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Associative pH Sensitive System
Author(s) -
Gosselet Noëlle Martine,
Wintgens Véronique,
Amiel Catherine
Publication year - 2005
Publication title -
macromolecular bioscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.924
H-Index - 105
eISSN - 1616-5195
pISSN - 1616-5187
DOI - 10.1002/mabi.200400197
Subject(s) - chemistry , polymer science
Summary: New associative pH sensitive systems composed of a modified dextran bearing 2‐carboxycyclohexyl carboxyl groups and neutral (p β CD) or positively charged (p β CDN + ) β ‐cyclodextrin‐ co ‐epichlorhydrin copolymers have been synthesized and their properties were investigated as a function of pH by phase diagrams and viscosimetry. The affinity between the CD cavities and the hydrophobic guests (2‐carboxycyclohexyl carboxyl groups) has been studied as a function of pH. The system with the neutral p β CD shows a pH dependant behavior due to the lowest affinity of the guest at pH above 5 for the cavity. Associative phase separation is produced at low pH whereas soluble complexes occur at higher pH. The opposite trend is observed with the system containing the cationic p β CDN + . This behavior is due to the combination of electrostatic and inclusion complex interactions in this system. Addition of salt, by screening the electrostatic interactions, also strongly influences the response of the system.Interaction of a p β CD‐DM mixture at pH 2.5 (left) and neutral pH (right).