Bulk Copolymerization of Conjugated Linoleic Acid With Styrene and Butyl Acrylate: Reactivity Ratio Estimation

Free radical bulk copolymerizations of conjugated linoleic acid (CLA)/styrene (Sty) and CLA/butyl acrylate (BA) were performed at 80°C. Copolymers were characterized for composition, conversion, molecular weights and glass transition temperature (T_g). A pseudo-kinetic model was developed and validated with experimental data. Reactivity ratios estimations were performed and one impurity commonly found in CLA, oleic acid, influenced the reaction kinetics significantly. The T_g of CLA homopolymer was predicted to be 5°C.     

In Situ Semibatch Emulsion Polymerization of 2‐Ethyl Hexyl Acrylate/n‐Butyl Acrylate/Methyl Methacrylate/Cellulose Nanocrystal Nanocomposites for Adhesive Applications

Cellulose nanocrystals (CNCs) are safe, “green,” hydrophilic nanoparticles. CNCs are added in situ during a semibatch 2‐ethyl hexyl acrylate (EHA)/n‐butyl acrylate (BA)/methyl methacrylate (MMA) emulsion polymerization. As EHA is a more hydrophobic monomer, manipulation of the monomer feed composition allows for the evaluation of the effect of hydrophobicity on CNC distribution in the nanocomposite and ultimately on adhesive properties. The adhesive properties (loop tack, peel strength, and shear strength) of three different EHA/BA/MMA latex formulations are shown to simultaneously improve with increasing CNC loading. However, the hydrophobicity of the EHA leads to a nonuniform distribution of CNCs in the latex films. Comparison of the in situ polymerized nanocomposites to their blended counterparts is also made.     

共轭亚油酸的结构、生理功能及来源

综述了共轭亚油酸的结构、生理功能及来源,并详细介绍了共轭亚油酸的合成.     

在无机SiO2纳米粒子存在下的苯丙乳液共聚合

研究了在无机SiO₂纳米粒子存在下的苯丙乳液共聚合.选择了能使苯丙乳液稳定存在的乳化剂体系,研究了温度和SiO₂的加入对聚合过程转化率的影响,结果表明,SiO₂的加入对聚合过程有阻聚作用,使单体的转化率降低.SEM照片证明SiO₂粒子已经进入苯丙乳液粒子中,而且SiO₂的加入对乳液制成的膜断面形态有一定影响.实验发现在无机SiO₂纳米粒子存在下,苯丙乳液共聚合时有较多残渣出现,对此通过改进乳液聚合进行了有效地改善.同时对制成的复合材料进行了力学性能和热学性能的测定.     

自交联共轭亚油酸囊泡的温敏膨胀行为

采用紫外辐照引发共轭亚油酸(CLA)囊泡内聚合反应,获得自交联CLA囊泡.用动态激光光散射(DLS)和冷冻透射电子显微镜(cryo-TEM)等观察自交联CLA囊泡的粒径和形貌变化,结果表明,自交联CLA囊泡的囊泡结构不仅不随温度变化解体,而且表现出明显的温敏膨胀性.自交联CLA囊泡体外释放5-氟尿嘧啶的实验表明其具有温度响应的缓释和控释特性.     

Initiation Efficiency Reduction in Semicontinuous Styrene and Butyl Acrylate Emulsion Copolymerization Reactions

The decrease of initiation efficiency (radical entry efficiency) during seeded emulsion copolymerizations of styrene and butyl acrylate with different residual monomer reduction strategies was evaluated. Experiments were carried out using 50 and 99wt.% of styrene in monomer feed stream. Simulations were performed with a detailed mathematical model of the process that takes into account the diffusion control of initiation, propagation and termination. Results showed that the radical entry into polymer particles is strongly influenced by the aqueous phase kinetics and by the monomer solubility in aqueous phase. Simulation results were compared to experimental results of residual monomer and showed that the residual monomer content can be reduced by a temperature increase at the end of the polymerization. However, an additional feeding of more initiator, even when combined with such an increase of temperature, did not lead to a smaller residual monomer content due, mainly, the kinetic of termination in aqueous phase and radical anchoring. A model that accounts for the reduction of initiator efficiency (free radical entry efficiency) was successfully used to explain the behavior of the experimental observations and was able to correctly predict the qualitative trends of the effectiveness of different residual monomer reduction strategies.     

