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Stereocomplex‐ and Homo‐Crystallization and Phase‐Transition Behavior of Relatively High‐Molecular‐Weight Linear One‐ and Two‐Armed and Star‐Shaped Four‐Armed Poly(l‐lactide)/Poly(d‐lactide) Blends
Abstract:Relatively high‐molecular‐weight linear one‐ and two‐armed and star‐shaped four‐armed poly(l ‐lactide) and poly(d ‐lactide) are synthesized and the multiplicate effects of arm‐number (branching architecture, coinitiator moiety), crystallization temperature (T c), and number‐average molecular weight (M n) on stereocomplex (SC)‐ and homo‐crystallization and phase‐transition behavior are investigated. For nonisothermal and isothermal crystallization, in addition to SC crystallites, homo‐crystallites are formed in the blends with higher M n values, irrespective of arm number. For isothermal crystallization, the transition T c ranges below which in addition to SC crystallites, homo‐crystallites are formed depended on M n per one arm‐determining melting temperature or thickness of homo‐crystallites. The transition M n ranges above which in addition to SC crystallites, homo‐crystallites are formed are not affected by arm number. The high molecular weight disturbs the change of crystalline growth mechanism of one‐ and two‐armed blends, whereas the branching architecture inhibits the change of crystalline growth mechanism of four‐armed blends.
Keywords:branched polymer  phase transition  poly(lactic acid)  stereocomplex crystallization  stereo‐specific polymers
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