As a kind of smart material, thermoresponsive hydrogels are widely investigated and applied in many fields. Due to the limitation of the freezing temperature of the water, it is a challenge to further broaden their sol-gel transition temperature (Tgel ) range, especially below 0 °C. Herein, the lower critical solution temperature type of amphiphilic ABA triblock copolymers, synthesized via two-step reversible addition-fragmentation chain transfer (RAFT) polymerization is demonstrated. The hydrophilic A-block and the hydrophobic B-block are composed of poly(N,N-dimethylacrylamide) (PDMAA) and poly(diacetone acrylamide) (PDAAM), respectively. The degree of polymerization (DP) of both A-block and B-block shows a significant influence on the Tgel of triblock copolymer dispersion. By changing the length of these two blocks or physically blending these copolymers dispersions, the Tgel can be well adjusted in a temperature range from 45 to -10 °C. Moreover, When the Tgel is higher than 4 °C, the triblock copolymer coatings show a good anti-fogging property. And when the Tgel is around or lower than the freezing temperature of the water, aqueous dispersions of the triblock copolymer have an ice recrystallization inhibition activity, resulting in the decrease of average maximum grain size (MLGS) of ice crystal.
Keywords: amphiphilic triblock polymers; lower critical solution temperature type phase transition; reversible addition-fragmentation chain transfer polymerization; thermoresponsive hydrogels.
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