Amphiphilic derivatives of carboxymethylcellulose: Evidence for intra‐ and intermolecular hydrophobic associations in aqueous solutions
Amphiphilic derivatives of carboxymethylcellulose: Evidence for intra‐ and intermolecular hydrophobic associations in aqueous solutions
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DOI：
10.1002/pen.21180
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发表时间：
2008-10
影响因子：
3.2
通讯作者：
R. R. L. Vidal-R.;R. Balaban;R. Borsali
中科院分区：
文献类型：
--
作者：
R. R. L. Vidal-R.;R. Balaban;R. Borsali
用静态(SLS)和动态(DLS)光散射、粘度计和流变学研究了CMC-g-聚(N，N-二己基丙烯酰胺)共聚物在水体系中的分子内和/或分子间缔合。采用自由基胶束共聚法合成了疏水基团摩尔分数为1~6%的共聚物。在不同的溶剂(0.5M NaCI、合成地层水(SFW)和Milli-Q水)中，作为聚合物浓度、疏水性、温度和离子强度的函数，评估了它们的缔合作用。结果表明，聚合物-聚合物之间的相互作用随着接枝在CMC主链上的疏水基团长度的增加而增加。疏水基团浓度最高(6mol%)的共聚物的特性粘数、重均摩尔质量(Mw)和流体动力学半径(RH)值最低，表明分子内疏水缔合使共聚物结构高度致密。共聚物在SFW中的流变行为表明，较高的聚合物浓度和较高的温度以及分子间的疏水相互作用和二价阳离子与羧酸基之间形成的桥梁不足以促进聚集体尺寸的显着增加。
The intra and/or intermolecular associations of CMC-g-poly(N,N-dihexylacrylamide) copolymers in aqueous systems were studied by static (SLS) and dynamic (DLS) light scattering, viscometry, and rheology. The copolymers containing 1 to 6 mol % of hydrophobic groups were synthesized by free radical micellar copolymerization. Their associations were evaluated in different solvents (0.5 M NaCI, synthetic formation water (SFW) and Milli-Q water), as a function of the polymer concentration, hydrophobicity, temperature, and ionic strength. Rheological behavior was investigated in SWF at 55°C. The results indicated that polymer-polymer interactions increase with the increase of the hydrophobic group lengths grafted onto the CMC backbone. The copolymer with the highest concentration of hydrophobic groups (6 mol %) had the lowest values of intrinsic viscosity, weight-average molar mass (M w ), and hydrodynamic radius (R H ), indicating a strongly compact structure due to intramolecular hydrophobic associations. The rheological behavior of the copolymers in SFW showed that the high polymer concentration and the high temperature together with the intermolecular hydrophobic interactions and the bridges formed between divalent cations and carboxilate groups were not enough to promote a significant increase in the size of the aggregates.