离子液体中疏水改性羟乙基纤维素的合成

采用大分子反应法,将疏水性单体l-溴代十二烷(BD)接枝到羟乙基纤维素(HEC)上,对羟乙基纤维素进行疏水改性,制备了疏水改性羟乙基纤维素(HMHEC)。研究了离子液体种类、反应温度、羟乙基纤维素浓度和BD用量对HMHEC性能的影响。最佳合成条件为:HEC浓度为3%(质量分数),溶解时间1 h,溶解温度100℃,反应时间2 h,反应温度80℃,BD用量为2 mL。在1-烯丙基-2-甲基-咪唑氯盐体系中合成的HMHEC性能好于在1-丁基-2-甲基咪唑氯盐中合成的HMHEC。     

改性羟乙基纤维素水溶液流变性能的研究进展

综述了经疏水化改性和阳离子化改性的羟乙基纤维素水溶液的流变学性能及其影响因素,如改性羟乙基纤维素的相对分子质量、溶液浓度、温度、侧链的种类、侧链链长、物质的量分数及其分布等;评述了表面活性剂与改性羟乙基纤维素形成复合体系溶液的流变性能。分析了由于改性羟乙基纤维素分子结构的改变而使其溶液体系增黏的机理。     

改性羧甲基羟丙基纤维素作聚醋酸乙烯乳液增稠剂的研究

用旋转粘度计研究了改性羧甲基羟丙基纤维素在聚醋酸乙烯乳液中的增稠效应。通过与非离子型羟乙基纤维素及离子型羧甲基纤维素的比较试验表明,改性羧甲基羟丙基纤维素用作聚醋酸乙烯乳液增稠剂有良好的增稠性、稳定性和配伍性。     

疏水改性纤维素醚在水包水含砂多彩连续相中的应用

制备纤维素醚/保护胶(Laponite)体系的水包水含砂多彩涂料,用疏水改性的纤维素醚(HMHEC)对其连续相增稠,探讨并分析了不同分子量以及不同用量的疏水改性的羟乙基纤维素醚对体系的贮存后状态和后增稠的影响;研究了HMHEC A搭配按不同比例混合的HASE和ASE对增稠体系稳定性的影响。结果表明:分子量低的疏水改性羟乙基纤维素醚HMHEC A搭配按1∶1混合的HASE和ASE在水包水含砂多彩体连续相增稠中达到很好的贮存稳定状态和防沉效果。     

超声波辅助阳离子羟乙基纤维素的合成研究

利用超声波辅助合成了阳离子羟乙基纤维素。结果表明,醚化过程中使用超声波,反应时间比传统湿法缩短一半,反应效率提高15%。通过红外、核磁等对产物的结构进行表征并用高效凝胶过滤色谱测定了其分子量及其分布。增稠性能实验表明,阳离子羟乙基纤维素具有很好的增稠效果。     

缔合增稠剂的增稠

缔合增稠剂是具有表面活性的聚合物。常用的是聚乙二醇醚的两端以，酯键各连接一个烷链，称之为亲油改性乙氧基化氨酯（HEUR）。它对乳胶漆的增稠机理与非缔合增稠剂不同。后者是以增大液体动力体积来使水相增稠的，而缔合增稠剂是通过自聚集以及与表面活性剂组成？昆合胶束，颗粒和颜料颗粒上亲油点缔合而使体系增稠的。这些聚集和缔合而形成的结构在剪切下会解开，在剪切力消失后又重新聚集和缔合，恢复了触变性，这是单靠液体动力体积增稠的非缔合增稠剂所没有的。图1是乳胶漆分别用羟乙基纤维素和HEUR调节到90KU后的粘度曲线。从图1中可见：用HEUR增稠的乳胶漆，在高剪切速率下比羟乙基纤维素增稠的有较高的粘度，这将有利于厚涂来补偿干燥后遮盖力的下降；在低剪切速率下有较低的粘度，这将有利于流平。     

