Synthesis and Characterization of Well‐Defined Mid‐Chain Functional Macrophotoinitiators of Polystyrene by Combination of ATRP and “Click” Chemistry

A combination of ATRP and “click” chemistry is employed for efficient preparation of a novel well‐defined mid‐chain functional macrophotoinitiator of polystyrene. Bromo‐terminated polystyrene (PSt‐Br) is prepared by ATRP of styrene using a methyl‐2‐bromopropanoate initiator with CuBr/PMDETA. Subsequently, PSt‐Br is converted to PSt‐N₃ by a simple nucleophilic substitution reaction. A dialkyne‐functionalized photoinitiator (alkyne‐PI‐alkyne) is synthesized using a dihydroxy‐functional photoinitiator and propargyl bromide. Then the “click” reaction between PSt‐N₃ and alkyne‐PI‐alkyne is performed by Cu(I) catalysis. Spectroscopic studies reveal that low‐polydispersity polystyrene with the desired photoinitiator functionality in the middle of the chain (PSt‐PI‐PSt) is obtained.

     

Interface Strengthening of PS/aPA Polymer Blend Nanocomposites via In Situ Compatibilization: Enhancement of Electrical and Rheological Properties

The process of strengthening interfaces in polymer blend nanocomposites (PBNs) has been studied extensively, however a corresponding significant enhancement in the electrical and rheological properties is not always achieved. In this work, we exploit the chemical reaction between polystyrene maleic anhydride and the amine group in nylon (polyamide) to achieve an in-situ compatibilization during melt processing. Herein, nanocomposites were made by systematically adding polystyrene maleic anhydride (PSMA) at different compositions (1–10 vol%) in a two-step mixing sequence to a Polystyrene (PS)/Polyamide (aPA) blend with constant composition ratio of 25:75 (PS + PSMA:aPA) and 1.5 vol% carbon nanotube (CNT) loading. The order of addition of the individual components was varied in two-step mixing procedure to investigate the effect of mixing order on morphology and consequently, on the final properties. The electrical and rheological properties of these multiphase nanocomposite materials were investigated. The optical microscope images show that for PS/aPA systems, CNTs preferred the matrix phase aPA, which is the thermodynamically favorable phase according to the wettability parameter calculated using Young’s equation. However, aPA’s great affinity for CNT adversely influenced the electrical properties of our blend. Adding PSMA to PS/aPA changed the structure of the droplet phase significantly. At 1.5 vol% CNT, a more regular and even distribution of the droplet domains was observed, and this produced a better framework to create more CNT networks in the matrix, resulting in a higher conductivity. For example, with only 1.5 vol% CNT in the PBN, at 3 vol% PSMA, the conductivity was 7.4 × 10⁻² S/m, which was three and a half orders of magnitude higher than that seen for non-reactive PS/aPA/CNT PBN. The mechanism for the enhanced conductive network formation is delineated and the improved rheological properties due to the interfacial reaction is presented.     

Enzyme-linked immunosorbent assay (ELISA) with covalently bound protein on glass tubes: 1. Stable antigenicity and binding of IgG as a model antigen after repeated use

A modification of the ELISA procedure is described. The system is based on the covalent binding of protein to glass tubes. Human IgG was used as model antigen. Optimal conditions were tested for the removal of alkaline phosphatase-labeled antibodies from their antigen. Under such optimal conditions, a regenerable system could be created which exhibited many advantages, as compared with conventional ELISAs with antigens absorbed unspecifically to plastic surfaces. The advantages are: 1. A higher density of IgG as model antigen on the solid phase, i.e., 1 molecule IgG per 94 nm2 with glass tubes as compared with 110 nm2 with polystyrene (PS) or 143 nm2 with polyvinylchloride (PVC) microtiter plates. 2. A much smaller unspecific absorption of less than 1% as compared with 39% with PS-plates or 16% with PVC-plates treated under identical conditions. 3. A higher stability of the binding of the model antigen to the solid phase, i.e., a drastically reduced protein loss of less than 6% during the first ELISA procedure (including the regeneration) and of less than 1% during the subsequent ELISA and regeneration cycles with glass tubes as compared with 46% (PS plates) or 55% (PVC plates). 4. A smaller intraday variation coefficient of the ELISAs of 4.8% with glass tubes as opposed to 9.7% or 7.5% with PS or PVC plates respectively. The system with covalently bound antigens on glass tubes could be used in at least 20 consecutive measuring cycles. In five consecutive cycles, a protein loss of less than 5% was observed and the interday variation coefficient of the ELISA reaction was smaller than 5% using the same tubes repeatedly. Our results indicate that covalent linkage of protein can improve ELISA and lead to repeatedly usable systems as long as the antigen is stable against the regeneration procedure. Such an ELISA system may be helpful with highly purified proteins.     

