Premium
Thermo‐Responsive Organic/Inorganic Hybrid Hydrogels based on Poly( N ‐vinylcaprolactam)
Author(s) -
Loos Wouter,
Verbrugghe Sam,
Goethals Eric J.,
Du Prez Filip E.,
Bakeeva Irena V.,
Zubov Vitali P.
Publication year - 2003
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.200290058
Subject(s) - self healing hydrogels , silanol , materials science , chemical engineering , swelling , hybrid material , phase (matter) , aqueous solution , lower critical solution temperature , polymer chemistry , nanotechnology , polymer , chemistry , composite material , organic chemistry , catalysis , copolymer , engineering
A new type of ‘intelligent’ hydrogels has been developed in the form of organic/inorganic hybrid materials by making use of the sol‐gel technology. Poly( N ‐vinylcaprolactam) (PVCL) has been incorporated in these materials for its thermo‐responsive properties. The synthesis of the hybrid hydrogels was achieved by the in situ formation of an inorganic silica phase in the presence of an aqueous solution of high molecular weight PVCL. This methodology results in the preparation of micro‐heterogeneous systems in which silica particles of nanometer dimensions act as physical cross‐links for the PVCL molecules. Hydrogen bonds between the remaining non‐condensed silanol groups and the PVCL carbonyl functions, together with physical entanglements, are responsible for the strong interactions between the organic and inorganic phases. Stress‐strain tests on highly swollen materials demonstrated that the unique structure of these thermo‐responsive hybrid hydrogels improves the mechanical stability to a great extent as compared to conventional hydrogels. Transmission measurements demonstrate that the presence of the inorganic phase does not influence the cloud point temperatures of PVCL significantly. On the other hand, the response of the reinforced hybrid hydrogels to temperature becomes less pronounced for increasing silica fractions. The reversibility of the swelling/deswelling process has been demonstrated by swelling experiments as a function of temperature.PVCL/SiO 2 hybrid hydrogels.