嵌段共聚物的合成及其组装行为

嵌段共聚物在选择性溶剂中可逆缔合形成以不溶性链段为核 ,溶解性链段为壳的胶束。广泛用作表面活性剂、增溶剂、药物载体和纳米材料等。综述了嵌段共聚物的合成方法 ,着重分析了浓度、温度、嵌段长度、溶剂、添加物及电荷等因素对嵌段共聚物在选择性溶剂中组装行为的影响及其形成机理。展望了嵌段共聚物组装行为的应用前景     

含氟丙烯酸酯嵌段共聚物的迁移行为及表面性能研究

利用原子转移自由基聚合(ATRP)法合成结构明确且含氟量相同的两种嵌段共聚物:甲基丙烯酸丁酯-b-甲基丙烯酸六氟丁酯(PBMA-b-PHFBMA)和甲基丙烯酸丁酯-b-甲基丙烯酸十二氟庚酯嵌段共聚物(PBMA-b-PDFHMA)。利用表面红外光谱和原子力显微镜研究了两种含氟嵌段聚合物以及它们加入到聚丙烯酸酯树脂中的迁移行为和表面性能。结果表明:对于含氟量相同的嵌段共聚物,具有较长含氟侧基的共聚物PBMA-b-PDFHMA比PBMA-b-PHFBMA的表面含氟量更高,表面自由能更低,且含氟侧链在薄膜表面呈针状垂直分布。含氟嵌段共聚物加入到聚丙烯酸酯树脂中后,混合树脂表面自由能降低明显,体现出明显的迁移行为;含氟嵌段共聚物的加入量在5%(wt)以上时,混合树脂的表面自由能趋于不变。在相同加入量情况下,具有较长含氟侧基的共聚物PBMA-b-PDFHMA比PBMA-b-PHFBMA降低表面自由能的作用更明显。     

结构明确含氟嵌段共聚物的设计合成及其在涂料中的应用新进展

含氟嵌段共聚物不仅具有含氟聚合物的耐候性、耐化学药品性、耐沾污性、低表面能等特性,而且表现出独特的两亲性,因此,近年来引起了国内外学术界和工业界越来越多的关注。本文首先对利用可控/活性自由基聚合法设计合成的结构明确的含氟嵌段共聚物进行了总结和评述,然后介绍了结构明确含氟嵌段共聚物的性能及其在涂料中的应用,最后对含氟嵌段共聚物在涂料领域的发展进行了展望。     

含氟丙烯酸酯乳液高疏水性与低氟含量的平衡探索

为了研究含氟丙烯酸酯乳液涂膜的疏水性与氟含量的平衡关系,以甲基丙烯酸十二氟庚酯(DFHM)为含氟单体,双丙酮丙烯酰胺(DAAM)和己二酸二酰肼(ADH)为交联单体,采用半连续核壳乳液聚合的方法合成了一系列自交联含氟丙烯酸酯共聚物乳液。研究表明:含氟单体含量为12%(即氟含量为6.84%,均以聚合单体的总质量计,下同)时,含氟基团在涂膜表面可以达到饱和,乳液固含量可达38.2%;再添加4%交联单体,涂膜的水接触角为116.6°。当含氟单体含量降为4%(氟含量2.28%)时,通过提高成膜温度或添加成膜助剂,也可使涂膜表面的水接触角达到104.2°,具有较好的疏水性能。     

ATRP法制备含氟嵌段共聚物P(MMA-HEMA-BA)-b-PFMA

原子转移自由基聚合(ATRP)法克服了传统自由基聚合法的这种缺陷,因而合成的聚合物可具备更加优异的性能。含氟嵌段共聚物的疏水性能优于含氟无规共聚物,目前ATRP法制备的含氟嵌段共聚物大多采用单一丙烯酸酯类单体与含氟单体制备而成,其涂膜性能较差,本文通过ATRP法,利用两步聚合先制备P(MMA-HEMA-BA)-Br大分子引发剂,再利用该大分子引发剂引发含氟单体聚合生成P(MMA-HEMA-BA)-b-PFMA,最终合成的含氟嵌段共聚物分子量分布为1.21,这表明该聚合过程可控性好。     

