凝胶色谱与多角激光光散射联用研究聚氧化乙烯的扩展效应和链构象

doi:10.7503/cjcu20150940

摘要/Abstract

摘要：

采用凝胶色谱与多角激光光散射联用的方法, 测定了一系列不同分子量的聚乙二醇(PEG)和聚氧化乙烯(PEO)在色谱柱中的扩展效应. 扩展因子随PEG/PEO分子量的增加而增大, 经扩展效应改正后得到了样品的准确分子量和分子量分布. 同时建立了PEO的Z均回转半径R_gz与重均分子量M_w之间的单分散标度关系: $R gz = 0.0272 M w 0.56$ , 结果表明, 长链PEO在水溶液中由于排除体积效应采取溶胀的无规线团构象.

关键词: 凝胶渗透色谱, 多角激光光散射, 聚氧化乙烯, 扩展效应, 链构象

Abstract:

The band broadening of aqueous gel permeation chromatography columns was studied by coupling with a multi-angle laser light scattering detector, using narrow polyethylene glycol(PEG) and polyethylene oxide(PEO) samples. The determined spreading factor of PEG/PEO increased with increasing molecular weight between 4.0×10³ and 1.3×10⁶. True molecular weight distributions of these samples were obtained with band broadening correction. Despite the presence of band broadening in the columns, the monodisperse scaling law between radius of gyration and molecular weight of PEO is established to be R_gz=0.0272 $M w 0.56$ , indicating that the long PEO chains take a swollen random coil conformation in water due to the presence of excluded volume effect.

Key words: Gel permeation chromatography, Multi-angle laser light scattering, Polyethylene oxide, Band broadening, Chain conformation

中图分类号:

O631.4

TrendMD:

李琦, 赵文杰, 赵梓良, 姬相玲, 薄淑琴, 刘勇刚. 凝胶色谱与多角激光光散射联用研究聚氧化乙烯的扩展效应和链构象. 高等学校化学学报, 2016, 37(4): 761.

LI Qi, ZHAO Wenjie, ZHAO Ziliang, JI Xiangling, BO Shuqin, LIU Yonggang. Band Broadening and Chain Conformation of Polyethylene Oxide by Gel Permeation Chromatography Coupled with Multi-angle Laser Light Scattering^†. Chem. J. Chinese Universities, 2016, 37(4): 761.

图/表 7

Table 1 Molecular weight of PEG/PEO samples as given by the suppliers

Sample	Supplier	10^-3 $M w, LS a$	10^-3 $M w b$	10^-3 $M n b$	M_w/ $M n b$
PEG3900	P.L.^c	4.00	3.91	3.78	1.03
PEG7800	P.L.	8.14	7.78	7.47	1.04
PEG8000	S.A.^d		8.0
PEG10000	S.A.		10.0
PEG12000	P.L.	12.3	12.0	11.3	1.07
PEO15000	P.L.	17.1	14.8	13.9	1.06
PEG20000	S.A.		20.0
PEO25000	P.L.	30.2	25.1	24.1	1.04
PEG35000	S.A.		35.0
PEO45000	P.L.	47.1	44.5	42.2	1.06
PEO75000	P.L.	82.0	74.6	71.0	1.05
PEO114000	P.L.	126.6	114.4	110.2	1.04
PEO190000	P.L.	203.9	190.3	177.3	1.07
PEO268000	P.L.	234.2	268.4	255.5	1.05
PEO293000	P.L.	313.0	293.2	278.0	1.05
PEO448000	P.L.	460.0	448.5	421.1	1.07
PEO686000	P.L.	635.0	686.5	628.0	1.09
PEO992000	P.L.	989.0	992.0	886.0	1.12
PEO1358000	P.L.	1243.0	1358.0	1179.0	1.15
PEO1000000	P.S.^e		1000.0

