Synthesis of Hyperbranched Polyethylene with Poly(ε-caprolactone) Arms and Its Self-assembly in n-Hexane

doi:10.7503/cjcu20150634

Abstract

Abstract:

A novel polyolefin copolymer HBPE-PCLs with a hyperbranched polyethylene core and poly(ε-caprolactone) arms was successfully prepared via a combination of chain walking polymerization(CWP) and ring-opening polymerization(ROP). Hyperbranched polyethylene with hydroxyl ends(HBPE-OH) was firstly synthesized via the chain walking copolymerization of ethylene with 2-hydroxyethyl acrylate in the presence of Pd-α-diimine catalyst. The HBPE-OH was used as the macroinitior for ROP of ε-caprolactone to synthesize hyperbranched polyethylene copolymer HBPE-PCLs. Investigations of self-assembly of the HBPE-PCLs copolymer in n-hexane by means of transmission electron microscopy(TEM), scanning electran microscopy(SEM) and laser light scattering confirm that the copolymer formed vesicles in nonpolar organic solution. The vesicles are the organic counterparts to vesicles in aqueous solution and could potentially find analogous application in the encapsulation of drug and controlled release.

Key words: Hyperbranched polyethylene, Poly(ε-caprolactone), Vesicle

CLC Number:

O631

TrendMD:

SHI Xinbo, LI Lin, GAO Haiyang, WU Qing. Synthesis of Hyperbranched Polyethylene with Poly(ε-caprolactone) Arms and Its Self-assembly in n-Hexane[J]. Chem. J. Chinese Universities, 2015, 36(11): 2335.

Figures/Tables 10

Scheme 1 Synthetic routes employed for preparing HBPE-PCLs via a combination of CWP and ROP

Table 1 Results of chain walking copolymerization of ethylene with HEA

Sample^a	Yield/g	Hinc^b(%)	10^-3M_n	$N OH c$	M_w/M_n	Branch/1000 C^d
HBPE-OH₁₁	35.6	0.23	33	11	1.38	106
HBPE-OH₂₀	27.1	0.31	45	20	1.33	108

Table 1 Results of chain walking copolymerization of ethylene with HEA

Sample^a	Yield/g	Hinc^b(%)	10^-3M_n	$N OH c$	M_w/M_n	Branch/1000 C^d
HBPE-OH₁₁	35.6	0.23	33	11	1.38	106
HBPE-OH₂₀	27.1	0.31	45	20	1.33	108

Fig.1 1H NMR(A) and 13C NMR(B) spectra recorded in CDCl3 for macroinitiator HBPE-OH11

Table 2 Results of ring-opening polymerization of ε-caprolactone

Sample	c(CL)/(mol·L^-1)	Time/h	M_n	M_p	M_w/M_n
HBPE-PCL_11a	0.2	12	49	54	1.38
HBPE-PCL_11b	0.3	12	60	66	1.36
HBPE-PCL_11c	0.5	12	90	95	1.35
HBPE-PCL_20a	1	2	127	163	1.40
HBPE-PCL_20b	1	3	143	177	1.39
HBPE-PCL_20c	1	4	152	186	1.40
HBPE-PCL_20d	1	6	169	208	1.41
HBPE-PCL_20e	1	8	176	215	1.41

Fig.2 GPC traces of HBPE-OH11(a) and HBPE-PCL11b(b)

Fig.3 1H NMR(A) and 13C NMR(B) spectra recorded in CDCl3 for copolymer HBPE-PCL11b

Fig.4 TEM image of vesicles formed by the selfassembly of HBPE-PCL11b in n-hexane solution

Fig.5 SEM image of vesicles formed by selfassembly of HBPE-PCL11b in n-hexane solution

Fig.6 Typical Dh distributions obtained for 1 mg/mL n-hexane solutions of HBPE-PCL11b at 25 ℃ Average Dh=136 nm.

Fig.7 A possible molecular structures of the polymer vesicles in n-hexane

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