New material design of multi-stereo block poly(lactic acid)s by controlling the block length and the total molecular weight

ブロック長と分子量を制御したマルチステレオブロックポリ乳酸の合成とその物性

2017-09-25

2017-09-25

In this study, multi-stereo block poly(lactic acid)s (multi-sb-PLAs) with molecular weights of approximately 60,000 and 130,000 with various block lengths were synthesized from di-block copolymers consisting of L- and D-blocks with the same length are connected with 1,12-dodecanediol (DMG), an initiator and hexamethylene diisocyanate (HMDI), a chain extender alternately. The effects of the block length and the molecular weight on the thermal properties, the isothermal crystallization behavior and the higher order structure of the multi-sb-PLAs were investigated.

博士（工学）

京都工芸繊維大学

Poly(lactide) (PLA) is one of the bio-based polymers synthesized from renewable resources and has been expected to be replaced to the conventional fossil resource-based materials. Blending of two isomeric PLAs, poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA), leads to the stereocomplex (sc) formation. However, both hc and sc tend to co-exist in the simple blend of PLLA and PDLA. On the other hand, only sc tends to form in the block copolymer of L- and D-lactic acids (sb-PLA). In this study, oligo-D-lactic acids with various molecular weights were synthesized by the 1st ROP of D-lactide. Then tri-sb-PLAs were synthesized by the 2nd ROP of L-lactide using oligo-D-lactic acids as a macro-initiator. Further the chain extension reaction was performed for these tri-sb-PLAs to obtain multi-sb-PLAs. This method is characterized by the well controlled block length and composition of the resultant multi-sb-PLAs because they ought to be determined by the molecular weights of the starting PDLA and PLLA prepolymers. Although the total molecular weight of di- and tri-sb-PLAs are directly related to the block length, that of the multi-sb-PLA can be designed independently of the block length. So the effects of the block lengths and the total molecular weight of the multi-sb-PLA on the thermal property and the crystallization behavior can be examined separately.

14303甲第859号

http://hdl.handle.net/10212/2435

eng

ETD

Thesis or Dissertation

Thesis