Effects of molecular mass and surface treatment on adsorbed poly(methyl methacrylate) on silica

Abstract

The behavior of relatively monodisperse adsorbed poly(methyl methacrylate) (PMMA) samples, from 19 to 587 kDa on silica, was studied using modulated differential scanning calorimetry and FTIR. On untreated CabOSil silica, the glass transition temperatures (Tgs) were higher (by around 30 °C), and the transitions were significantly broader (by a factor of 5–6) than those for the corresponding bulk samples. While the Tgs for the bulk polymers showed the expected dependence on molecular mass, the polymers on untreated silica showed little dependence, i.e., at the same adsorbed amounts, the glass transitions were very similar. The FTIR spectra of the adsorbed PMMA (on untreated silica) showed the presence of at least two resonances, one for the bound (hydrogen bonded to surface silanols) and another for free carbonyls. Fitting of the spectra allowed the estimation of the bound fractions of carbonyls that were dependent on the adsorbed amount, but not molecular mass. On CabOSil treated with hexamethyldisilizane (HMDS), the adsorbed PMMA exhibited glass transition behavior with little molecular‐mass dependence; the Tgs for the different PMMA samples were very similar to those of the high‐molecular mass bulk polymer, but with additional broadening of about a factor of 2. FTIR spectra for the PMMA samples on the treated silica did not show significant amounts of any of the hydrogen‐bonded carbonyl groups. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 649–658, 2008

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

“…33 In this spectral region, no absorption bands are detectable for MMA-SiO 2 thus indicating that the monomer is not interacting with the silica surface. In the case of PMMA 5 -SiO 2 and PMMA 7 -SiO 2 , the spectra present a complex broad band 35,36 centred at around 1720 cm À1 while for PMMA 16 -SiO 2 it is clearly observable that this broad band is constituted by two partially convoluted peaks centered at around 1730 cm À1 and 1714 cm À1 , respectively. To estimate the interacting fraction, the carbonyl bands of all samples were resolved in two components using a mixed Gauss-Lorentz function, as illustrated in the onset of Fig.…”

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

“…Previous studies on small amounts of poly(methyl methacrylate) (PMMA) adsorbed on silica reported that the PMMA glass transition temperature ( T g ) broadened and shifted to a higher temperature than the bulk polymer . This exact behavior depended on the adsorbed amounts and also surface treatments . The small amounts of adsorbed polymers require the use of very large surface‐area substrates, but the consequent sensitivity problems hamper these studies.…”

Disruptions in the crystallinity of poly(lauryl methacrylate) due to adsorption on silica

“…Studies have demonstrated that when acrylate or methacrylate polymers are adsorbed on silica, interactions between the carbonyl groups on the polymer and the silanol groups on the silica result in the decreased mobility and increased T g of the polymer . Hydrogen bonding was observed in Figure from the shift in the carbonyl resonance frequency as well as the disappearance of the isolated silanol peak.…”