Table 1 Molecular weight of PEG/PEO samples as given by the suppliers

Sample	Supplier	10^-3 $M w, LS a$	10^-3 $M w b$	10^-3 $M n b$	M_w/ $M n b$
PEG3900	P.L.^c	4.00	3.91	3.78	1.03
PEG7800	P.L.	8.14	7.78	7.47	1.04
PEG8000	S.A.^d		8.0
PEG10000	S.A.		10.0
PEG12000	P.L.	12.3	12.0	11.3	1.07
PEO15000	P.L.	17.1	14.8	13.9	1.06
PEG20000	S.A.		20.0
PEO25000	P.L.	30.2	25.1	24.1	1.04
PEG35000	S.A.		35.0
PEO45000	P.L.	47.1	44.5	42.2	1.06
PEO75000	P.L.	82.0	74.6	71.0	1.05
PEO114000	P.L.	126.6	114.4	110.2	1.04
PEO190000	P.L.	203.9	190.3	177.3	1.07
PEO268000	P.L.	234.2	268.4	255.5	1.05
PEO293000	P.L.	313.0	293.2	278.0	1.05
PEO448000	P.L.	460.0	448.5	421.1	1.07
PEO686000	P.L.	635.0	686.5	628.0	1.09
PEO992000	P.L.	989.0	992.0	886.0	1.12
PEO1358000	P.L.	1243.0	1358.0	1179.0	1.15
PEO1000000	P.S.^e		1000.0

Fig.1 GPC-MALLS chromatograms of PEO448000 at a flow rate of 1.0 mL/min^The lines are Rayleigh ratios Rθ from the MALLS detector of 11 angles between 34.8° and 142.6°(from top to bottom is in the order of increasing angle).

Fig.2 Weight-averaged molecular weight Mw,i(A) and Z-averaged radius of gyration Rgz,i(B) of GPC fractions as functions of elution volume for PEO448000^The solid lines are polymer concentrationof GPC fractions as calculated from the refractive index detector signals, while the dashed lines are the LS signals at scattering angle of 90°.

Fig.3 Monodisperse calibration relation lnM of the GPC columns and the experimental relation lnMw of individual PEG/PEO samples^The monodisperse calibration relation lnM-V is showed as a long straight line, which is obtained by linear fit to the cross points [Vw, M(Vw)](solid circles). The experimental relations lnMw-V of PEG3900, PEG12000, PEO45000, PEO293000, and PEO1358000 are shown as short straight lines, which are obtained by linear fits to the GPC-MALLS data(open squares), and the corresponding cross points are encircled.

Table 2 Spreading factor σ02 and averaged molecular weights for PEG/PEO samples before and after band broadening correction(in parenthesis)

Sample	$σ 02$ /mL²	GPC			GPC-LS			GPC-LS-BBC
Sample	$σ 02$ /mL²	10^-3M_w	10^-3M_n	M_w/M_n	10^-3M_w	10^-3M_n	M_w/M_n	10^-3M_w	10^-3M_n	M_w/M_n
PEG3900	0.026	3.73	3.38	1.10(1.07)	3.63	3.48	1.04(1.07)	3.67	3.44	1.07
PEG7800	0.053	8.02	7.22	1.11(1.05)	7.83	7.64	1.02(1.05)	7.89	7.38	1.07
PEG8000	0.042	8.49	7.60	1.12(1.07)	8.30	7.98	1.04(1.07)	8.34	7.81	1.07
PEG10000	0.047	10.8	9.46	1.14(1.08)	10.6	10.1	1.05(1.08)	10.5	9.73	1.08
PEG12000	0.045	12.5	10.9	1.15(1.10)	12.3	11.5	1.06(1.10)	12.3	11.2	1.10
PEO15000	0.036	15.3	13.9	1.10(1.06)	16.0	15.4	1.04(1.06)	15.1	14.2	1.06
PEG20000	0.052	21.3	19.3	1.11(1.05)	20.6	20.2	1.02(1.05)	20.9	19.9	1.05
PEO25000	0.047	26.2	23.7	1.10(1.05)	25.8	25.1	1.03(1.05)	25.6	24.4	1.05
PEG35000	0.068	33.9	28.8	1.17(1.10)	32.3	30.7	1.05(1.09)	32.9	30.1	1.09
PEO45000	0.053	47.6	42.4	1.12(1.06)	46.7	45.3	1.03(1.06)	46.5	43.8	1.06
PEO75000	0.054	78.5	71.1	1.10(1.04)	77.0	75.6	1.02(1.04)	76.6	73.5	1.04
PEO114000	0.057	120.1	107.4	1.12(1.05)	119.4	116.8	1.02(1.05)	117.2	111.5	1.05
PEO190000	0.070	207.8	173.1	1.20(1.12)	205.8	194.1	1.06(1.11)	202.1	182.3	1.11
PEO268000	0.077	315.7	268.8	1.17(1.09)	306.3	295.7	1.04(1.08)	306.1	284.1	1.08
PEO293000	0.091	333.5	263.0	1.27(1.16)	319.0	295.0	1.08(1.14)	322.0	281.2	1.15
PEO448000	0.076	451.7	331.3	1.36(1.26)	430.1	368.4	1.17(1.23)	439.7	353.6	1.24
PEO686000	0.086	734.7	572.0	1.28(1.18)	690.7	627.0	1.10(1.16)	710.6	608.7	1.17
PEO992000	0.075	941.7	636.4	1.48(1.37)	897.7	718.8	1.25(1.32)	918.2	684.5	1.34
PEO1358000	0.089	1365.0	889.4	1.53(1.40)	1246.0	964.5	1.29(1.39)	1320.0	949.4	1.39
PEO1000000	(0.133)	981.0	339.2	2.89(2.53)	1068.0	474.7	2.25(2.53)	931.6	366.4	2.54

