title: Glass transitions of poly(methyl methacrylate) confined in nanopores: conversion of three- and two-layer models.
abstract: The glass transitions of poly(methyl methacrylate) (PMMA) oligomer confined in alumina nanopores with diameters much larger than the polymer chain dimension were investigated. Compared with the case of 80 nm nanopores, PMMA oligomer confined in 300 nm nanopores shows three glass transition temperatures (from from low to high, denoted as Tg,lo, Tg,inter, and Tg,hi). Such phenomenon can be interpreted by a three-layer model: there exists an interphase between the adsorbed layer and core volume called the interlayer, which has an intermediate Tg. The behavior of multi-Tg parameters is ascribed to the propagation of the interfacial interaction during vitrifaction process. Besides, because of the nonequilibrium effect in the adsorbed layer, the cooling rate plays an important role in the glass transitions: the fast cooling rate generates a single Tg; the intermediate cooling rate induces three Tg values, while the ultraslow cooling rate results in two Tg values. With decreasing the cooling rate, the thickness of interlayer would continually decrease, while those of the adsorbed layer and core volume gradually increase; meanwhile, the Tg,lo gradually increases, Tg,inter almost stays constant, and the Tg,hi value keeps decreasing. In such a process, the dynamic exchanges between the interlayer and adsorbed layer, core volume should be dominant.
authors: †Key Laboratory of High Performance Polymer Materials and Technology of Ministry of Education, Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China.
authors: Linling
authors: L
authors: Li
authors: †Key Laboratory of High Performance Polymer Materials and Technology of Ministry of Education, Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China.
authors: Jiao
authors: J
authors: Chen
authors: †Key Laboratory of High Performance Polymer Materials and Technology of Ministry of Education, Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China.
authors: Weijia
authors: W
authors: Deng
authors: †Key Laboratory of High Performance Polymer Materials and Technology of Ministry of Education, Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China.
authors: Chen
authors: C
authors: Zhang
authors: †Key Laboratory of High Performance Polymer Materials and Technology of Ministry of Education, Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China.
authors: Ye
authors: Y
authors: Sha
authors: †Key Laboratory of High Performance Polymer Materials and Technology of Ministry of Education, Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China.
authors: Zhen
authors: Z
authors: Cheng
authors: †Key Laboratory of High Performance Polymer Materials and Technology of Ministry of Education, Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China.
authors: Gi
authors: G
authors: Xue
authors: †Key Laboratory of High Performance Polymer Materials and Technology of Ministry of Education, Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, State Key Laboratory of Coordination Chemistry, Nanjing National Laboratory of Microstructures, Nanjing University, Nanjing 210093, P. R. China.|‡Xinjiang Laboratory of Phase Transitions and Microstructures in Condensed Matters, College of Physical Science and Technology, Yili Normal University, Yining 835000, P. R. China.
authors: Dongshan
authors: D
authors: Zhou