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Journal of the Korean Chemical Society (JKCS)

ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 42, Number 1
JKCSEZ 42(1)
February 20, 1998 
 
Title
 Formation of Complex Between Polyelectrolytes and pH/Temperature Sensitive Copolymers

고분자전해질과 pH/온도감응성 고분자 사이의 복합체 형성에 관한 연구
Author
 Mi Kyong Yoo, Yong Kiel Sung*

유미경, 성용길
Keywords
Abstract
 고분자 전해질 복합체 형성이 poly(N-isopropyl acrylamide)(PNIPAAm)공중합체의 저임계 용해온도 (lower critical solution temperature, LCST)에 미치는 영향을 조사하기 위하여 N-isopropyl acrylamide (NIPAAm) 와 acrylic acid (AAc) 를 선택하여 온도 감응성과 pH감응성을 동시에 지니는 pH/온도감응성 고분자를 합성하였다.합성된 고분자들을 FT-IR과 적정실험을 통해 확인하였다. 고분자전해질로서 poly(allylamine) (PAA)과 poly(L-lysine) (PLL)을 사용하여 pH2로부터 12에 이르는 넓은 범위의 pH영역에서 고분자 전해질 복합체 형성이 pH/온도감응성 고분자의 LCST에 미치는 영향을 조사하였다. 수용액상에서 poly(NIPAAm-co-AAc)중 PNIPAAm의LCST는 cloud-point 측정 방법으로 결정하였다. 또한 역정정 실험을 통해 공중합체 중의 AAc 함량을 결정하고 AAc의 이온화 정도가 LCST 에 미치는 영향을 조사하였다. 수용액상에서 poly(NIPAAm-co-AAc)중 PNIPAAm의LCST는 pH, 고분자전해질의 존재 유무, AAc의 함량, 그리고 고분자 사슬에 존재하는 전하밀도 등에 큰 영향을 받았다. 고분자전해질 복합체는 PAAc의 pKa와 PAA또는 PLL의 pKb 사이인 중성영역에서 형성되었으며 PNIPAAm의LCST에 미치는 PLL의 영향은 PAA에 비해 크게 나타났다. Random copolymers of N-isopropyl acrylamide (NIPAAm) and acrylic acid (AAc) which exhibit temperature- and pH-responsive behavior were synthesized by free-radical polymerization. The copolymers were characterized by means of FT-IR spectrometry and titration. The influence of polyelectrolyte on the lower critical solution temperature (LCST) of pH/temperature-sensitive polymers was investigated in the pH range of 2-12. The LCSTs of PNIPAAm/water in poly(NIPAAm-co-AAc) were determined by cloud-point measurements. A polyelectrolyte complex was prepared by mixing poly(NIPAAm-co-AAc) with poly(allylamine) (PAA) or poly(L-lysine) (PLL) solutions as anionic and cationic polyelectrolytes, respectively. Back titration was performed to determine the content of AAc and to study the effect of comonomer ionization on the LCST. The LCSTs of PNIPAAm/water in the copolymers were strongly affected by pH, presence of polyelectrolyte, AAc content, and charge density on the polymer. The polyelectrolyte hydrophobic PLL as polyelectrolyte on the cloud-point of PNIPAAm/water in the copolymer was stronger than that of poly(allylamine) (PAA).
Page
 84 - 91
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