Double Glass Transition Temperatures of Poly(methyl methacrylate) Confined in Alumina Nanotube Templates

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• 作者：Linling Li ; Dongshan Zhou ; Dinghai Huang ; Gi Xue
• 刊名：Macromolecules
• 出版年：2014
• 出版时间：January 14, 2014
• 年：2014
• 卷：47
• 期：1
• 页码：297-303
• 全文大小：470K
• ISSN：1520-5835

文摘

Recently, confinement of polymers with different geometries has become a research hotspot. Here, we report the dramatic deviation of glass transition behaviors of poly(methyl methacrylate) (PMMA) confined in cylindrical nanopores with diameter significantly larger than chain鈥檚 radius of gyration (R_g). Fast cooling a PMMA melt in the nanopores results in a glass with one single glass transition temperature (T_g). But two distinct T_gs are detected after slow cooling the melt. The deviation in T_g could be as large as 45 K. This phenomenon is interpreted by a two-layer model. During vitrification under slow cooling two distinct layers are formed: a strongly constrained interfacial layer showing an increased T_g as compared to that of the bulk polymer and a core with a decreased T_g. By thermal annealing experiments, we find that these two T_gs are inherently correlated. In addition, the deviation of T_g for PMMA confined in nanopores reveals a dependence on molecular weight.