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Effect of Macrocycles on the Temperature‐Responsiveness of Poly[(methoxy diethylene glycol methacrylate)‐ graft ‐PEG]
Author(s) -
Kitano Hiromi,
Hirabayashi Tadashi,
GemmeiIde Makoto,
Kyogoku Mayumi
Publication year - 2004
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200400135
Subject(s) - lower critical solution temperature , chemistry , polymer chemistry , methacrylate , copolymer , peg ratio , ethylene glycol , diethylene glycol , comonomer , cyclodextrin , polymer , organic chemistry , finance , economics
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 .