小粒径无皂阳离子聚苯乙烯胶乳纳米粒子的制备与稳定

采用溶剂热法,以AIBA为引发剂引发苯乙烯均聚,制得了小粒径的无皂阳离子乳胶纳米粒子。讨论了温度对乳胶粒径、反应时间对转化率的影响以及乳液的抗电解质稳定性,结果表明：采用溶剂热法制得的无皂阳离子聚苯乙烯乳胶粒子粒径约为25nm,分散均匀;随着温度的升高粒径先减小后增大;乳液的稳定性好。     

P（MMA—co—AA）乳液的制备及pH响应特性

以过硫酸钾(KPS)为引发剂、十二烷基硫酸钠(SDS)为乳化剂,利用正相乳液聚合制备(甲基丙烯酸甲酯-co-丙烯酸)共聚物(P(MMA-co-AA))乳液.通过测定聚合转化率和观察聚合过程稳定性,探讨了AA与MMA不同质量比时制备稳定的共聚物乳液的工艺条件;通过黏度法测定了乳液在不同pH时的相对黏度η,利用粒度分析仪分析了乳胶粒子在不同pH时的平均粒径和粒径分布.结果表明:AA含量较高时,控制聚合时间是得到稳定聚合物乳液的关键,当m(AA)/m(MMA)=12.5/100,65 ℃下反应120 min时,所制得的乳液稳定性最好.随着pH增大,乳液黏度先增大后降低;随着m(AA)/m(MMA)增加,制得的乳液pH敏感性增大;随着乳液从酸性(pH=5.17)变到碱性(pH=8.61),聚合物乳胶粒子平均粒径减小,粒径分布变窄.     

苯乙烯与甲基丙烯酸甲酯在聚乙二醇水溶液中无皂乳液共聚的粒径变化

利用高倍光学显微镜、库尔特粒径测试仪、TEM及zeta电位跟踪观测了苯乙烯(St)与甲基丙烯酸甲酯(MMA)在聚乙二醇(PEG)水溶液无皂乳液共聚过程中的粒径、粒径分布以及zeta电位变化.聚合物粒径会经历由小到大(某些粒径甚至超过1000μm,分布在0.04～2000μm的极宽范围内),再由大变小(形成的数均分布在0.04～0.18μm)过程,且粒径分布也由宽变窄,最终粒径数均分布集中在0.04～0.18μm窄范围内.结合聚合转化率数据,根据PEG水溶液中进行的St/MMA无皂乳液共聚粒径变化过程,以及zeta电位在聚合过程中异于普通无皂乳液的现象,认为该体系在反应初期形成的粒子会形成粒子堆,并随着聚合反应的继续,带有离子片段的自由基链段不断扩散进入粒子堆表面的小粒子,使其zeta电位不断增强,最终脱离粒子堆.提出了PEG水溶液中St/MMA无皂乳液共聚聚并脱析成核机理.     

水性聚氨酯甲阶酚醛水分散液微观形态及杂化膜的性能

以自乳化型聚氨酯和甲阶酚醛制备了聚氨酯 酚醛复合水分散液 .pH值与酚醛溶解度的关系表明甲阶酚醛的溶解是酚羟基电离的结果 .聚氨酯 甲阶酚醛水分散液粒子的形态有核壳结构、不完善的核壳结构及纯聚氨酯颗粒三种 ,后者粒径最小 .随着酚醛用量的增大 ,粒子平均粒径增大 .酚醛含量增加使体系热稳定性、机械稳定性、冻融稳定性及临界聚沉值下降 ,pH值稳定范围变窄 .分散液稳定性和电性能考察证明 ,本复合分散液的稳定性主要由分散液的电性能所决定 ,属真溶胶 ,但在一定程度上也具有大分子溶液的特性 .复合液涂膜的性能较纯聚氨酯有所改善 ,尤其在添加了硅溶胶之后     

醇醚糖苷与纳米膨润土颗粒稳定乳状液的协同作用

以表面活性剂醇醚糖苷(AEG)和纳米膨润土颗粒(NPT-2)为乳化剂,制备了油酸甲酯乳状液,考察了AEG与NPT-2的配比对乳液体系稳定性和乳液粒径的影响,并通过表面张力和zeta电位测量对二者复配稳定乳液的机理进行了讨论。结果表明,单一使用表面活性剂AEG或者纳米膨润土颗粒NPT-2均不能得到稳定的油酸甲酯乳状液,将二者复配则乳液的稳定性有显著提高。固定AEG量逐渐增加NPT-2乳液粒径先增大后又减小,固定NPT-2量逐渐增加AEG,乳液体系粒径逐渐变小;AEG与NPT-2复配前后体系的表面张力曲线"滞后"现象及zeta电位的升高表明,AEG分子在纳米颗粒NPT-2上发生了吸附,协同稳定乳状液。     

