Synthesis and Self-assembly of Thermoplastic Elastomer Poly(ε-decalactone)-Poly(L-lactide)-PEG with Rare Earth Catalyst†

doi:10.7503/cjcu20160064

Abstract

Abstract:

Three triblock copolymers PLLA-PDL-PLLA with different compositions were synthesized by lanthanum tris(2,6-di-tert-butyl-4-methylphenolate) [La(OAr)₃] as the catalyst and 1,4-butanediol(BDO) as the initiator via a “one-pot two steps” block copolymerization strategy without PDL puriflcation. With biobased L-lysine diisocyanate(LDI) as the chain-extender, triblock copolymers were successively chain extended with biocompatible PEG6000 to produce multiblock copolymers. In tensile tests, the elongation at break of multiblock copolymers was up to 1200%, and they were good thermoplastic elastomers with an excellent mechanical property. In addition, the amphiphilic copolymers self-assembled into micelles in aqueous solution with a low critical micelle concentration(cmc) value of 4×10^-3 mg/mL.

Key words: ε-Decalactone, Rare earth catalyst, Multiblock copolymer, Thermoplastic elastomer, Micelle

CLC Number:

O632
O643

TrendMD:

WANG Xiaoqing, LING Jun, SHEN Zhiquan. Synthesis and Self-assembly of Thermoplastic Elastomer Poly(ε-decalactone)-Poly(L-lactide)-PEG with Rare Earth Catalyst^†[J]. Chem. J. Chinese Universities, 2016, 37(6): 1182.

Figures/Tables 13

Scheme 1 Synthesis of PLLA-PDL-PLLA triblock copolymer

Table 1 “One-pot two-step” synthesis of triblock copolymers catalyzed by La(OAr)3 in the presence of BDOa

Sample	n(BDO)∶n(DL)∶n(LLA) in feed	n(BDO)∶n(DL)∶n(LLA) in polymer^b	10^-3 $M n, NMR b$	10^-3 $M n, SEC c$	PDI^c
D₁₈-L₃₁	1∶20∶40	1∶18∶31	7.6	12.9	1.15
D₁₄-L₆₉	1∶59∶69	1∶14∶69	12.4	16.5	1.31
D₁₀-L₅₅	1∶10∶50	1∶10∶55	9.6	13.2	1.29

Table 1 “One-pot two-step” synthesis of triblock copolymers catalyzed by La(OAr)3 in the presence of BDOa

Sample	n(BDO)∶n(DL)∶n(LLA) in feed	n(BDO)∶n(DL)∶n(LLA) in polymer^b	10^-3 $M n, NMR b$	10^-3 $M n, SEC c$	PDI^c
D₁₈-L₃₁	1∶20∶40	1∶18∶31	7.6	12.9	1.15
D₁₄-L₆₉	1∶59∶69	1∶14∶69	12.4	16.5	1.31
D₁₀-L₅₅	1∶10∶50	1∶10∶55	9.6	13.2	1.29

Scheme 2 Structural formula of D18-L31

Fig.1 1H NMR spectra of D18-L31(a) and D18-L31-PEG(b) block copolymers

Fig.2 SEC traces of D18-L31(a), D14-L69(b), D10-L55(c), D18-L31-PEG(d), D14-L69-PEG(e) and D10-L55-PEG(f)

Table 2 Chain extension of triblock copolymers with PEG6000 by LDI in toluenea

Sample	n(D-L)∶n(PEG)∶n(LDI)^b	10^-3	PDI^c
D₁₈-L₃₁-PEG	1∶1∶2.2	109.7	1.73
D₁₄-L₆₉-PEG	1∶1∶2.2	78.7	1.59
D₁₀-L₅₅-PEG	1∶1∶2.2	90.6	1.59

Scheme 3 Synthesis of D-L-PEG multiblock copolymer

Fig.3 XRD(A) and DSC(B) curves of D18-L31-PEG(a), D14-L69-PEG(b) and D10-L55-PEG(c) multiblock copolymers

Fig.4 DMA storage modulus(E')(A), loss modulus(E″)(B) and tanδ(C) curves of D18-L31-PEG(a) and D14-L69-PEG(b) multiblock copolymers

Table 3 Tensile data for multiblock copolymers

Sample	w(PDL)(%)	Young’s modulus^a/MPa	Tensile stress^b/MPa	Tensile strain^c(%)
D₁₈-L₃₁-PEG	23	23	6.6	1200
D₁₄-L₆₉-PEG	13	60	6.4	880
D₁₀-L₅₅-PEG	11	123	7.5	410

Fig.5 Stress-strain curves of D18-L31-PEG(a), D14-L69-PEG(b) and D10-L55-PEG(c) multiblock copolymers

Fig.6 Particle size distribution of D18-L31-PEG(A) and D14-L69-PEG(B) micelles measured by DLS

Fig.7 Plot of fluorescence intensity ratio I338/I332 from the pyrene excitation spectrum vs. concentration for D18-L31-PEG

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