Effects of surface modification and thermal annealing on the interfacial dynamics in core–shell nanocomposites based on silica and adsorbed PDMS

Interfacial dynamics of polydimethylsiloxane adsorbed on fumed metal oxide particles of a wide range of specific surface area

“…We have recently showed [19] that surface modification of low specific surface area fumed silica (58 m 2 /g) with small zirconia nanoparticles resulted in slightly increased S and in faster and more cooperative interfacial relaxation, these effects suggesting an increase of PDMSeparticle contact points, in qualitative agreement with effects obtained here with S and a int of the NCs. Finally, the adequacy of the model proposed above was examined, additionally, in our recent work [27] in similar systems of silica/PDMS by means of (a) surface modification of silica of initially high S (342 m 2 /g) with zirconia nanoparticles resulting in strongly suppressed S and (b) thermal (crystallization) annealing, the results for interfacial polymer being in qualitative agreement with those obtained in the present study. A term often employed for the description of the range [2,10] of polymerefiller interactions is the distance from the particles' surface, up to which the characteristics of interfacial (modified) polymer dominate, in other words, the thickness of the interfacial layer [15].…”

Direct Relationship Between Interfacial Microstructure and Confined Crystallization in Poly(Ethylene Oxide)/Silica Composites: The Study of Polymer Molecular Weight Effects

“…Similar conflicting results to those reported above for the interphase in PNCs can also be found for thin polymer films . It has been reported that such controversies are not only related to compositional variations but also dependent on the method of preparation and the experimental technique employed . Therefore, a systematic characterization of polymer–nanoparticle interactions is of great theoretical importance, as it can provide a way to control the interfacial polymeric structure with the goal of optimizing the desirable properties of PNCs.…”

“…There has been considerable interest in characterizing polymer chains within the interphases, since it underpins the advantageous physical, thermal, and mechanical properties of polymer nanocomposites (PNCs) . Despite many reports on the interfacial polymer, a comprehensive model that describes the quantitative relationship between the microstructure of the interphase and the macroscopic properties of nanocomposites is still lacking. Such a model could be essential to the design and application of nanocomposites.…”

DSC study of silicas with immobilized polysiloxane layer of different architecture

“…According to the authors [24], long molecules form loops-like structures with contacts on each curl of the polymer spiral. According to another report [19], the immobilized molecules form linear tails directed from the silica surface at the initial stage of adsorption (chemisorption), which bend into a helix with a further increase in the concentration of the adsorbate. Both theories suggest a monolayer forming of new adsorption sites at some distance from the surface, which reduces the conformational stresses on the next step of modification.…”

“…At the same time, bulk dynamics (glass transition temperature-T g , and time scale of a relaxation) were not significantly affected. This effect has been widely studied [16][17][18][19], and authors proposed a model of bimodal conformations of polymers adsorbed on solid surfaces, in terms of an increase in the apparent thickness of the interfacial layer with increasing surface roughness. According to this model, the conformations of polymer chains during the first stage of adsorption are mostly linear (tails) with following formation of loop-like structures with polymer content increase.…”