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Synthesis and Characterization of Isoindigo‐Based Polymers with Thermocleavable Side Chains
Author(s) -
Bini Kim,
Xu Xiaofeng,
Andersson Mats R.,
Wang Ergang
Publication year - 2018
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201700538
Subject(s) - side chain , polymer , thermal stability , polymer chemistry , solubility , copolymer , materials science , pendant group , chemical engineering , transmission electron microscopy , polymer solar cell , chemistry , organic chemistry , nanotechnology , composite material , engineering
Stability of bulk heterojunction films for organic solar cells is a critical factor for commercial viability. One method to stabilize these films is to include cleavable side chains, which reduce the solubility of the polymers when removed. In order to study the stabilizing effect of cleavable side chains, a series of random copolymers using isoindigo with 0, 10, 20, 50, and 100% thermally cleavable side chains based on the tert‐ butyloxycarbonyl ( t ‐BOC) group are synthesized. The polymers show a distinct one‐step thermal cleavage of the side chains, with no separable dealkylation and decarboxylation steps. The thermal stability in film is studied with transmission electron microscopy and atomic force microscopy. The polymer with all t ‐BOC side chains on isoindigo significantly improves thermal stability with regard to crystal growth and phase separation in film. These results suggest BOC‐substitution can be used for large scale processing to produce insoluble polymer films with a high degree of thermal stability.