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Paper
Soft Matter, 2009, 5, 2648 - 2657, DOI: 10.1039/b900539k
Smart hydrogels based on double responsive triblock terpolymers
Stefan Reinicke, Joachim Schmelz, Alain Lapp, Matthias Karg, Thomas Hellweg and Holger Schmalz
In this work a new kind of
smart
hydrogel is presented, which is composed of a poly(2-vinylpyridine)-block-poly(ethylene oxide)-block-poly(glycidyl methyl ether-co-ethyl glycidyl ether) (P2VP-b-PEO-b-P(GME-co-EGE)) triblock terpolymer. The thermo-sensitive poly(glycidyl methyl ether-co-ethyl glycidyl ether) block exhibits a cloud point which is easily adjustable by the comonomer ratio. Copolymerization of GME and EGE produces nearly statistical copolymers with a weak preferential incorporation of GME, exhibiting a sharp coil-to-globule transition with almost no hysteresis. The triblock terpolymers aggregate in aqueous solution triggered by both pH and temperature. At sufficiently high concentration this stimuli-responsive behaviour leads to a reversible gel formation with gel strengths and transition points tuneable by pH, temperature, concentration, and block lengths. At pH = 7, an unique gel–sol–gel transition accompanied with a strengthening of the gel is observed upon heating using rheology. Moreover, the structure of the low temperature gel phase is investigated by means of small-angle neutron scattering (SANS).
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