环氧乳液与含氟乳液的拼混研究

运用种子乳液聚合法制备了固含量(固体质量分数)为45%的含氟乳液;运用后乳化法制得了环氧乳液。ATR-FTIR测试表明环氧乳液与含氟乳液进行了有效的拼混。运用KrussK12型动态表面能分析仪测试了含氟涂膜对水和十六烷的接触角,对影响拼混乳液涂膜性能的因素如环氧树脂及其固化剂的比例、氟原子含量、成膜基材材质、成膜温度等进行了探讨研究。结果表明制备的含氟拼混乳液性能良好。     

表面活性剂结构对其在水-空气界面吸附性影响

研究了聚乙二醇-马来松香-聚乙二醇三嵌段共聚物和聚乙二醇-聚丙二醇-聚乙二醇三嵌段共聚物(P123)表面活性剂在水-空气表面的吸附行为并对结构的影响进行了评价。考察了不同结构对吸附行为的影响,包括临界胶束浓度(CMC),形态转变和吸附量。利用再定向理论研究了聚氧乙烯基表面活性剂在水-空气表面的吸附和形态转变过程。随着表面活性剂浓度的增加,在水-空气表面溶剂的物质的量分数降低,表面活性剂在水-空气界面上的物质的量分数增加。计算了吸附在表面上的两种状态表面活性剂的吸附量。吸附的自由能远小于胶束形成的自由能,表明表面活性剂优先吸附在表面上,达到饱和后就形成胶束。     

丙烯腈-丁二烯-苯乙烯树脂改性用丁苯嵌段共聚物的合成

以正丁基锂为引发剂、环己烷为溶剂、四氢呋喃为调节剂,在模试装置上合成了丙烯腈-丁二烯-苯乙烯(ABS)树脂改性用橡胶——丁苯嵌段共聚物,研究了反应温度与产品支化结构含量、相对分子质量与产品门尼黏度、凝胶质量分数、微观结构含量的关系。结果表明,随着聚合反应最高温度的升高,共聚物支化结构含量增大;当引发温度为55℃、反应最高温度为110～120℃时,产品支化结构含量约为5%,分子量分布约为1.12,其凝胶质量分数、微观结构含量与目标产品一致,丁苯嵌段共聚物的各项性能实测值符合ABS树脂改性用胶要求。     

含氟丙烯酸酯共聚乳液的合成与性能研究

由甲基丙烯酸甲酯(MMA)、丙烯酸丁酯(BA)和丙烯酸六氟丁酯合成了含氟三元共聚乳液.采用正交方法设计实验条件,并对实验结果以及乳液成膜性能进行探讨.FTIR、1H-NMR对共聚物的组成进行了定量分析,计算得出了共聚物中各组分的摩尔百分数.对三元含氟共聚物乳液涂膜的表面性能进行测量表明,共聚物氟含量直接影响着膜的表面性能.     

温度-pH双重敏感性嵌段共聚物胶束的制备及释药性能研究

RAFT法合成兼具温度-pH双重敏感性嵌段共聚物。以嵌段共聚物为载体,吲哚美辛为模型药物,透析法制备载药胶束并模拟在人体环境中的药物释放,考察载体的释药性能;FT-IR表征嵌段共聚物及载药胶束;UV法测定聚合物LCST及相变pH,并进行载药胶束的体外释药研究。一系列测试表明载药胶束在人体生理温度(37℃)下,酸性环境的药物释放速率和累积释放量要比碱性环境下小很多。嵌段共聚物兼具温度-pH双重敏感性,可作为药物载体,在药物缓释控释方面有潜在的应用。     

High performance coating films cured by novel penetrating method: Anionic resin paints