共轭亚油酸与海藻酸钠囊泡化自组装纳米容器及其药物缓释性能

脂肪酸囊泡(FAV)是一类重要的纳米容器,然而其形成pH范围较窄且偏碱性环境,限制了其应用。 本文将共轭亚油酸(CLA)与海藻酸钠(SA)在近中性环境下共同自组装囊泡化纳米容器并提高其膜稳定性。动态激光光散射(DLS)和透射电子显微镜(TEM)结果表明,当SA质量分数为25%~50%时复合体系可在近中性条件下自组装形成50~250 nm尺寸的囊泡化纳米容器,且pH=7.4时随着质量分数增加囊泡化纳米容器直径增大。 根据SA和CLA在中性环境的物种存在形式推测,二者通过氢键作用驱动形成囊泡化纳米容器。 体外模拟释放实验表明,囊泡化纳米容器具有较高包覆率和较优缓释效果,有望应用于药物传输领域。     

共轭亚油酸制备方法的研究进展

依据反应机理和原料对具有生理活性的共轭亚油酸的制备与纯化方法进行了综述。详细讨论了共轭多烯酸(尤其是共轭亚油酸)的合成方法的研究进展，依据目标产物的收率、纯度及成本对合成或制备方法进行了比较和评价。     

有序介孔Ru-MgZr复合氧化物合成及催化亚油酸异构化性能

筛选高效、高选择性多相催化剂异构化亚油酸是共轭亚油酸(CLA)研究的重点。 本文采用溶剂挥发自组装改进的溶胶-凝胶法,合成有序介孔Ru掺杂的MgO-ZrO₂固体碱催化剂。 考察了催化剂中不同Mg物质的量对催化剂孔径、比表面积和表面碱性以及Ru等的结构和性能对催化性能的影响。 对比了催化剂的形貌、表面碱性及Ru组分对催化性能的影响程度。 结果表明,n(Zr)∶n(Mg)=3∶1时,Ru掺杂的MgO-ZrO₂固体碱催化剂具有高度有序的介孔结构和高的比表面积。 而n(Zr)∶n(Mg)=1∶1时, MgO-ZrO₂固体碱催化剂合成CLA产率较高,反应时间4 h,产率达到85%,催化效率为0.099 g(CLA)·L^-1(solvent)·min^-1,并且催化产物主要为具有生物活性的3种共轭亚油酸异构体。 催化剂的强碱性位点和晶格Ru是催化异构化反应的两个活性位点,强碱性位点是提高催化性能的关键。 固体碱复合氧化物催化效率高、制备方法简单、反应产物生物活性高等优点,具有较好的应用前景。     

非离子型可聚合聚氨酯/苯乙烯的超浓乳液聚合

研究了以非离子型可聚合聚氨酯(PUAG)和苯乙烯(St)为混合单体的超浓乳液聚合, 并且考察了n(NCO)/n(OH)摩尔比、复合乳化剂体系质量浓度[E]、不同乳化剂的种类、引发剂质量浓度[I]、单体体积分数(或分散相体积分数, 也称内相比Φ)、聚合温度等因素对聚合稳定性、动力学的影响. 同时结合光相关光谱(PCS)测定了聚合物乳胶粒子大小和粒径分布, 用透射电子显微镜(TEM)观察了粒子形态, 结果表明: 当n(NCO)/n(OH)＝2∶1, T＝328 K, Φ＝80.39%, [I]＝0.8% g/g (PUAG-St), [E]＝0.22 g/mL H₂O, m(MS-1)/m(CA)＝2∶1, PVA＝0.01 g/mL H₂O时, 超浓乳液不仅有较好的聚合稳定性和较快的聚合速率, 而且粒径小分布均匀. 同时, 在此条件下的表观动力学表达式和表观活化能分别确定为R_p＝k[I]^0.50[E]^0.73[M]^0.54和 E_a＝29.7 kJ/mol. 热失重分析(TGA)进一步表明: 调节PUAG的含量可以达到对聚苯乙烯的改性, 提高聚苯乙烯的热稳定性.     

