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Exclusive Synthesis of Poly(3‐hexylthiophene) with an Ethynyl Group at Only One End for Effective Block Copolymerization
Author(s) -
Zhang Geng,
Ohta Yoshihiro,
Yokozawa Tsutomu
Publication year - 2018
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201700586
Subject(s) - copolymer , block (permutation group theory) , end group , group (periodic table) , polymer chemistry , materials science , polymer science , chemistry , polymer , combinatorics , mathematics , organic chemistry , composite material
Well‐controlled synthesis of ethynyl‐functionalized poly(3‐hexylthiophene) (P3HT) is crucial for preparation of block copolymers containing the P3HT segment by means of click coupling reaction. A well‐known chain end modification method, in which Kumada–Tamao catalyst‐transfer polymerization is quenched with ethynylmagnesium chloride, under various conditions is re‐examined, but in all cases not only P3HT with an ethynyl group at one end but also P3HT di‐ethynylated at both ends is obtained. Accordingly, Sonogashira coupling reaction of P3HT having H/Br ends with trimethylsilylacetylene is tried, followed by removal of the trimethylsilyl group, and it is found that this protocol affords exclusively P3HT with an ethynyl group at one end. This post end‐modification method is applied to the synthesis of an amphiphilic diblock copolymer of P3HT and poly(2‐ethyl‐2‐oxazoline) (PEtOx) by means of click reaction between ethynylated P3HT and PEtOx with an azide group at one end, and the product is confirmed to be free from contamination with triblock copolymer. Micellization of this block copolymer is confirmed in tetrahydrofuran (THF)/water and THF/methanol mixtures.