Feng Shuo, Chen Yuenan, Mai Biyun, Wei Wanchu, Zheng Caixia, Wu Qing, Liang GuoDong, Gao HaiYang, Zhu FangMing
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.
Phys Chem Chem Phys. 2014 Aug 14;16(30):15941-7. doi: 10.1039/c4cp01849d.
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.
通过微乳液中的原子转移自由基聚合（ATRP）以及随后用去离子水进行透析，制备了直径范围为20至220纳米的聚甲基丙烯酸甲酯（PMMA）无表面活性剂纳米球和乳胶纳米球。使用纳米差示扫描量热法（nano-DSC）在水性分散体中对这些PMMA纳米球的玻璃化转变进行表征。直径低于150纳米的无表面活性剂PMMA纳米球和非离子PMMA乳胶纳米球的玻璃化转变温度（Tg）低于PMMA本体的玻璃化转变温度，并且Tg随着直径的减小而降低。相比之下，阴离子PMMA乳胶纳米球的Tg与尺寸无关，并且接近PMMA本体的Tg。讨论了PMMA纳米球周围环境对玻璃化转变的影响以及与我们之前在水性分散体中对聚苯乙烯（PS）纳米球的研究的比较。
