethyl methacrylate

“…Subsequently, [ 43,46] In RAFT polymerization mechanism (Scheme 2), rapid equilibrium between active propagating radicals (p ⋅ n and p ⋅ m in structure (g)) and the dormant polymeric thiocarbonylthio compound via chain transfer reactions avoids chains to be rapidly terminated. Therefore, thermally weak linkages such as head-to-head bond and chain-end unsaturation are been observed formerly in TGA analysis of poly(methacrylate) s prepared via traditional radical polymerization with different heating rates.…”

“…Therefore, thermally weak linkages such as head-to-head bond and chain-end unsaturation are been observed formerly in TGA analysis of poly(methacrylate) s prepared via traditional radical polymerization with different heating rates. [36,[42][43][44][45] Three stages of TRP-PEMA degradation include T d,max of 180, 290, and 385 °C related to thermal degradation of head-to-head linkages, unsaturated end groups, and random chain scission phenomena, respectively. Scheme 1. reaction route of the CTa synthesis.…”

In Situ Reversible Addition–Fragmentation Chain Transfer Polymerization of Styrene in the Presence of MCM‐41 Nanoparticles: Comparing “Grafting from” and “Grafting through” Approaches

“…Similar aggregated morphologies have also been observed in other polymer-grafted nanoparticles. [30][31][32] Hydroxyl groups on surface and in the pores of MCM-41 increase the tendency of particles to agglomerate in organic solvents. In the "grafting from" approach, in which the DDMAT agent was attached to the surface of MCM-41 particles, there is a probability of a bimolecular termination reaction of propagating radical of one particle with a propagating radical which is grafted to another particle.…”