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pH‐/temperature‐sensitive supramolecular micelles based on cyclodextrin polyrotaxane
Author(s) -
Huang Jin,
Ren Lixia,
Chen Yongming
Publication year - 2008
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.2396
Subject(s) - supramolecular chemistry , micelle , copolymer , acrylic acid , materials science , polymer chemistry , aqueous solution , chemical engineering , hydrogen bond , solvent , ethylene glycol , chemistry , polymer , organic chemistry , molecule , composite material , engineering
BACKGROUND: Based on the assembly strategy induced by host‐guest recognition in weak selective solvent, a kind of supramolecular nano‐micelles has been self‐organized from a water‐soluble diblock copolymer, poly(ethylene oxide)‐block‐poly(acrylic acid) (PEO‐b‐PAA), selectively included by ‐cyclodextrins (‐CDs). RESULTS: The spontaneous aggregation of rod‐like ‐CD/PEO‐based pseudo‐polyrotaxanes (pseudo‐PRs) drove the formation of square‐piece in aqueous media and thereafter evolved to spherical assemblies with or without hollow structure as time prolonged, which were stabilized by uncovered hydrophilic PAA segments. Such morphological evolvement attributed to hydrogen bonding between ··CCOOH in PAA and ··COH in ‐CD. However, when alkaline media was used to inhibit hydrogen bonding by ionizing ··CCOOH, the assemblies were only uniform spheres of ca. 100 nm. Meanwhile, the order stacking of PR rods became the basic building units all the time. Herein, the supramolecular PRs contributed to temperature‐response character, namely the formation of assemblies is reversible stimulated with temperature changes. Additionally, the inhibition of deceasing pH to the ionization of free PAA segments made assemblies fuse as microspheres. CONCLUSION: Such pH‐ and temperature‐sensitivity as well as the biocompatibility of components and water as media make a great potential of such nano‐particles as the biomedical materials with controlled‐release function. Copyright © 2007 Society of Chemical Industry