环氧树脂复合水分散乳液的制备及其性能研究

通过溶液聚合法制备了丙烯酸单体改性的高相对分子量的环氧树脂复合水分散乳液.利用傅立叶变换红外光谱仪测试了改性聚合物的结构,用ZETA电位分析仪测定了水分散液的粒径及其分布,用透射电子显微镜观察了乳液粒子形态.实验结果表明,改性树脂在水等极性溶剂中有较好的溶解性;随着改性树脂中羧基中和程度的加大,水分散液粒径减小,并成为形状规则的单分散乳液.作者同时进行了改性树脂稀释行为的研究.     

天然橡胶原位接枝炭黑的分散性研究

采用原位固相接枝方法,使在高温和强剪切作用下降解的天然橡胶接枝到炭黑表面.采用透射电镜(TEM)、原子力显微镜(AFM)等方法观察了接枝前后的炭黑粒子形貌变化,发现未接枝炭黑以微米级的附聚体形式存在,而由于炭黑聚集体被强剪切力部分破坏,接枝炭黑的聚集程度明显减弱,粒子的尺寸减小.采用激光光散射粒度仪对接枝前后炭黑的粒度进行分析,接枝炭黑的体积平均粒径为164 nm,远小于测得的原炭黑的粒径797 nm.采用沉降法、透光率法及zeta电位测量研究了接枝改性对炭黑在溶剂中的分散性及分散稳定性的影响,结果表明,接枝炭黑在接枝分子的溶剂中的分散性变好,分散稳定性提高.     

温度、pH敏感性核壳结构微凝胶的制备及性质

以无皂乳液分步聚合的方法, 将N-异丙基丙烯酰胺(NIPAM)与N,N-亚甲基双丙烯酰胺(MBA)交联反应3 h, 制得种子乳液, 再向种子乳液中加入甲基丙烯酸(MAA)功能性单体继续反应2 h, 制备了具有温度、pH敏感性的核壳结构微凝胶. 通过透射电子显微镜(TEM)、红外光谱(IR)等表征了微凝胶外貌形态及结构组成, 动态光散射(DLS)测定了微凝胶粒径响应热、pH的变化及微凝胶Zeta电位的变化. 结果表明凝胶形貌为异型核壳结构; Zeta电位与微凝胶粒径随温度、pH变化相关.     

生物亲和性壳聚糖-二氧化硅复合纳米粒子的合成及其吸附DNA特性研究

采用反相微乳液法制备了壳聚糖-二氧化硅复合纳米粒子,通过透射电镜（TEM）、红外光谱方法、Zeta电位实验等对所合成的复合纳米粒子的结构和性质等进行了表征.结果显示,基于壳聚糖与silica之间超分子作用所形成的复合纳米粒子呈规则的球形,粒径为50 nm左右,具有良好的单分散性和微孔结构,Zeta电位测定结果表明复合纳...     

沉淀法高效制备聚多巴胺纳米粒子

为得到分散性和稳定性较好的聚多巴胺纳米粒子,利用“沉淀-再分散法”高效制备了聚多巴胺纳米粒子水分散液。 首先利用溶液氧化法制备了分散在水/乙醇中的聚多巴胺纳米粒子,然后向分散液中加入丙酮使聚多巴胺纳米粒子絮凝。 收集沉降物,用丙酮冲洗并干燥后,加水重新分散得到纯化的聚多巴胺纳米粒子水分散液。 丙酮沉淀法得到的聚多巴胺纳米粒子形貌规整,分散性好,粒径分布在250 nm左右,在水中具有良好的储存稳定性和光热性能,与传统的超速离心提纯法相比,产率可提高57.4%。 此方法为其之后在药物载体及光热治疗等方面的应用研究提供了便利。     

Redispersibility of Acrylate Polymer Powder and Stability of Its Reconstituted Latex

The acrylate redispersible polymer powder (RPP) was produced from acrylate latex via spray drying, which was synthesized by latex polymerization with the configuration of soft core and hard shell. The powder's redispersibility and stability of its reconstituted latex were achieved through incorporating monomer methacrylic acid (MAA), which has functional carboxyl group and can provide an ionization effect in alkaline range. The influence of pH value and MAA amount on the redispersibility and stability were studied. The stabilization mechanism for reconstituted latex was also investigated. The acrylate RPP has good redispersibility at MAA of 4–5% and pH values between 9.0 and 10.0. The reconstituted latex is stable at these conditions due to high zeta potential and strong electrostatic repulsion force.     

