Effect of Particle Structure and Surface Chemistry on PMMA Adsorption to Silica Nanoparticles

Abstract

The interphase layer of polymers adsorbed to silica surfaces can be affected by the surface silanol density as well as the relative size of the polymer compared with the size of the adsorbing substrate. Here, the nonequilibrium adsorption of PMMA onto individual colloidal Stober silica (SiO(2)) particles, where R(particle) (100 nm) > R(PMMA) (approximately 6.5 nm) was compared with the adsorption onto fumed silica, where R(particle) (7 nm) approximately R(PMMA) (6.5 nm) < R(aggregate) (approximately 1000 nm), as a function of both silanol density [SiOH] and hydrophobility. In the former case, TEM images showed that the PMMA adsorbed onto individual nanoparticles, so that the number of PMMA chains/bead could be calculated, whereas in the latter case bridging of PMMA between aggregates occurred. The anchoring point densities were comparable to the silanol densities, suggesting that PMMA adsorbed as trains rather than loops. For hydrophilic SiO(2), T(g) increased with [SiOH], as more carbonyl groups hydrogen bonded to the silanols, and was independent of particle morphology. For methylated silica, (CH(3))(3)SiO(2), the adsorption isotherms were identical for colloidal and fumed silica, but T(g) was depressed for the former, and comparable to the bulk value for the latter. The increased T(g) of PMMA adsorbed onto fumed (CH(3))(3)SiO(2) was attributed to the larger loops formed by the bridging PMMA chains between the silica aggregates.

Thermal Properties of PMMA on Silica Using Temperature‐Modulated Differential Scanning Calorimetry

“…This elevated transition for tightlybound polymer was reported in studies for polymers adsorbed on surfaces, but only when there was a strong interaction between the polymer and substrate. [28,30,34,35] Such an attraction can come from a specific interaction, such as hydrogen bonding between the polymer and a solid surface and this interaction exists in the PMMA/silica system. Tightly-bound polymer does not, for example, occur with weak interactions such as those as in polystyrene/silica.…”

The influence of oxide nanoparticles on the kinetics of free radical methyl methacrylate polymerization in bulk

“…The chain mobility close to the surface is influenced by the monomer segments which can be rearranged independently from their surrounding . Although, it is expected that the decreased mobility should increase the glass transition temperature ( T g ) , the opposite effect is noticed for syndiotactic and atactic poly(methyl methacrylate) . According to our literature review, there is still no data about the influence of the different oxide nanofiller nature (hydrophility or hydrophobity) on the kinetics of MMA radical polymerization, and on the formation of polymeric interfacial layer around nanofiller surface.…”

Rational design of nanoparticle/monomer interfaces: a combined computational and experimental study of in situ polymerization of silica based nanocomposites

“…Figure 2 presents FTIR spectra in the carbonyl region of PMMA n -SiO 2 . As known, hydrogen bounded carbonyls give rise to an absorption band at lower wavenumber than non-interacting carbonyl groups, free carbonyls, thus allowing to determine interactions between PMMA n and silica 33 . To verify the simulations findings, the occurrence of interactions between PMMA oligomers and SiO 2 surface was proved through Please do not adjust margins Please do not adjust margins absorption experiments.…”