非离子表面活性剂对木质纤维素酶解的促进作用

纤维素酶单位酶活力较低、酶用量较高及酶自身易失活等因素依然是木质纤维素工业生产能源和生物基产品的瓶颈性问题。本文尝试在木质纤维素基质水解时添加一些非离子型表面活性剂以减少纤维素酶用量,并对这些非离子型表面活性剂促进酶解效率提高的原因进行了初步探讨。研究发现,添加非离子性表面活性剂能提高木质纤维素的酶解,添加浓度为0.05 g/g底物,常压甘油自催化预处理麦草经过添加两种非离子表面活性剂Tween-80和PEG 6000后葡萄糖产量分别可提高20%左右;非离子表面活性剂对不含木质素的原料酶解产糖也有较大的提高,以滤纸为底物时葡萄糖产量提高近90%,以微晶纤维素为底物时分别提高70%以上;添加非离子表面活性剂使得酶解体系中扩散系数k升高,异相反应效率提高,酶促反应动力学Km值明显减小,显著提高底物对纤维素酶的亲和力。     

松香改性非离子表面活性剂研究进展

松香是一种丰富廉价的可再生性天然资源。松香分子结构中的三环菲骨架和高级脂肪酸的长链烃基一样具有疏水基,并可通过其中的羧基、双键等活性基团引入亲水基,故松香可代替石油化工产品作为非离子表面活性剂的合成原料,符合当前绿色化学和可持续发展要求。综述了国内外松香基非离子表面活性剂的研究进展,讨论了该类非离子表面活性剂使用过程中的主要优势以及存在的问题,对该研究领域的发展前景进行了展望。     

非离子表面活性剂的结构与性能的关系

从非离子表面活性剂的结构出发,对非离子表面活性剂的表面吸附、表面张力、浊点、润湿与渗透、洗涤及泡沫性能做出了分析,并总结了非离子表面活性剂结构与上述性能之间的关系。     

烯丙基型可聚合表面活性剂的性能

通过对烯丙基型可聚合表面活性剂——烷基琥珀酸双酯磺酸钠的表面活性和应用性能的测定,研究和对比了两系列不同烷烃碳原子数(n)的烷基琥珀酸双酯磺酸钠的性能,得到了同系列产物结构与其性能的关系。结果表明,当n=8~16时,其中n=8,γcm c最低;n=16,cm c最低,分散力最强;n=14,乳化力最好;n=12,起泡性最好。     

含三嗪环非离子表面活性剂制备及其性能研究

以三聚氯氰、脂肪胺、聚乙二醇单甲醚(mPEG)为原料合成了6种均三嗪非离子表面活性剂。采用FTIR1、HNMR对中间体和目标产物进行了结构表征。考察了25℃时6种产品的表面张力、临界胶束浓度及其乳化力。结果表明,该类非离子表面活性剂具有较好的表面活性,其中DMAT-600的临界胶束浓度(cmc)和cmc下的表面张力(γcmc)分别可达0.162g/L和31.94mN/m;产品具有较强的乳化力,乳化力介于8.2~20.5min。     

非离子型表面活性剂对氯乙烯-水界面张力和保胶能力的影响

以聚乙烯醇/羟丙基甲基纤维素(KH20/60SH50)为主分散剂.非离子表面活性剂Span 60为助分散剂,考察氯乙烯悬浮聚合中油-水界面张力和保胶能力随非离子表面活性剂浓度的变化,发现非离子表面活性剂降低界面张力的能力和效率都强于主分散剂,但界面保胶能力不如后者;从Gibbs界面吸附公式和R值理论出发建立非离子表面活性剂、主分散剂在油-水界面上的竞争吸附模型,认为主分散剂/助分散剂混合使用时,助分散剂优先吸附于界面,在降低界面张力的同时也使分散体系保胶能力下降.     

