title: Scaled down glass transition temperature in confined polymer nanofibers.
abstract: Arrays of polymer nanostructures have been widely used in many novel devices and nanofabrication methods. The glass transition temperature, which is a key parameter influencing the long-term stability of polymer nanostructures, has not yet been systematically studied and well understood. Here we study this technological and fundamental issue with polymers of different values of molar mass M confined in nanocylinders of a varying diameter D. The glass transition temperature Tg loses its dependence on the molar mass for D ≲ 100 nm, a range in which the relative depression of Tg varies as D(-0.44). For higher cylinder diameters, Tg progressively recovers its dependence on the molar mass. This is quantitatively reproduced by a model based on an equilibrium interfacial excess of free volume, which needs to be created unless provided by the chain ends. Our findings suggest that the structural perturbations during nanofabrication may strongly affect the long-term stability of arrays of polymer nanostructures.
authors.affiliation: College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, China and College of Chemistry, Chemical Engineering and Materials, Soochow University, Suzhou 215123, China. zhijun.hu@suda.edu.cn.
authors.forename: Hongxia
authors.initials: H
authors.lastname: Wang
authors.affiliation: College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, China and Center for Soft Condensed Matter Physics and Interdisciplinary Research & Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006, China.
authors.forename: Tongxin
authors.initials: T
authors.lastname: Chang
authors.affiliation: College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, China and Center for Soft Condensed Matter Physics and Interdisciplinary Research & Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006, China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Li
authors.affiliation: College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, China and Center for Soft Condensed Matter Physics and Interdisciplinary Research & Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006, China.
authors.forename: Weidong
authors.initials: W
authors.lastname: Zhang
authors.affiliation: College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006, China and College of Chemistry, Chemical Engineering and Materials, Soochow University, Suzhou 215123, China. zhijun.hu@suda.edu.cn and Center for Soft Condensed Matter Physics and Interdisciplinary Research & Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006, China.
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Hu
authors.affiliation: Bio & Soft Matter, Institute of Condensed Matter and Nanosciences, Université catholique de Louvain, Croix du Sud 1/L7.04.02, B1348 Louvain-la-Neuve, Belgium. alain.jonas@uclouvain.be.
authors.forename: Alain M
authors.initials: AM
authors.lastname: Jonas