Effect of Macrocycles on the Temperature-Responsiveness of Poly[(methoxy diethylene glycol methacrylate)-graft-PEG]
✍ Scribed by Hiromi Kitano; Tadashi Hirabayashi; Makoto Gemmei-Ide; Mayumi Kyogoku
- Publisher
- John Wiley and Sons
- Year
- 2004
- Tongue
- English
- Weight
- 175 KB
- Volume
- 205
- Category
- Article
- ISSN
- 1022-1352
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✦ Synopsis
Abstract
Summary: A homopolymer of 2‐(2′‐methoxyethoxy)ethyl methacrylate (DM) dissolved in pure water demonstrated an abrupt increase in its turbidity at a critical temperature (LCST). Meanwhile, the LCST for a copolymer of DM and ω‐methoxy(oligoethyleneoxy)ethyl methacrylate (P~a~M) (PDMP~a~M) significantly increased with increasing content of P~a~M residue. Furthermore, the addition of macrocycles such as hexasodium calix[6]arenehexasulfonic acid (SCX~6~), α‐cyclodextrin (α‐CD) and 2,6‐di‐O‐methyl‐β‐cyclodextrin (DM‐β‐CD) changed the LCST. SCX~6~ raised the LCST significantly, DM‐β‐CD slightly raised the LCST and α‐CD slightly lowered it. These phenomena could be attributed to the formation of an inclusion complex (polypseudorotaxane) at the grafted PEG chain of the copolymer. ROESY, fluorescence measurements and the viscosity behavior of the SCX~6~‐PEG dimethylether (PEG‐DME) mixture supported the theory of the complexation of SCX~6~ with the PEG chain. The apparent association constants (K~app~) of PEG‐DME or grafted PEG with SCX~6~ and α‐CD were determined using fluorescence and UV‐vis absorption measurements, respectively. The complexation of the SCX~6~‐polymer conjugate with PDMP~a~M was also examined by time‐evolution measurements of the turbidity. The effect of the structure of guest and host molecules on the LCST for the copolymer was discussed in detail.
Schematic representation of the formation of polypseudorotaxane of PDMP~a~M with SCX~6~.
magnified imageSchematic representation of the formation of polypseudorotaxane of PDMP~a~M with SCX~6~.