Pendant Groups Fine-tuning Thermal Gelation of Poly(ε-caprolactone)-b-Poly(ethylene glycol)-b-Poly(ε-caprolactone) Aqueous Solution

Novel poly(epsilon-caprolactone)-b-poly(ethylene glycol)-b- poly(epsilon-caprolactone) (PCL-PEG-PCL) bearing pendant hydrophobic c-(carbamic acid benzyl ester) groups (PECB) and hydrophiphilic amino groups (PECN) were synthesized based on the functionalized comonomer c-(carbamic acid benzyl ester)-epsilon-caprolactone (CABCL). The thermal gelation behavior of the amphiphilic copolymer aqueous solutions was examined. The phase transition behavior could be finely tuned via the pendant groups, and an abnormal phenomenon occurred that the solgel transition temperature shifted to a higher temperature for PECB whereas a lower temperature for PECN. The micelles percolation was adopted to clarify the hydrogel mechanism, and the effect of the pendant groups on the micellization was fur-ther investigated in detail. The results demonstrated that the introduction of c-(carbamic acid benzyl ester) pendant groups significantly decreased the crystallinity of the copolymer micelles whereas amino pendant groups made the micelles easy to aggregate. Thus, the thermal gelation of PEG/PCL aqueous solution could be finely tuned by the pendant groups, and the pendant groups modified PEG/PCL hydrogels are expected to have great potential biomedical application. (C) 2016 Wiley Periodicals, Inc.