Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (04): 1157-1163.doi: 10.3866/PKU.WHXB20100431

• PHYSICAL CHEMISTRY OF MATERIALS • Previous Articles     Next Articles

Effect ofMolecular Structure on the Surface Morphology of Ultrathin Films by Competing Crystallization and Dewetting Processes

YUAN Wei-Zhong, ZHANG Feng-Bo, YUAN Jin-Ying, XIE Xu-Ming, HONG Xiao-Yin   

  1. Key Laboratory of Organic Optoelectronics&Molecular Engineering of the Ministry of Education, Department of Chemistry, Tsinghua University, Beijing 100084, P. R. China; Institute of Nano and Bio-Polymeric Materials, School of Material Science and Engineering, Tongji University, Shanghai 200092, P. R. China; Department of Chemical Engineering, Tsinghua University, Beijing 100084, P. R. China
  • Received:2009-12-08 Revised:2010-02-05 Published:2010-04-02
  • Contact: YUAN Jin-Ying E-mail:yuanjy@mail.tsinghua.edu.cn

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Abstract:

Star-branched poly(ε-caprolactone) (PCL) including hexa-armed star-shaped PCL (HPCL), dendritic PCL (DPCL), and linear PCL (LPCL) were spin-coated onto mica substrates at room temperature. The effect of molecular structure on the wetting-dewetting behavior of ultrathin film(about 15 nm)was investigated with atomic force microscopy (AFM). During spin-coating, film formation is governed by competing dewetting and crystallization processes. According to differential scanning calorimetry (DSC), the crystallizability of DPCL is weaker than that of HPCL which is weaker than that of LPCL, when they have the same relative molecular mass. Depending on the molecular structure and the relative molecular mass of PCL, the competition between crystallization and dewetting results in ultrathin films of LPCL, HPCL, and DPCL with surface morphologies such as perfect spherulites, open spherulites, dendritic lamellae, and dispersed droplets of different sizes.

Key words: Wetting, Molecular structure, Dewetting, Crystallization, Ultrathin film