新型可聚合硼酸酯表面活性剂的合成及其性能

以硼酸三乙酯、N-羟甲基丙烯酰胺、N,N-二羟乙基十二烷基胺等为主要原料,合成了新型可聚合非离子硼酸酯表面活性剂(BE),由IR和1HNMR进行表征和确认,并考察了产物的抗水解性、表面活性、均聚合及与丙烯酰胺的共聚合性能。结果表明:合成产物BE抗水解能力强,表面活性较高,pH=7时,cmc为0.066 mmol/L,γcmc为29.2 mN/m;BE有较强的均聚合和共聚合能力,产物特性黏度分别可达24.0 mL/g和80.0 mL/g以上;BE聚合产物也具有较好的表面活性,γcmc可达31.0 mN/m~32.4 mN/m,达到了常规低相对分子质量表面活性剂的表面张力水平。     

Atomic force microscopy and contact angle studies of polymerizable gemini surfactant admicelles on mica

Atomic force microscopy (AFM) was used to directly observe and characterize a polymer‐modified mica surface prepared using a polymerizable gemini surfactant. Normal tapping mode and contact mode AFM were used to image the treated mica surface morphologies in air and liquid environments, respectively. The root mean square (RMS) roughness of mica surfaces before and after surface modification and polymerization was analyzed from these scans. To determine the effect of styrene adsolubilization on the surfactant‐modified mica, AFM measurements of the modified mica were made at various styrene concentrations. Contact angle measurements were also made to further characterize the nature of the surfactant‐modified mica surface. The surface morphology and surface hydrophilicity were observed to be different for the modified mica after polymerization. In addition, the polymerized surface maintained its morphology after washing/desorption studies demonstrating the stability of the polymerized surfactant film. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of soap‐free cationic emulsion using polymerizable surfactant

A kind of polymerizable surfactant, methacryloyloxyethylhexadecyldimethylammonium bromide (DMHB) was used to synthesis soap‐free cationic emulsion with styrene (St), methyl methacrylate (MMA), and methacryloyloxyethyltrimethylammonium chloride (MATMAC) by emulsion polymerization using 2,2′‐azobis(isobutylamidine hydrochloride) (AIBA) as a cationic initiator. The effects of polymerizable surfactant concentration, initiator concentration, and reaction temperature on the conversion of monomer were investigated. The results indicated that the rate of polymerization could be expressed as R_p = k_p[AIBA]^0.42[DMHB]^0.45 and the apparent activation energy (E_a) was 83.42 kJ/mol. The particle size, ζ potential, and apparent charge density of cationic latices were also measured. The average diameter of copolymer particles decreased with increasing DMHB, MATMAC, and AIBA content; the charge properties of the particles were decided by the DMHB, MATMAC, and AIBA content. The polymerization mechanism is discussed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1111–1116, 2006     

Nanofiltration membranes prepared by direct microemulsion copolymerization using poly(ethylene oxide) macromonomer as a polymerizable surfactant

A novel polymer membrane with nanosized pore structures has been prepared from the direct copolymerization of acrylonitrile (AN) with a polymerizable nonionic surfactant in water‐in‐oil (w/o) or bicontinuous microemulsions. This polymerizable surfactant is ω‐methoxy poly(ethylene oxide)₄₀ undecyl‐α‐methacrylate macromonomer [CH₃O (CH₂CH₂O)₄₀ (CH₂)₁₁ OCO(CH₃)CCH₂, abbreviated: C₁‐PEO‐C₁₁‐MA‐40]. Besides PEO macromonomer, AN, and crosslinker ethyleneglycol dimethacrylate, the microemulsion system contained varying amount of water that formed w/o microemulsions having water droplet structures and bicontinuous microemulsions consisting of interconnected water channel. The polymerized membranes prepared in this study have pore radii ranging from 0.38 to 2.4 nm as evaluated by PEG filtration. The pore size appears to vary linearly with water content in precursor microemulsions. But a sharp change in the gradient of the linear relationship is observed around 25 wt % water content. Membranes made from bicontinuous (>25 wt % water) microemulsion polymerization have a larger and interconnected (open‐cell) nanostructures. In contrast, much smaller closed‐cell (disinterconnected) nanostructures were obtained from w/o (<25 wt % water) microemulsion polymerization and the membrane exhibited a permselectivity toward water in pervaporation separation of high ethanol (>50 wt %) aqueous solutions. The separation factor (α) for 95% ethanol aqueous solution by the membrane derived from the microemulsion containing 10 wt % water is about 20. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2785–2794, 2000     

