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Nanowire Shish‐Kebab Structures and Molecular Orientation Control of All‐Conjugated Diblock Copolymers
Author(s) -
Yang Hua,
Wang Lei,
Yu Xinhong,
Zhang Jidong,
Geng Yanhou,
Han Yanchun
Publication year - 2014
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201301610
Subject(s) - copolymer , moiety , nanowire , materials science , conjugated system , stacking , crystallization , crystallography , polymer chemistry , annealing (glass) , polymer , chemical engineering , nanotechnology , stereochemistry , chemistry , organic chemistry , composite material , engineering
Herein we propose a facile strategy to prepare nanowires and nanowire “shish‐kebab” (NWSK) structures by controlling the crystallization behavior of all‐conjugated rod–rod diblock copolymers poly[( p ‐phenylene)‐ block ‐(3‐hexylthiophene)]s (PPP‐ b ‐P3HT (B m T n )) with varying main chain lengths. Depending on the block length and ratio (i.e., PPP/P3HT, abbreviated as B/T), nanowires with low B/T ratios (copolymers with long P3HT blocks; B8T32 and B14T34) and NWSKs with high B/T ratios (copolymers with long PPP blocks; B29T9 and B39T18) were formed for PPP‐ b ‐P3HT all‐conjugated diblock copolymers. The formation of nanowires is governed by a strong interchain π–π stacking similar to the P3HT homopolymer, with an edge‐on orientation of the P3HT moiety, whereas NWSKs are formed as a result of the particular face‐on molecular orientation of PPP moiety. As the length of the P3HT moiety was increased (the block ratio of PPP/P3HT reduced), the NWSKs were transformed into nanowires gradually because of the decreasing density of “kebabs”. For diblock copolymers with high PPP/P3HT ratios, the transition of the molecular orientation from face‐on to edge‐on was obtained by thermal annealing.