This study deals with a method of curing paint film at ambient temperature with a film-penetrative crosslinker. The method is based on the phenomenon that, after a wet coating film becomes thermoplastic, it is dipped in an aqueous solution of crosslinker. The crosslinker then penetrates into the film, and the film can be cured with the passage of dipping time. Herein an anionic copolymer containing diacetone acrylamide was employed as the main resin and carbohydrazide as the film-penetrative crosslinker. Cured films can be prepared with a short dipping time using this method. Excellent films were obtained when they were dipped in a suitable crosslinker solution containing the proper organic solvents (accelerator of penetration rate) and an appropriate acid (promoter of the reaction). In particular, the adhesion after the water resistance test was excellent compared with that of the coating film obtained by the two-component coating method.     

The study of diffusion of solvents from the coating films during the curing process by bulk acoustic wave admittance analysis

The diffusion of solvents from a coating layer and their evaporation at the surface of the coating film during the curing process of the coating are investigated by bulk acoustic wave (BAW) admittance analysis and can be expressed as change in the relative diffusion rate (J). The porosity and permeability of the coating film are related to the curing degree (η). The changes in J and the values of J₃ (the relative diffusion rate at the surface dry time, t_s), Δt_p (the time difference between the surface dry time t_s and the turning point time t_p when the diffusion behaviour changes), and η can provide much useful information on selecting solvents and optimizing coating ingredients in the preparation of coatings. The effects of the coating film thickness, solvent content of the coating liquid, and the volatility of the solvent on the diffusion of solvent from the film are also discussed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 563–571, 1997     

Preparation and characterization of sol–gel Al2O3/Ni–P composite coatings on carbon steel

Ceramic films have been applied to improve the resistance against high temperature oxidation of carbon steels. Alumina film was prepared on carbon steel surface by a dip coating technique. Electroless Ni–P plating film has been pre-deposited as an intermediate layer to improve the adherence of the film to carbon steel substrate. The oxidation kinetics of coated sample was investigated by measuring weight gain at 800 °C for 100 h. The surface and cross-section morphology of samples before and after oxidation were characterized by scanning electron microscopy (SEM). The composition and element distribution at the interface of the coated samples were analyzed by energy dispersive spectroscopy (EDS) and EMAX.The results show that the composite coating is uniform. The alumina coating adhesion strength to the substrate is up to 20 ± 2 N in scratch test because the alumina film presents interdiffusion of nickel and aluminum during heat treatment. The oxidation resistance test indicates higher oxidation resistance of as-coated carbon steel comparing to uncoated ones.     

Facile fabrication of elongated polymer micro/nano discs and their surface adhesiveness

The key factor of polymer particles using as a drug carrier is the ability to adhere to the surface of the target sites in order to optimize the drug delivery efficiency. To this end, shape of the particles is one of the essential parameters since nonspherical particles such as discs theoretically have more contact surface area than spherical particles. We herein propose a facile method to fabricate elongated polymer micro/nano discs by combining phase separation and a roll-to-roll coating process with a stretching method. By roll-to-roll coating, biodegradable poly(lactide-co-glycolide) (PLGA) discs formed on polyvinyl alcohol (PVA) film can be instantly stretched by uniaxial stretcher. The effect of stretching temperature and percentage of film elongation on the particle morphology was studied. The results showed that the PLGA discs can be elongated and the aspect ratio of 2.3 can be achieved with 600% elongation at 80°C, reflecting the increase of estimated contact surface area by 1.8 times. The adhesion efficiency of these elongated discs was compared with discs before stretching, spheres, and elongated spheres by using the water-dropping test. The elongated discs showed the best result among these particles and their adhesion efficiency are strongly related to estimated contact surface area.     

Interface morphology snapshots of vertically segregated thin films of semiconducting polymer/polystyrene blends

We present atomic force microscopic images of the interphase morphology of vertically segregated thin films spin coated from two-component mixtures of poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene-vinylene] (MEH-PPV) and polystyrene (PS). We investigate the mechanism leading to the formation of wetting layers and lateral structures during spin coating using different PS molecular weights, solvents and blend compositions. Spinodal decomposition competes with the formation of surface enrichment layers. The spinodal wavelength as a function of PS molecular weight follows a power-law similar to bulk-like spinodal decomposition. Our experimental results indicate that length scales of interface topographical features can be adjusted from the nanometer to micrometer range. The importance of controlled arrangement of semiconducting polymers in thin film geometries for organic optoelectronic device applications is discussed.     