非离子型聚醚改性三硅氧烷表面活性剂的合成表征及性能

选用EO(环氧乙烷ethylene oxide)链长为7~8, 平均相对分子质量为380的烯丙醇聚氧烷羟基醚(PE-38)和1,1,1,3,5,5,5-七甲基三硅氧烷(MD^HM)为原料, 通过无溶剂聚合, 在氮气保护下经Karstedt催化剂催化硅氢加成反应制备了非离子型聚醚改性三硅氧烷表面活性剂(NTS), 并通过傅里叶红外光谱仪和质子核磁共振仪验证了其结构。采用响应面法对合成工艺进行了优化, 确定了NTS的最佳合成条件为:n(C=C):n(Si-H)=0.93, 反应温度为94℃, 催化剂用量为6.4 mg·kg^-1, 在反应时间为2 h下, 经3次重复试验所得产品的平均表面张力为18.417 mN·m^-1, 与理论预测值基本相符。测试了产物NTS 0.1%(质量分数)的水溶液在pH为4、7和10的水溶液中的水解性能, 发现该产物在酸性和碱性条件下可稳定存放30 d左右, 在中性条件下可稳定存放60 d左右。     

Cloud point extraction of methylphenol in water samples with low viscosity of non-ionic surfactant Sylgard 309 coupled with high-performance liquid chromatography

A cloud point extraction method is developed for the extraction of methylphenol from various water samples using the non-ionic surfactant, Sylgard-309. Methylphenol in the water is a toxic element that is dangerous to humans. Hence, the treatment of water containing methylphenol is necessary. The method’s optimum conditions are 2.0 M salt concentration and 10% of surfactant concentration at room temperature. The limit of detection and limit of quantification of the method is 0.109 ppm and 0.365, respectively. The extraction recoveries of methylphenol in water samples (tap water, lake water, river water and sea water) are in the range of 90–99% with the relative standard deviations of less than 1.5%.     

Effect of cationic surfactant on homogenization and polymerization of methyl methacrylate miniemulsion modified by chitosan

Homogenization of monomer droplets and polymerization of methyl methacrylate (MMA) miniemulsion, stabilized by a combination of cationic surfactants including different amounts of n‐hexadecyltrimethylammonium chloride (HTMA) and chitosan 100, were investigated. With increasing HTMA concentration or decreasing concentration of chitosan 100, the required ultrasonication time for the miniemulsion to reach a critically stabilized state is reduced. After polymerization, for higher HTMA concentrations, droplet nucleation dominates because of higher surface coverage of HTMA on the droplets. However, for lower HTMA concentrations, the size distributions (SDs) of final latex particles are different from those of the droplets. Because surface coverage of HTMA on the droplets is lower in this condition, both droplet nucleation and homogeneous and/or micellar nucleation occur simultaneously in the miniemulsion polymerization. On increasing the concentration of chitosan 100 in the system, the SD of the final latex particles is far different from that of the droplets. This is due to a decrease of the effective surface coverage of chitosan 100 and HTMA on the droplets. Consequently, the opportunity of collision coalescence of the droplets increases, and MMA molecules can diffuse out more easily into the aqueous phase. Droplet nucleation is, therefore, no longer the major source for the latex particles. Copyright © 2006 Society of Chemical Industry     

Reactive surfactants in heterophase polymerization. VI. Synthesis and screening of polymerizable surfactants (surfmers) with varying reactivity in high solids styrene—butyl acrylate—acrylic acid emulsion polymerization

Several polymerizable surfactants (surfmers) have been used in the semi-continuous emulsion copolymerization of styrene, butyl acrylate, and acrylic acid. Three of the (anionic) surfmers (sodium 11-crotonoyl undecan-1-yl sulfate, sodium 11-methacryloyl undecan-1-sulfate, and sodium sulfopropyl tetradecyl maleate) were prepared in house with purities between 53 and 82%. Physicochemical properties such as the critical micelle concentration, the adsorption isotherm, and the specific adsorption area were determined. The surfmers were then used with constant addition profiles in semicontinuous reactions, and the instantaneous conversions of the main monomers determined. The particle size, amount of coagulum, surface tension, and stability against electrolyte solutions of the latices were evaluated. Films were cast of some of the latices, and the visual appearance and water adsorption were assessed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 183–1820, 1997     

