Synthesis and Stereocomplex Formation of Star-Shaped Stereoblock Polylactides Consisting of Poly(l-lactide) and Poly(d-lactide) Arms

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• 作者：Takuya Isono ; Yohei Kondo ; Issei Otsuka ; Yoshiharu Nishiyama ; Redouane Borsali ; Toyoji Kakuchi ; Toshifumi Satoh
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：November 12, 2013
• 年：2013
• 卷：46
• 期：21
• 页码：8509-8518
• 全文大小：550K
• 年卷期：v.46,no.21(November 12, 2013)
• ISSN：1520-5835

文摘

The synthesis of star-shaped polylactides (PLAs) having both poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) arms in one molecule, i.e., stereo-miktoarm star-shaped PLAs, is described. The azido-functionalized PDLAs and ethynyl-functionalized PLLA possessing linear and two- and three-branched structures were prepared by the ring-opening polymerization of d-lactide and l-lactide using azido- or ethynyl-functionalized initiators. The number-average molecular weights (M_n,NMRs) of the PLAs were ca. 5000 g mol^鈥? with narrow molecular weight distributions (M_w/M_ns) of less than 1.18. The click reaction of the azido-functionalized PDLAs and the ethynyl-functionalized PLLAs using the copper(I) bromide/N,N,N鈥?N鈥?N鈥?pentamethyldiethylenetriamine catalyst in a mixed solvent of dichloromethane/1,1,1,3,3,3-hexafluoro-2-propanol (14/1, v/v) gave a linear stereoblock PLA as well as 3-, 4-, 5-, and 6-armed stereo-miktoarm star-shaped PLAs with M_n,NMRs of ca. 10鈥?00 g mol^鈥? and M_w/M_ns of less than 1.16. The wide-angle X-ray scattering and differential scanning calorimetry measurements proved that these stereo-miktoarm star-shaped PLAs formed stereocomplex crystals without any trace of homochiral crystallization.