title: Glass transition of poly(methyl methacrylate) nanospheres in aqueous dispersion.
abstract: Surfactant-free nanospheres and latex nanospheres of poly(methyl methacrylate) (PMMA) with diameter ranging from 20 to 220 nm are prepared by atom transfer radical polymerization (ATRP) in microemulsions and subsequent dialysis against deionized water. The glass transitions of these PMMA nanospheres are characterized using nano differential scanning calorimetry (nano-DSC) in aqueous dispersions. The glass transition temperature (Tg) of the surfactant-free PMMA nanospheres and nonionic PMMA latex nanospheres with diameters below 150 nm is less than that of the PMMA bulk, and Tg decreases with the decrease of the diameter. In contrast, Tg of the anionic PMMA latex nanospheres is size-independent and is near to that of the PMMA bulk. The influence of the environment surrounding the PMMA nanospheres on glass transitions as well as comparisons to our prior studies with polystyrene (PS) nanospheres in aqueous dispersions are discussed.
authors: Key Lab for Polymer Composite and Functional Materials of Ministry of Education, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou, 510275, China. ceszfm@mail.sysu.edu.cn.
authors: Shuo
authors: S
authors: Feng
authors: Yuenan
authors: Y
authors: Chen
authors: Biyun
authors: B
authors: Mai
authors: Wanchu
authors: W
authors: Wei
authors: Caixia
authors: C
authors: Zheng
authors: Qing
authors: Q
authors: Wu
authors: GuoDong
authors: G
authors: Liang
authors: HaiYang
authors: H
authors: Gao
authors: FangMing
authors: F
authors: Zhu