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Polyimide‐polyurethane/urea block copolymers for highly sensitive humidity sensor with low hysteresis
Author(s) -
Bae YuMi,
Lee YoungHee,
Kim HanSeong,
Lee DongJin,
Kim Sung Yeol,
Kim HanDo
Publication year - 2017
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.44973
Subject(s) - copolymer , materials science , polyimide , polymer chemistry , polyurethane , thermal stability , absorption of water , polymerization , condensation polymer , chemical engineering , composite material , polymer , layer (electronics) , engineering
Polyimide (PI)‐polyurethane‐urea (PU) block copolymers (PI‐PU75/25, PI‐PU50/50, and PI‐PU25/75) were prepared by reaction between anhydride‐terminated poly(amic acid) prepolymers with various number‐average degree of polymerization (X n ¯ = 73/49/25) and isocyanate‐terminated urethane‐urea prepolymers with variousX n ¯(11/21/31) to obtain high performance capacitive humidity sensors. Pure PI and PU were also prepared to compare with PI‐PU copolymers. This study examined the effect of PU content on the water absorption %/water vapor transmission rate, thermal and mechanical properties and sensing properties of PI‐PU block copolymers. The thermal stability and mechanical properties of the copolymer decreased markedly with increasing PU content. The sensitivity of sensor increased sharply with increasing PU content from 0 to 25 wt %, and then increased a little. The hysteresis of sensor decreased sharply with increasing PU content up to 50 wt %, and then decreased a little. These results demonstrate the apparent upside of using two copolymers (PI‐PU75/25 and PI‐PU50/50) compared to using pure PI, in terms of sensor performance. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44973.