Glass transition of poly (methyl methacrylate) filled with nanosilica and core-shell structured silica. (3rd October 2017)

• Record Type: Journal Article
• Authors: Song, Yihu; Bu, Jing; Zuo, Min; Gao, Yang; Zhang, Wenjing; Zheng, Qiang
• Is Part Of: Polymer. Volume 127(2017)
• Page Start: 141
• Page End: 149
• Publication Date: 2017-10-03
• Subjects: Core-shell nanocomposite -- Poly (methyl methacrylate) -- Nanosilica -- Glass transition -- Segmental dynamics; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2017.08.038
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Core-shell (CS) nanocomposite particles with 53.4 wt% cross-linked poly (methyl methacrylate) (PMMA) shell of 11.6 nm in thickness were fabricated via miniemulsion polymerization of methyl methacrylate in the presence of modified nanosilica. The influence of nanosilica and CS nanoparticles on glass transition and segmental dynamics of PMMA in the nanocomposites prepared via solution casting was compared. The remarkable depression (≥10 °C) of glass transition temperature ( T g ) induced by the incorporation of SiO2 and CS was both observed at low loadings. Here, different mechanisms were responsible for the effect of SiO2 and CS on the segmental acceleration of PMMA matrix. The formation of rigid amorphous fraction (RAF) layer around SiO2 with the thickness of 16.4 nm led to the adjacent molecular packing frustration, while the "lubrication" effect of nonwetting interface between the grafted crosslinked chains and matrix chains resulted in the segmental acceleration and the reduction of dynamic fragility. Graphical abstract: The formation ofRAF layer around SiO2 leaded to the adjacent molecular packing frustration, while the "lubrication" effect of nonwetting interface around CS caused the segmental acceleration. Highlights: Core-shell (CS) nanoparticles with crosslinked PMMA shell were fabricated. The remarkable depression of T g induced by SiO2 and CS was both observed at low loadings. The formation of RAF layer around SiO2 leaded to the adjacent molecular packing frustration. The "lubrication" effect of nonwetting interface around CS caused the segmental acceleration.