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Simultaneous Stereocomplex Cocrystallization from Coexisting Two Types of Stereocomplexationable Poly(lactide) Systems

Abstract

Crystallization behavior of coexisting two types of stereocomplexationable poly(lactide) (PLA) systems, i.e., star-shaped four-armed stereo diblock poly(lactide) (4-LD) and linear one-armed poly(L-lactide) and poly(D-lactide) (1-L and 1-D, respectively) having the molecular weights similar to that of 4-LD [higher molecular weight 1-L(H) and 1-D(H)] and that of one block of 4-LD [lower molecular weight 1-L(L) and 1-D(L)] were investigated at different 4-LD content [X(4-LD)] values from 100 to 0 wt% fixing 1-L/1-D (w/w) = 50/50. The present article reports for the first time on simultaneous stereocomplex (SC) cocrystallization from coexisting two types of stereocomplexationable PLA systems (4-LD and 1-L/1-D blend). Solely SC crystallites were formed in 4-LD/1-L&1-D blends as well as unblended 4-LD or 1-L/1-D blends during crystallization from the melt, excluding 4-LD/1-L&1-D(H) with X(4-DL) = 25 % at Tc ≤ 120°C and 4-LD/1-L&1-D(H) blends with X(4-DL) = 0 % [i.e., 1-L&1-D(H) (50/50)] at Tc ≤ 140°C, wherein both SC and homo-crystallites were formed. The melting temperature values of 4-LD/1-L&1-D blends in the ternary blends indicate that 4-LD and 1-L&1-D cocrystallized simultaneously to form SC crystallites by intersystem interaction between PLLA block of 4-LD and 1-D or PDLA block of 4-LD and 1-L, irrespective of molecular weights of 1-L and 1-D and Tc. Interestingly, the SC crystallinity [Xc(S)] values of 4-LD/1-L&1-D were higher than those expected from the Xc(S) values 4-LD and 1-L/1-D blend, indicating that the blending star-shaped four armed stereo diblock 4-LD and linear one-armed 1-L and 1-D facilitated SC crystallization. The radial growth rate of spherulites values decreased with an increase in X(4-DL) and the crystalline growth mechanism was altered depending on X(4-DL).

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Publication details

The article was received on 19 Mar 2019, accepted on 12 Apr 2019 and first published on 12 Apr 2019


Article type: Paper
DOI: 10.1039/C9CE00403C
Citation: CrystEngComm, 2019, Accepted Manuscript

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    Simultaneous Stereocomplex Cocrystallization from Coexisting Two Types of Stereocomplexationable Poly(lactide) Systems

    H. Tsuji, K. Kikkawa, R. Ozawa and Y. Arakawa, CrystEngComm, 2019, Accepted Manuscript , DOI: 10.1039/C9CE00403C

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