2024-03-29T13:33:41Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/628962022-11-17T02:08:08Zhdl_2115_20045hdl_2115_139Hydrogel formation by the 'topological conversion' of cyclic PLA-PEO block copolymersYamamoto, TakuyaInoue, KotaroTezuka, Yasuyuki431An amphiphilic cyclic block copolymer consisting of poly(L- or D-lactide) and poly(ethylene oxide), that is, PLLA-PEO or PDLA-PEO, was synthesized from its corresponding linear triblock precursor, PLLA-PEO-PLLA or PDLA-PEO-PDLA, respectively, with alkenyl end groups. A mixture of the micellar dispersions of linear PLLA-PEO-PLLA and linear PDLA-PEO-PDLA formed a gel upon heating, whereas a mixture of the cyclic counterparts did not undergo this phase transition. These results suggest that the gelation behavior is directed by the topology of the polymer components. Furthermore, cyclic PLLA-PEO and cyclic PDLA-PEO block copolymers incorporating photocleavable o-nitrobenzyl units were synthesized. A mixture of the micellar dispersions of these block copolymers formed a gel upon ultraviolet irradiation via the 'topological conversion'.Nature Publishing GroupJournal Articleapplication/pdfhttp://hdl.handle.net/2115/62896https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/62896/1/4949_1_merged_1448367588-1-2.pdf0032-3896Polymer journal4843913982016-04enginfo:doi/10.1038/pj.2015.134author