Surfactant-free emulsion copolymerization of styrene and methyl methacrylate for preparation of water-redispersible polymeric powders

Poly(methyl methacrylate), polystyrene, and poly(styrene-co-methyl methacrylate) cationically stabilized latexes with up to 25% solid content were prepared by surfactant-free emulsion polymerization (SFEP) employing 1 mol % 2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride (VA-044) as an initiator and stabilizer (inisurf) with respect to monomer at 70 °C. The latexes had 200–500 nm z-diameter and a very narrow size distribution (PDI < 0.05). The stabilizing amidinium moieties from VA-044 were covalently bound to the particles. After drying in air, poly(styrene-co-methyl methacrylate), PS-co-PMMA latexes were easily redispersible in water simply by addition of water and a few minutes of gentle stirring. The redispersed latex particles had colloidal characteristics very similar to the original latex particles in terms of polydispersity, size, and zeta potential. In contrast, latexes prepared with a similar formulation but using a conventional cationic surfactant (CTAB) that was not covalently bound to the particles were not redispersible. This is the simplest method reported so far for the preparation of redispersible latexes that do not use high stabilizer concentrations. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2376–2381     

微乳液法制备球形氧化锆粉体及其分散特性的研究

以水/环己烷/曲拉通-100/正己醇四元油包水微乳体系中的微乳液滴为纳米微反应器，通过微反应器中增溶的锆盐和沉淀剂发生反应，可以制备出基本无团聚、球形度较好的纳米级氧化锆粉体，粉体粒径为30～40 nm且呈单峰分布。通过分析粉体中可溶性离子的含量及其在水中的电动行为以及悬浮体的流变特性，说明粉体具有良好的分散特性。     

选择性激光烧结高分子粉末的制备方法

综述了用于选择性激光烧结(SLS)的高分子粉末的制备方法。首先介绍了选择性激光烧结工艺对粉末在粒径、形貌、粒径分布、流动性等方面的性能要求,然后综述了常用的高分子粉末的制备方法包括机械粉碎法、直接聚合法、溶液法,以及一些较为新颖的粉末制备方法,如相分离法、微流体技术、"溶胀"粉碎法、水分散法,并对不同种类的高分子粉末的应用作了介绍。     

美托洛尔球形分子烙印聚合物的制备及吸附性能考察

以聚苯乙烯乳液为种球，以药品美托洛尔为模板分子，甲基丙烯酸为功能单体，二甲基丙烯酸乙二醇酯为交联剂，采用两步溶胀和种子悬浮聚合方法，通过优化反应条件，制得单分散性优良的球形分子烙印聚合物（molecularly imprinted polymers，MIPs）。重点讨论了致孔剂、分散剂和乳化剂的选择、搅拌速度对聚合物的粒径大小和分布、表观形态及吸附性能等的影响。通过聚合物对几种β-受体类药物分子的平衡吸附实验表明，MIP对模板分子美托洛尔具有良好的识别能力。     

Redispersible spray-dried nanocapsules for the development of skin delivery systems: proposing a novel blend of drying adjuvants

This study proposes a novel blend of drying adjuvants (lactose and polyvinylpyrrolidone) as an approach to produce dispersible powders containing nanocapsules for the development of skin delivery systems. Hydrogels were produced with liquid nanocapsules and spray-dried powders. Nanoparticle recovery was obtained after powder aqueous redispersion. No influence of the intermediate product was observed on the hydrogel properties and on the drug release profile. The novel blend of drying adjuvants is a smart approach to obtain dried nanocapsules with excellent aqueous redispersion and to maintain the drug release profile of the original suspension in the design of novel skin delivery systems.     

