Synthesis and thermoresponsive properties of polymethacrylate molecular brushes with oligo(ethylene glycol)-block-oligo(propylene glycol) side chains

The synthesis and solution properties of thermoresponsive polymer molecular brushes based on five novel diblock macromonomers (methoxy [oligo(ethylene glycol)e-block-oligo(propylene glycol)p] methacrylates, OEGeOPGpMA, where e = 7.0–10.3 and p = 2.8–10.3) have been studied. The effect of synthesis conditions on the rate of radical solution polymerization in ethyl acetate, maximum conversions of macromonomers, and molecular weight characteristics of polymers has been shown. Homopolymers of OEGeOPGpMA exhibited pronounced surface-active properties. The influence of the length of oligo(propylene glycol) block on the degree of reduction of surface (air–water) and interfacial (hexane-water) tension was shown. The aggregation behavior of polymers was investigated by dynamic light scattering and fluorimetry using pyrene as a fluorescent probe. The dependence of critical micelle concentration on the length of the oligo(propylene glycol) block was shown. The polymers have a critical solution temperature within the range of 34–71 °C depending on the length of oligo(oxyalkylene) blocks and polymer concentration. The relationship between the distribution coefficient of macromonomers in water–oil systems and the LCST of polymers based on them has been established.