Table 2 Spreading factor σ02 and averaged molecular weights for PEG/PEO samples before and after band broadening correction(in parenthesis)

Sample	$σ 02$ /mL²	GPC			GPC-LS			GPC-LS-BBC
Sample	$σ 02$ /mL²	10^-3M_w	10^-3M_n	M_w/M_n	10^-3M_w	10^-3M_n	M_w/M_n	10^-3M_w	10^-3M_n	M_w/M_n
PEG3900	0.026	3.73	3.38	1.10(1.07)	3.63	3.48	1.04(1.07)	3.67	3.44	1.07
PEG7800	0.053	8.02	7.22	1.11(1.05)	7.83	7.64	1.02(1.05)	7.89	7.38	1.07
PEG8000	0.042	8.49	7.60	1.12(1.07)	8.30	7.98	1.04(1.07)	8.34	7.81	1.07
PEG10000	0.047	10.8	9.46	1.14(1.08)	10.6	10.1	1.05(1.08)	10.5	9.73	1.08
PEG12000	0.045	12.5	10.9	1.15(1.10)	12.3	11.5	1.06(1.10)	12.3	11.2	1.10
PEO15000	0.036	15.3	13.9	1.10(1.06)	16.0	15.4	1.04(1.06)	15.1	14.2	1.06
PEG20000	0.052	21.3	19.3	1.11(1.05)	20.6	20.2	1.02(1.05)	20.9	19.9	1.05
PEO25000	0.047	26.2	23.7	1.10(1.05)	25.8	25.1	1.03(1.05)	25.6	24.4	1.05
PEG35000	0.068	33.9	28.8	1.17(1.10)	32.3	30.7	1.05(1.09)	32.9	30.1	1.09
PEO45000	0.053	47.6	42.4	1.12(1.06)	46.7	45.3	1.03(1.06)	46.5	43.8	1.06
PEO75000	0.054	78.5	71.1	1.10(1.04)	77.0	75.6	1.02(1.04)	76.6	73.5	1.04
PEO114000	0.057	120.1	107.4	1.12(1.05)	119.4	116.8	1.02(1.05)	117.2	111.5	1.05
PEO190000	0.070	207.8	173.1	1.20(1.12)	205.8	194.1	1.06(1.11)	202.1	182.3	1.11
PEO268000	0.077	315.7	268.8	1.17(1.09)	306.3	295.7	1.04(1.08)	306.1	284.1	1.08
PEO293000	0.091	333.5	263.0	1.27(1.16)	319.0	295.0	1.08(1.14)	322.0	281.2	1.15
PEO448000	0.076	451.7	331.3	1.36(1.26)	430.1	368.4	1.17(1.23)	439.7	353.6	1.24
PEO686000	0.086	734.7	572.0	1.28(1.18)	690.7	627.0	1.10(1.16)	710.6	608.7	1.17
PEO992000	0.075	941.7	636.4	1.48(1.37)	897.7	718.8	1.25(1.32)	918.2	684.5	1.34
PEO1358000	0.089	1365.0	889.4	1.53(1.40)	1246.0	964.5	1.29(1.39)	1320.0	949.4	1.39
PEO1000000	(0.133)	981.0	339.2	2.89(2.53)	1068.0	474.7	2.25(2.53)	931.6	366.4	2.54

Fig.4 Dependence of the spreading factor σ02 on the molecular weight Mw of PEG/PEO samples^The straight line is a linear fit of σ02 on lgMw for all samples except PEO1000000.

Fig.5 Rgz as a function of Mw for PEO in water^PEO samples with narrow molecular weight distribution(solid squares); GPC fractions of PEO1000000(open circles); Devanand and Selser[15](upward-pointing triangles); Kawagichi et al.[16](downward-pointing triangles). The straight line indicates Rg,z=0.0272Mw0.56, while the dashed and short dashed lines are Rgz=0.0215Mw0.583 established in ref.[15] and Rgz=0.0202Mw0.580 obtained in ref.[16], respectively.

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