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New pH sensitive network: Combination of an amphiphilic degradable polyester with a β‐cyclodextrin copolymer
Author(s) -
Moine Laurence,
Cammas Sandrine,
Amiel Catherine,
Renard Estelle,
Sébille Bernard,
Guérin Philippe
Publication year - 1998
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.19981300105
Subject(s) - copolyester , copolymer , polymer chemistry , epichlorohydrin , monomer , cyclodextrin , amphiphile , polyelectrolyte , polymerization , chemistry , polyester , aqueous solution , polymer , materials science , organic chemistry
A novel hydrophobic monomer, ethyladamantyl malolactonate, has been synthesized and copolymerized with benzyl malolactonate by anionic ring‐opening polymerization. The ratio of adamantyl monomer varied from 0 to 100 mol%. Deprotection of benzyl groups leads to a water soluble copolyester with carboxylic acid lateral functions which give a polyelectrolyte character to the corresponding polymers. The mixture of a copolyester containing 10% of adamantyl groups and a β‐cyclodextrin/epichlorohydrin copolymer in aqueous solution leads to a new pH‐dependant associating system. The solution behavior of this system was studied by viscosimetry as a function of pH, concentration and ratio of both copolymers. At the initial solution pH (pH=2), the copolyester adopts a coiled structure as a result of hydrophobic interactions between the pendant adamantyl groups. Consequently, no network formation is observed as shown by a very low viscosity. As the pH increase, the viscosity of the medium increases and reaches a maximum at pH=5. At this pH, the copolyester expands because of electrostatic repulsions between the carboxylate pendant functions. Consequently, the adamantyl groups are accessible and can be encapsulated into the β‐cyclodextrin cavities resulting in a significant increase of the viscosity.