水溶性N,O-羟乙基壳聚糖制备条件优化及其性能研究

以溴乙醇为羟乙基化试剂,NaOH为缩合催化剂,对壳聚糖进行改性并得到羟乙基壳聚糖(HECTS),研究了HECTS的水溶性及其与抗坏血酸和山梨酸的反应性能;用元素分析法(EA)确定了HECTS的羟乙基取代度(DS),并以取代度为基准,用正交实验优化了其制备条件;用FT-IR和~1H NMR表征了壳聚糖衍生物的结构。结果表明,碱化后的壳聚糖经溴乙醇改性可以生成N,O-羟乙基壳聚糖(N,O-HECTS),羟乙基取代度为82.42%及以上的N,O-HECTS在中性条件就具有较好的水溶性;当n(溴乙醇)∶n(壳聚糖单元)=5.0,n(NaOH)∶n(壳聚糖单元)=10.0,反应温度为50.0℃,反应时间为36.0 h时,N,O-HECTS的羟乙基取代度为112.39%,且该N,O-HECTS与抗坏血酸或山梨酸有良好成盐能力。     

羟乙基纤维素应用概况

羟乙基纤维素(以下简称HEC)在国外是纤维素醚类中工业化生产较早的品种之一。由于它具有增稠、悬浮、分散、乳化、粘合、成膜、保持水分和提供保护胶体作用等优良性能,一直广泛应用于各工业部门,至今新的用途仍在不断的发现,产量也在不断地增长。 羟乙基纤维素的生产是将纤维素先与碱和溶剂(水)相互作用而制成碱纤维素,然后再将碱纤维素与醚化剂反应,再经后处理而制成羟乙基纤维素。生产     

热缔合型阳离子纤维素的制备及性能

以羟乙基纤维素(HEC)、正丁基缩水甘油醚(BGE)和2,3-环氧丙基三甲基氯化铵(GTA)为原料,通过改变纤维素衍生物亲水基和疏水基的比例调控亲水-亲油平衡的方法制备了热缔合型阳离子纤维素(TACC)。首先,HEC与BGE反应制备了疏水化纤维素(HBPEC);然后,HBPEC与不同质量的GTA反应制备了4种不同GTA取代度的热缔合型阳离子纤维素(TACC)。采用FTIR、~1HNMR、元素分析对TACC进行了表征,证实TACC上已成功接枝了BGE和GTA。考察了GTA取代度、TACC质量浓度、NaCl浓度及剪切速率对TACC温敏增稠性能的影响。结果表明:40℃下,当GTA的取代度从0.12增加到0.32时,15 g/L的TACC水溶液的最大黏度(η_(max))从13 mPa·s增大到54 mPa·s,最大与最小黏度比(η_(max)/η_(min))从1.5增加到7.0,与最大黏度对应的温度(T_(max))从25℃升高到40℃;TACC浓度的增大使水溶液黏度及温敏增稠性能提高;相反地,NaCl浓度的增加会使TACC水溶液的黏度和温敏增稠性能降低,且会使T_(max)减小。     

亚什兰将在亚太市场推出全新Natrosol^TM Performax羟乙基纤维素

在2012年11月28～30日于广州举行的“中国国际涂料展”上，亚什兰推出了具有突破性涂料增稠技术的全新Natrosol Performax羟乙基纤维素。该产品系列是一种特殊的具备各种黏度规格的羟乙基纤维素增稠剂，能使涂料生产商在生产灵活性和质量控制方面获得全新的完美体验。该项技术使羟乙基纤维素颗粒在涂料低速剪切的条件下也能快速彻底地分散开。     

Study of rheological behavior of hydrophobically modified hydroxyethyl cellulose

Hydrophobically modified hydroxyethyl cellulose (BD‐HAHEC) was synthesized by the macromolecular reaction of hydroxyethyl cellulose (HEC) with bromododecane (BD). Study of the effects of polymer concentration, shear rate, temperature, and electrolytes on the rheological behavior of BD‐HAHEC indicated that the polymers had high viscosity, excellent viscosity retention in brine water, good thermal stability, and surface activity. Furthermore, investigation of the micromorphology of BD‐HAHEC solutions revealed the close relationship of rheological behavior and a hydrophobically associating effect. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3346–3352, 2006     