S-亚基谷胱甘肽对亚油酸过氧化和苯乙烯聚合的抑制作用的研究

研究了S－亚硝基谷胱甘肽（GSNO）对偶氮二异丁腈(AIBN)引发亚油酸过氧化 和苯乙烯聚合的抑制作用。GSNO的抑制作用可能归结为反应中生砀氮氧自由基的抑 制活性。EPR证据表明,含有AIBN和GSNO的DMSO溶液在无氧和50 ℃下,生成了谷胱 甘肽巯基,2－氰基－2－丙基氮氧自由基。     

Formulation of Conjugated Linoleic Acid Microemulsion Using Mixed Nonionic Surfactants

A novel class of conjugated linoleic acid (CLA)-in-water microemulsion based on Tween80, EL-35, ethanol, and n-octanol was investigated as potential food delivery systems. The influences of pH on the microemulsion region were considered. The microemulsion structural transition was divided into water-in-oil (W/O), bicontionuous, and oil-in-water (O/W) microemulsion by conductivity and viscosity method. The microemulsion size and polydispersity were determined by dynamic light scattering (DLS). The size of O/W microemulsion droplets depends strongly on the contents of surfactants and CLA, and the diameter ranges from 22.1 to 30.7 nm and from 18.3 to 32.8 nm, respectively. All samples keep a remarkable stability in the experiments of 30 days. The stability of CLA in microemulsion and ethanol solution was determined by ultraviolet-visible spectrophotometry, the results revealed that the stability of the CLA in the microemulsion was increased remarkably.     

中空纤维两相液相微萃取技术用于芝麻中共轭亚油酸的测定

基于中空纤维两相液相微萃取提取新技术,建立了芝麻中共轭亚油酸的液相微萃取/高效液相色谱测定的新方法。通过研究萃取剂pH值、萃取时间和搅拌速率的影响,确定了最优化的液相微萃取条件:pH11.0的KOH溶液为萃取剂,萃取时间为30 min,搅拌速率为1 000 r/min。采用高效液相色谱法对共轭亚油酸进行定性和定量测定,结果表明,该方法的线性范围宽,相关系数(r2)为0.993,检出限(S/N=3)为17μg/L,相对标准偏差(n=6)为4.9%,共轭亚油酸的富集倍数为12.4倍。用于3种不同品牌芝麻中共轭亚油酸的分析,回收率为81.4%～94.8%。本法为植物中共轭亚油酸的分析检测提供了一种简捷有效的方法,可为乳品、植物油等其他复杂基质样品中共轭亚油酸的检测提供有效参考。     

单十二烷基磷酸酯辅助共轭亚油酸的囊泡化研究

以共轭亚油酸(CLA)为模型脂肪酸,与安全、温和的阴离子表面活性剂单十二烷基磷酸酯(MLP)进行复配,动态激光光散射和透射电镜表征结果表明,CLA在中性至弱酸性环境中仍然能够囊泡化.通过pH滴定曲线研究了CLA和MLP 2种分子的荷电物种随pH值的变化规律,据此分析各物种间的相互作用,并推断经MLP辅助CLA能够在中性至弱酸性环境中囊泡化的动因是CLA-MLP间的氢键或离子-偶极作用.     