剑麻皂苷的萃取与絮凝工艺优化研究

以剑麻膏为原料,考察了表面活性剂的种类及浓度、料液比、超声功率、萃取时间、萃取次数和浸泡时间对剑麻皂苷萃取的影响。确定较佳萃取条件为:十二烷基硫酸钠浓度0.025 8 mol/L,料液比1∶10(g∶mL),超声功率120 W,萃取时间40 min,萃取次数3次,浸泡时间4 h。同时考察了絮凝剂的种类及添加量、絮凝温度和复合絮凝剂对剑麻皂苷富集的影响。确定较佳絮凝条件为:100 mL剑麻皂苷萃取液中先加20 mL 1%聚合氯化铝,再加2 mL 0.1%阳离子聚丙烯酰胺的复合絮凝剂,絮凝温度50℃。对在较佳的萃取和絮凝条件下所得絮凝物进行水解,结果显示,该工艺得到的剑麻皂素的质量比传统工艺提高了15.5%,每生产1 g剑麻皂素酸用量减少了81.2%,COD排放量减少了96.5%。     

乳化剂浓度对苯乙烯乳液聚合成核机理的影响

以苯乙烯（St）为单体、十二烷基硫酸钠（SDS）为乳化剂、过硫酸钾（KPS）为引发剂,重点研究了该乳液聚合体系中乳化剂浓度（[S]）对胶束成核和沉淀成核的影响规律。结果表明,当SDS浓度高于CMC时（[S]≥ 8mmol/L）,体系的成核以胶束成核为主;当[S]=2mmol/L时,体系的成核以沉淀成核为主;当2mmol/L<[S]< 8mmol/L时,体系同时以沉淀成核和胶束成核两种方式成核,且胶束成核所占的比例随着SDS浓度的增加而增大。研究了聚合反应过程中SDS浓度对单位体积水中乳胶粒个数（Np）的影响规律：当[S]≥8mmol/L时,Np∝[S]0.9;当[S]<8mmol/L时,Np∝[S]0.8。     

Span80与丙烯酸酯化反应制备聚合型乳化剂

以H2SO4为催化剂、硅胶为吸水剂(S)进行丙烯酸(AA)和Span80的酯化反应,合成了聚合型乳化剂Span80丙烯酸酯。考察了催化剂用量、反应温度、吸水剂用量等反应条件对酯化反应酯化率的影响,确定了较理想的合成工艺条件:n(H2SO4)∶n(AA)∶n(Span80)=0.28∶1∶1、m(S)∶m(AA)=1.1∶1、酯化温度110℃。研究了该酯化反应动力学,确定该酯化反应为二级反应,表观反应活化能为57.83 kJ/mol。     

Submicron particle size and polymerization excess surfactant analysis by capillary hydrodynamic fractionation (CHDF)

The particle size distribution of a blend of two polymer latex monodisperse standards, 86 and 238 nm, has been measured by capillary hydrodynamic fractionation (CHDF). The particle size distributions obtained agreed well with the expected particle diameters. The relative amounts of the two standards in the blends were accurately measured at different blend ratios. The particle size distribution of a parenteral lipid sample was successfully measured. A soluble species was fractionated from latex standards smaller than 100nm. This soluble species appears to be excess surfactant used in the preparation of small size monodisperse latexes. The amount of excess surfactant increases as the particle diameter of the standard decreases.     

High solids content emulsions. III. Synthesis of concentrated latices by classic emulsion polymerization

Two different methods of producing bi‐ and trimodal latices of a mixture of methyl methacrylate, butyl acrylate, and small amounts of acrylic acid were tested. It is shown that a combination of concentrating blends of seed particles by semibatch reaction, followed by a nucleation of small particles plus a second semibatch phase allowed us to obtain stable latices with solids contents over 65% and viscosities of below 2500 mPa s^?1 with little coagulum formation. The key parameter in determining latex stability, coagulum formation, and viscosity appears to be the the particle size distribution, and especially its modification attributed to secondary nucleation. Because it is not possible to eliminate water‐soluble monomers from the polymerization recipe, secondary (homogeneous) nucleation must be minimized by careful addition of the free‐radical initiator and choice of monomer feed flow rates. The nucleation of the third population in the trimodal latices is best accomplished with a mixed surfactant system because renucleation by anionic surfactant alone leads to detrimental changes in the particle size distribution (PSD) resulting from excessive flocculation of particles. In addition, it was found that the viscosity of the final products was not sensitive to small changes in the ionic strength of the latex, although neutralization to a pH of 6 effectively doubles the final latex viscosity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1916–1934, 2002; DOI 10.1002/app.10513