HMHEC/Gemini混合水溶液的性质及其稳定的乳状液

Gemini表面活性剂分子中包含两个亲水头基和两个疏水基团,其降低表面张力的能力优于传统表面活性剂,因此Gemini型表面活性剂与聚合物的相互作用也表现出不同于传统单链表面活性剂的特性。本文考察了Gemini型表面活性剂12-2-12与疏水改性羟乙基纤维素HMHEC之间的相互作用及其稳定乳状液的性质。     

Study on the rheological behavior of the hydrophobically modified hydroxyethyl cellulose with 1,2‐epoxyhexadecane*

Through the macromolecule reaction method, the hydrophobically modified hydroxyethyl cellulose (EP16–HAHEC) was synthesized using 1, 2‐epoxyhexadecane as the hydrophobic monomer. The solution properties of EP16–HAHEC were comprehensively investigated, which showed that the polymer with enhanced; viscosification property, thermal stability, shear resistance, and salt resistance was obtained. Amphiphilic structure of EP16–HAHEC molecules contributed to the surface activity of the polymer. By forming complex solution with surfactants or carboxylmethyl cellulose (CMC), the viscosification property of EP16–HAHEC could be enhanced through the interactions of hydrophobic groups and hydrogen bonds. The viscosity‐enhancing mechanism of HAHEC was studied by the environment scan electronic microscope (ESEM) and the fluorescence spectrum measurements, which demonstrated that the formation of the supramolecular aggregation networks was coincident with the increase of the apparent viscosity of HAHEC. With the gradual formation of the complete polymer molecule networks, the apparent viscosity rised dramatically, and the associating aggregations of the polymer molecules appeared far before the great change of the macroproperty of the polymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2953–2959, 2006     

疏水基团改性聚丙烯酸的缔合作用和流变行为

采用旋转黏度计测试系列疏水改性聚丙烯酸水溶液的流变性能,用稠度系数和流动指数表征聚合物水溶液的表观粘度。研究了聚合物在水中的增粘作用,以及pH、疏水单体含量和疏水单体结构的影响。结果表明聚合物水溶液呈非牛顿流体性质,疏水改性聚丙烯酸则表现出pH敏感性;在改性聚丙烯酸中,如苯氧基(3乙氧基)乙基丙烯酸酯中的疏水基团含量0.16%时,稠度系数为5.82,是纯聚丙烯酸的23.5倍;疏水基团碳数的增加显著提高其增粘作用。研究的结果可为含疏水改性聚丙烯酸在印染污水中应用提供理论数据。     

Rheological properties of semidilute solutions of poly(acrylic acid) modified with hydrocarbon and fluorocarbon end‐capped poly(ethylene glycol) macromonomer

Hydrocarbon and fluorocarbon end‐capped poly(ethylene glycol) (PEG) macromonomers with 9, 23, and 45 ethylene oxide units were synthesized by the esterification method. Copolymerization of these macromers with acrylic acid (AA) resulted in hydrophobically grafted poly(AA)s (PAAs) containing different lengths of PEG spacers. Their solution properties were investigated by rheological measurements and compared to those without hydrocarbon and fluorocarbon groups and without PEG spacers. Evident hydrophobic association was found to exist in the aqueous solution of these hydrophobically grafted copolymers, and the associating efficiency was improved by the flexible PEG spacer compared to those counterparts without them. However, the intramolecular association became predominant with the spacer length increase and the solution viscosity decreased. A wide viscosity plateau was observed for macromer modified polyelectrolytes in the alkalization process, which was unavailable for hydrophobically modified ones without PEG spacers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 12: 2777–2783, 2003     

Dilute solution properties of hydroxyethyl starch

The dilute solution properties of hydroxyethyl starch (HES) were examined by using the techniques of osmometry, light scattering, and viscometry. The molecular weight range was approximately 2 × 10⁶–0.06 × 10⁶. Since HES is a branched molecule, its properties were compared with those of two linear counterparts, ethyl hydroxyethyl cellulose and hydroxyethyl cellulose. The branching index g was estimated to be about 0.3 when calculated from the intrinsic viscosity, radii of gyration, and second virial coefficients.     

