A Nanoconfinement Effect Imposed by the Limited End-to-End Distance of the Grafted Chains on a Molecular Aggregation of Polymer Brushes with Crystalline Side Groups

作者：Zuo, Biao^*; Bai, Lu; Li, Zhiying; Xu, Hao; Li, Yun; Wang, Xinping^*

来源：Macromolecules, 2018, 51(22): 9192-9202.

DOI：10.1021/acs.macromol.8b02049

• COMB-LIKE POLYMERS
• X-RAY-DIFFRACTION
• THIN-FILM
• LAMELLAR ORIENTATION
• GLASS-TRANSITION
• CHARGE-TRANSPORT
• SURFACE
• DENSITY
• STATE
• WEIGHT

We demonstrated, using grazing incidence wide-angle X-ray diffraction (GI-WAXD), sum frequency generational spectroscopy (SFG), and atomic force microscopy (AFM), that the aggregation state and molecular ordering of polymer brushes with crystalline side groups (i.e., poly(n-octadecyl methacrylate)) can be well controlled by their grafting densities (sigma(p)). The long-range ordered structure, which is the lamellar structure formed by rodlike n-octadecyl (C18) side groups, sequentially changes with increasing grafting density from the standard lamellae with a periodicity (d(lam)) of 3.0 nm at low sigma(p), to shrinking lamellae with d(lam) = 2.6 nm, and then to a structure lacking lamellar ordering. This regulation is ascribed to the restricted conformation and suppressed lateral mobility of the densely grafted chains and most importantly to a particular spatial confinement imposed by the limited end-to-end distance of the tethered chains, which hinders the long-range ordered organization of the bulky side groups. Meanwhile, we also showed that such a confinement effect occurring in densely tethering chains can be mitigated by introducing a soft grafting substrate.

• 出版日期2018-11-27
• 单位浙江理工大学