单糖/双糖对近中性pH下共轭亚油酸囊泡影响的比较

比较了乳糖等3种双糖或核糖等3种单糖及其复配物对近中性范围共轭亚油酸(CLA)形成脂肪酸囊泡(FAV)的影响. 用激光丁达尔效应确定FAV的pH窗口及各相区, 用透射电子显微镜及动态光散射表征其形貌和尺寸, 用浊度法研究了其稳定性, 用等温滴定量热证明各种糖及其复配物与FAV表面的弱非共价键合作用, 并经理论计算获得结合能. 实验和计算结果表明, 各种糖及其复配物均可以双向拓宽CLA形成FAV的pH窗口, 且拓宽其近中性pH窗口的能力按照双糖<单糖≈双糖/单糖≤单糖/单糖的顺序依次增强. 主要归结为单糖在FAV表面的强竞争吸附, 以及双糖可能因多结合位点吸附而减少其自由羟基与环境水分子的缔合作用, 从而影响多羟基小分子依靠自由羟基增强囊泡表面亲水性的效果.     

苯乙烯本体聚合反应的动态光散射研究

首次用动态光散射方法跟踪了苯乙烯本体聚合全过程的光子丁关光谱，研究了散射哟度、聚合物平移扩散和、分子量分布随聚合反应的，获得了有关聚合系和活性分子链物理状态的信息，如玻璃态的微观非均一性及活性分子链比较刚硬等。     

Hybrid Miniemulsion Polymerization of Acrylate/Oil and Acrylate/Fatty Acid Systems

Acrylate–alkyd hybrid latex via miniemulsion polymerizations show promise as water‐borne coating systems. However, poor homogeneity of the particles caused by the immiscibility of the alkyd in polyacrylate limits monomer conversion and film formation. To resolve this problem, the hybrid miniemulsion polymerization of acrylate in the presence of linoleic acid and sunflower seed oil was carried out. Products were characterized by solvent extraction, dynamic light scattering, gel permeation chromatography (GPC), differential scanning calorimeter (DSC), and transmission electron microscopy (TEM). The results provide clear evidence that substituting a fatty acid or natural oil with smaller molecular size (weight) for a conventional alkyd improves the grafting efficiency, and enhances the homogeneity of the hybrid polymer particles in water‐borne latex systems.

     

Penultimate Propagation Kinetics of Butyl Methacrylate,Butyl Acrylate,and Styrene Terpolymerization

The pulsed‐laser polymerization technique is used to determine the composition‐averaged free‐radical propagation rate coefficient (k_p,ter) for terpolymerization of butyl methacrylate, butyl acrylate, and styrene between 60 and 120 °C. A significant deviation from terminal model predictions is observed for the ternary system, indicating that penultimate kinetics are important at these industrially relevant temperatures. The implicit penultimate propagation model, with all the coefficients taken from previous studies of the binary systems, provides a good prediction of the experimental k_p,ter results.

     

苯胺在十二烷基苯磺酸/水体系中的乳液聚合过程研究

利用光学显微镜和扫描电镜,对以水为介质、十二烷基苯磺酸(DBSA)为乳化剂的苯胺乳液聚合过程进行监测,发现苯胺在水体系中与DBSA反应形成DBSA-苯胺盐的棒状聚集结构,讨论了DBSA、苯胺、氧化剂的配比及浓度对聚合过程中棒状聚集结构的长度和数量及生成聚苯胺的电导率的影响,提出苯胺在DBSA/水体系中的乳液聚合反应是在胶束表面进行的,而棒状聚集结构中的DBSA-苯胺盐单体经水相扩散到乳胶粒子中,形成颗粒状的聚苯胺.     

利用烷基糖苷迁移和扩张共轭亚油酸囊泡pH窗口

脂肪酸囊泡(FAV)具有与脂质体类似的中空核壳结构, 且原料来源广泛, 绿色安全, 在包埋/缓释方面有重要意义. 但FAV对pH值依赖性强, pH窗口很窄并偏离生命体系适应pH范围, 限制了其作为包埋/缓释体在日用化学品及外用药等中的应用. 本文用绿色安全非离子表面活性剂烷基糖苷(APG)使共轭亚油酸(CLA)形成FAV的pH窗口从原先的8.0-9.0 迁移并扩张至6.0-8.0, 从而与生命体系适应pH值范围相匹配, 并探讨了改善FAV的pH值依赖性和敏感性的原理.