Structure and Property of Cationic Hydroxyethyl Cellulose

Through the macromolecule reaction, hydroxyethyl cellulose (HEC) was modified by quaternary ammonium monomer (GTAC) and the cationic HEC(C-HEC) with optimized viscosity was synthesized successfully. The structure of C-HEC was characterized by FTIR and Kjeldahl nitrogen content measurement. The introduction of cationic group onto the molecules of HEC resulted in the increase of the hydrophilicity of HEC. The dependence of the aqueous solution properties of C-HEC on the polymer concentration, GTAC dosage, additional electrolyte, temperature and shear rate were studied comprehensively.     

A study on the solution behavior of IPBC‐hydrophobically‐modified hydroxyethyl cellulose

Through the macromolecule reaction method, a series of 4‐isopropylbenzyl chloride (IPBC) hydrophobically‐modified hydroxyethyl cellulose (HAHEC) were synthesized. The use of suitable amount of hydrophobic monomer can ensure both the strong intermolecular association and good water‐solubility of HAHEC. Effects of polymer concentration, shear rates, temperature, and electrolytes on the solution behavior of HAHEC were comprehensively studied, which indicated that the polymers show high viscosification property, excellent viscosity retention in brine water, and surface activity. FTIR, DSC, and UV measurements were applied to characterize the molecular structure and composition of HAHEC to confirm the incorporation of hydrophobic group into the polymer chain. Atomic force microscope (AFM) and fluorescence spectrum measurements were applied to study the formation of the molecule aggregation and hydrophobic microdomain of HAHEC, and revealed the close relationship between the rheological behaviors and the hydrophobic viscosification effect. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2824–2831, 2006     

Functional modification of poly(vinyl alcohol) by copolymerizing with a hydrophobic cationic double alkyl‐substituted monomer

In this paper, a hydrophobic monomer (HM) that has a cationic double alkyl‐substituted group bonded to the nitrogen atom was first synthesized. Then a hydrophobic poly(vinyl alcohol) (PVA) was prepared by a radical solution copolymerization of vinyl acetate (VAc) with the HM followed by an alcoholysis reaction in alkaline conditions. The structures of HM and hydrophobically modified PVA (H‐PVA) were confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance. The effect of hydrophobic cationic segments on crystallization behaviors, mechanical properties, morphology, solution viscosity, and hydrophobic property were investigated. The results indicated that the crystallinity decreased from 37.2% of pure PVA to the minimum 23.2% of H‐PVA with the incorporation of 1.15 mol % HM. The thermal decomposition temperature of H‐PVA increased by about 50 °C compared with that of pure PVA. The viscosity of the H‐PVA solution was several times higher than that of the corresponding unmodified PVA solution over the whole shear rate range, which demonstrated that the H‐PVA had good shear‐resistance ability. Furthermore, the contact angle was significantly increased from 55.1° to 115° with the incorporation of only 0.83% HM, which illustrated that the H‐PVA had high hydrophobicity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43888.     

Synthesis and Properties of Temperature-Sensitive Hydrogel Based on Hydroxyethyl Cellulose

Hydrogels were prepared from modified hydroxyethyl cellulose by copolymerization with N-isopropylacrylamide. The equilibrium swelling ratio of hydrogel was measured in buffer solution with pH 7.0 from 25.0 to 45.0°C and the data obtained showed that hydrogels exhibited temperature sensitivity. The results of DSC analysis revealed that the low critical solution temperature (LCST) of hydrogels was enhanced by the introduction of hydroxyethyl cellulose. SEM images suggested that the cross-section of freeze-dried hydrogels was porous. The data of adsorption and release experiments for two model drugs suggest that the controlled drug release can be achieved.