环氧-胺/环氧-丙烯酸酯复配阴极电泳涂料

合成了环氧-胺阳离子树脂和环氧-丙烯酸酯接枝阳离子树脂,以这2种树脂共混制备了有机挥发物含量低的复配树脂用作水性汽车阴极电泳涂料。采用FTIR、DSC、TG和SEM分析研究了几种树脂的化学结构、影响漆膜玻璃化温度(Tg)、热稳定性等的因素并对漆膜的的表面形态和断面形态进行了观测。结果表明,复配树脂漆膜的综合性能最好;当环氧-丙烯酸接枝树脂的质量分数为80%时,复配漆膜有单一的Tg,说明2种树脂相容,从而对提高复配漆膜的综合性能起到协同作用。     

Polyaniline Coating on Iron–Synthesis and Characterization

Protective coating has been used widely for metal corrosion control. Polyaniline (PANi) films can be electrosynthesized by oxidation of aniline on a metal surface from an aqueous acid medium. In this study, an iron surface was coated by polyaniline thin film. While iron easily oxidizes in acid solutions, the electropolymerization reactions were carried out in dilute acidic media. Rust, fats, etc. on the surface of iron were removed by alkali-ethanol solution, dichloroethylene, and, finally, hydrochloride (HCl) solution (10%), respectively. Coating was carried out in different potential (1.0, 1.5, and 2.5 V). To observe the effect of elemental contents of iron samples, spectral analysis also was taken before electropolymerization. Especially, effects of chromium and nickel elements were investigated. Physical resistance of the coating was examined by “band test.” Dissolving and defective coatings were also tested in acidic solutions and common organic solvents. In addition, to observe the morphology of coating, photos of samples were taken by scanning electron microscope (SEM) and metal microscope (MM).     

温致变色涂料制备及变色性能研究

以三芳甲烷类隐色体染料为发色剂,配合显色剂和溶剂合成了适用于织物应用的温致变色涂料。考察了溶剂复配,发色剂、显色剂、溶剂种类对温变涂料颜色及颜色变化的影响。探讨了添加涂料对温变涂料颜色调节作用。结果表明,在温变涂料中添加涂料能有效改变温致变色涂料颜色并且不影响其温致变色能力和变色温度;发色剂、显色剂、溶剂间极性不同会破坏温变涂料温变色能力;制备温变涂料所用溶剂为十六醇与十二醇质量比4∶1和3∶2时,温变涂料变色温度分别为42℃和36℃,说明改变溶剂比例能有效调控温变涂料变色温度。     

PP塑料底材处理剂的研制及应用

以氯化聚丙烯为主要原料,制备了一种环保型的聚丙烯塑料底材表面处理剂。讨论了树脂基料、溶剂、乳化剂的选取及配比等因素对涂层附着力的影响,确定了处理剂的最佳配方。经试验测试,聚丙烯塑料表面经处理剂处理后,其涂层的附着力显著提高。     

汽车用镁合金磷化处理及化学镀Ni-Sn-P合金镀层

先对汽车用AZ31B镁合金进行了磷化处理,然后在磷化膜表面化学镀Ni-Sn-P合金镀层,并对化学镀Ni-Sn-P合金镀层的成分、表面形貌及耐蚀性等进行了研究。研究发现:镁合金磷化属于一种磷化膜生成和溶解的动态过程。磷化膜较为均匀、致密,存在少量微裂纹,厚度约为6μm。化学镀Ni-Sn-P合金镀层由大量均匀、致密的胞状颗粒堆积而成。经过磷化和化学镀Ni-Sn-P合金镀层后,镁合金的耐蚀性显著提高。