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URN etd-0612116-154404
Author PEI-YI LIN
Author's Email Address No Public.
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Department Materials and Optoelectronic Science
Year 2015
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title CO2 responsiveness of Poly(N-isopropylacrylamide-co-methacrylic acid)
Date of Defense 2016-06-16
Page Count 113
Keyword
  • N-isopropylacrylamide
  • acrylic acid
  • methacrylic acid
  • lower critical solution temperature
  • supercritical CO2
  • responsive polymers
  • Abstract In this study, random copolymers of poly(N-isopropylacrylamide-co-acrylic acid) (i.e., poly(NIPAAm-co-AA)) and poly(N-isopropylacrylamide-co-methacrylic acid) (i.e., poly(NIPAAm-co-MAA)) were prepared by free radical polymerizations and block copolymer of poly(methacrylic acid-b-N-isopropylacrylamide) (i.e., PMAA-b-PNIPAAm)) was prepared by reversible-addition-fragmentation chain transfer radical polymerization. Temperature, pH, and CO2 responsiveness of these copolymers were investigated. UV-vis, DSC, and digital camera were used to investigate the pH dependence of the lower critical solution temperature (LCST) for copolymer aqueous solutions. Experimental results found that LCST of all aqueous solutions were increasing with increasing pH. High pressure DSC measurements found that LCST of poly(NIPAAm-co-AA) was decreasing with increasing CO2 pressure. Tg of films as cast from aqueous solutions of as-synthesized random copolymers were increasing with increasing AA (or MAA) compositions in NIPAAm-rich copolymers but decreasing with AA (or MAA) compositions in AA (or MAA)-rich copolymers. This suggested that strong hydrogen bondings be formed between amide groups of NIPAAm units and carboxylic acid groups of AA (or MAA) units. Tg of random copolymers films as cast from aqueous solutions of different pH was seen to first decrease with pH and then increase with pH. This indicated that COOH dissociated to COO- as pH was increased, leading to a decrease of Tg because of a decrease of intermolecular hydrogen bonding, and COOH could completely dissociate to COO- as pH was increased to be high, leading to an increase of Tg with pH because the negatively charged copolymer molecules could become rigid. Following treatments in a supercritical carbon dioxide fluid (scCO2), Tg of random copolymer film was increased due to promotion of intermolecular hydrogen bonding by scCO2; however, Tg of block copolymer film was decreased due to the plasticizing effect of CO2 in the micelle of the block copolymer. Upon CO2 bubbling in aqueous solution of PMAA-b-PNIPAAm, CO2 responsiveness could be clearly seen by the change of the cloud point in aqueous solution at some particular conditions. CO2 responsiveness of poly(NIPAAm-co-AA) and poly(NIPAAm-co-MAA), however, were not clear.
    Advisory Committee
  • Jin-Long Hong - chair
  • Yeo-Wan Chiang - co-chair
  • Yeong-Tarng Shieh - co-chair
  • Shiao-Wei Kuo - advisor
  • Files
  • etd-0612116-154404.pdf
  • Indicate in-campus at 3 year and off-campus access at 3 year.
    Date of Submission 2016-07-12

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