Tailoring of carboxyl‐decorated magnetic latex particles using seeded emulsion polymerization

In this research, submicron and carboxyl‐functionalized magnetic latex particles were elaborated by using seeded emulsion polymerization technique in presence of oil‐in‐water (o/w) magnetic emulsion as seed. The polymerization conditions were optimized in order to get well‐defined latex particles with magnetic core and polymer shell bearing carboxylic (–COOH) functionality. Starting from (o/w) magnetic emulsion as seed, synthesis process was performed by copolymerization of styrene (St) monomer with the cross‐linker divinylbenzene (DVB) in presence of 4,4′‐azobis(4‐cyanopentanoic acid) (ACPA) as a carboxyl‐bearing initiator. The prepared magnetic latex particles were first characterized in terms of particle size, chemical composition, morphology, magnetic properties, magnetic content, and colloidal stability using various techniques, e.g. particle size analyzer using dynamic light scattering (DLS) technique, Fourier transform infrared, transmission electron microscopy, vibrating sample magnetometer, thermogravimetric analysis, and zeta potential measurements as a function of pH of the dispersion media, respectively. The prepared magnetic latex particles were then used as second seed for further functionalization with methacrylic acid (MAA) in order to enhance carboxylic groups on the magnetic particle's surface. The results showed that final magnetic latex particles possessed spherical morphology with core‐shell structure and enriched carboxylic acid functionality. More importantly, they exhibited superparamagnetism with high magnetic content (58.42 wt%) and high colloidal stability, which considered as the main requirements for their application in the biomedical diagnostic domains. Copyright © 2017 John Wiley & Sons, Ltd.     

Physicochemical properties of structured phosphatidylcholine in drug carrier lipid emulsions for drug delivery systems

Drug carrier emulsions were prepared with structured phosphatidylcholine (PC-LM) which has both a long hydrocarbon chain and a medium hydrocarbon chain, and the characteristics of PC-LM as an emulsifier were investigated by measuring the creaming ratio, the surface tension of the emulsion system, and the mean particle size and zeta potential of the oil droplets in emulsions. The emulsion prepared with PC-LM as an emulsifier kept the condition and the ratio of separation was lower than those with purified egg yolk lecithin (PEL). The mean particle size of the emulsion prepared with PC-LM was smaller than that with PEL when using only sonication, approximately 250 nm. When using a high-pressure homogenizer after sonication, the mean emulsion size with PC-LM was also smaller than with PEL, approximately 150 nm. The surface tension of the various emulsions and the zeta potential of the emulsion droplets were measured to investigate the stability of the systems. In emulsions with PC-LM or PEL, the surface tension as an index of stability increased as the pressure of the homogenizer increased. Moreover, the zeta potential of the emulsion droplets prepared with PC-LM also increased with an increase in pressure of the homogenizer. As a result, it was found that the drug carrier emulsion prepared with PC-LM had significant advantages in terms of stability and mean diameter. We considered it could be used for the preparations of nanoparticle dispersion systems in drug delivery systems.     

Nitric acid oxidation on carbon dispersion and suspension stability

In this study, we have investigated the effect of nitric acid oxidation on the dispersion and suspension stability of activated carbon powder. We treated activated carbon powder with nitric acid at different concentrations. We measured the content of functional groups, the zeta potential and the powder particle size of the activated carbon powder with the Boehm titration, Fourier transform infrared spectroscopy, a zeta potential analyzer, and scanning electron microscopy. The results show that with the increase of nitric acid molar concentration, the content of acid functional groups increased, whereas the content of alkali functional groups decreased. At a nitric acid concentration of 10 mol/l, the surface‐modified activated carbon powder displays features such as the highest functional group content and zeta potential value, the smallest particle size, and the best dispersion and suspension stability in the solution. Copyright © 2008 John Wiley & Sons, Ltd.     

Aqueous dispersion behavior of drug particles by addition of surfactant and polymer

The effect of surfactant and polymer on dispersion stability of aqueous suspensions of 5-(3-ethoxy-4-pentyloxyphenyl)-2,4-thiazolidinedione (CT112) was investigated by measuring the adsorbed amount of surfactant and polymer, zeta potential, particle size, and sedimentation rate of CT112. The addition of celluloses rather than sodium dodecyl sulfate (SDS) provided a high stable suspension of CT112. In addition, mixed systems of celluloses and SDS enhanced CT112 dispersion more effectively. The mechanism of dispersion stability of CT112 by addition of SDS and celluloses is discussed.