多羟基苯乙烯树脂改性水性醇酸树脂的合成及性能

以多羟基苯乙烯树脂（PPSR）、季戊四醇（PE）、邻苯二甲酸酐（PA）、亚麻油酸（LA）和偏苯三酸酐（TMA）为原料制备水性醇酸树脂。通过红外、黏度、热重分析等手段对产物结构和热性能进行表征。结果表明：醇酸树脂的黏度、玻璃化转变温度（Tg）、热稳定性、耐水性和耐碱性随PPSR取代度的升高而增大。当PPSR取代度为100%时,所制备的醇酸树脂性能最好,表干时间0.67 h,实干时间3 h,硬度达2H,且具有较好的漆膜柔韧性。     

多模微波辅助的聚乙二醇化聚苯乙烯树脂制备

目的：研究一种微波辅助的聚苯乙烯树脂聚乙二醇（PEG）化的方法。方法使用PEG 200对市售Merrifield树脂进行修饰,尝试了不同条件下PEG化的效率。使用自行制备的PEG化树脂进一步衍生化,并进行氨基酸的负载,与市售王树脂进行比对。结果优选出了一套较为合适的反应参数,使用5 g树脂,50 ml PEG 200,微波功率600 W,预设温度170℃,照射15 min,共2次,获得了接近90%的负载率。衍生化得到PEG化王树脂后与氨基酸进行缩合,获得了令人满意的产率。结论本文首次报道了多模微波装置辅助的聚苯乙烯树脂PEG化,该方法操作简单,制备快速,条件温和,产率满意,远远优于传统制备方法。     

苝酰亚胺功能化聚苯乙烯乳胶粒水凝胶膜

将带有硼酸基团的苝酰亚胺荧光分子引入聚苯乙烯共聚乳胶粒表面,再将其嵌入聚丙烯酰胺水凝胶膜内,合成了对葡萄糖敏感的水凝胶膜。通过扫描电子显微镜、激光粒径分析仪对微球的外观形貌、单分散性进行表征,并用原子吸收光谱法间接测定了微球表面苝酰亚胺的含量,研究了苝酰亚胺功能化聚苯乙烯乳胶粒的紫外-可见吸收光谱图及其水凝胶膜的荧光性能。结果表明:苝酰亚胺功能化聚苯乙烯乳胶粒水凝胶膜经浓度逐渐增大的葡萄糖溶液浸泡后,其荧光强度降低,但发射峰位置不变。当葡萄糖浓度达到200 mmol/L时,其荧光淬灭效率为0.34。     

均聚物PS共混对PI-PS-PLA薄膜中微纳米结构的影响

将均聚物聚苯乙烯（PS）与三嵌段共聚物聚异戊二烯聚苯乙烯聚乳酸（PIPSPLA）以一定摩尔比共混,采用原子力显微镜（AFM）研究了均聚物浓度对其薄膜样品中微纳米结构的影响。结果表明：当n(PS)∶n(PIPSPLA)为1∶2和1∶1时,薄膜呈现出规则排列的柱状微结构,且柱状微区的尺寸较混合前的样品有所改变;当n(PS)∶n(PIPSPLA)为2∶1时,PS与嵌段共聚物PIPSPLA的分子链发生了相分离,其中均聚物PS相形成了较大尺寸的岛状微区。     

羧基丁苯-纳米氧化硅复合粉末增韧聚苯乙烯的研究

用直接分散聚合法制备了羧基丁苯-纳米氧化硅杂化胶乳,经喷雾干燥得到的羧基丁苯-纳米氧化硅复合粉末通过本体-悬浮聚合和熔融共混法制备了高抗冲聚苯乙烯.结果表明,本体/悬浮聚合法中预聚转化率的控制与复合粉末的加入量有关,当加入的复合粉末的质量分数为0.05时,冲击强度可提高5倍,也高于熔融共混法所制备的改性聚苯乙烯.本体/悬浮聚合法制备的改性聚苯乙烯的热分解温度（Td）高于熔融共混法改性的,且Td随复合粉末加入量的增加而提高,但改性聚苯乙烯的刚性有一定程度的降低,而对材料的玻璃化转变温度影响不大.     

Core/Shell Polystyrene/Magnetite Hybrid Nanoparticles Fabricated by Pickering Emulsion Polymerization and Their Magnetorheological Response

Soft‐magnetic polystyrene (PS)/Fe₃O₄ core/shell composite nanoparticles are fabricated by surfactant‐free Pickering emulsion polymerization using Fe₃O₄ nanoparticles as a solid stabilizer. The morphology of the synthesized PS/Fe₃O₄ particles consisting of a PS surface coated with Fe₃O₄ nanoparticles is examined by scanning electron microscopy and transmission electron microscopy. The thermal properties of Fe₃O₄ and PS/Fe₃O₄ are examined by thermogravimetric analysis, while the chemical bonding and composition of the nanocomposite are characterized by Fourier transform infrared spectroscopy and X‐ray diffraction. The magnetorheological (MR) properties of the PS/Fe₃O₄ composite nanoparticles dispersed in silicone oil are analyzed using a rotational rheometer under an external magnetic field. The PS/Fe₃O₄‐based MR fluids exhibit typical MR properties and a lower density compared to Fe₃O₄ nanoparticles, indicating the improved dispersion stability of the MR fluid compared to that of the Fe₃O₄ nanoparticle‐based MR fluid.     

Inversion of Phase Morphology in Polymer‐Blend Thin Films on Glass Substrates

Summary: The phase‐morphology inversion in two blend systems of polystyrene/poly(methyl methacrylate) (PS/PMMA) and polystyrene/poly(ε‐caprolactone) (PS/PCL) has been studied after their thin films were prepared on glass substrates by spin‐coating from a co‐solvent tetrahydrofuran (THF). Phase‐contrast microscopy (PCM), scanning‐electron microscopy (SEM) equipped with energy dispersive X‐ray spectroscopy (EDS), and atomic force microscopy (AFM) were used to obtain information on the morphology of the thin films during heat treatment. It was found that the PMMA‐rich and PCL‐rich phases are always continuous after annealing in either of the PS/PMMA and PS/PCL blend thin films, even though the PMMA and PCL are minor components in the blends. This should result from the better wetting abilities of PMMA and PCL on a glass substrate than PS in the blends. The effect of the viscosity in the evolution of the phase structure was also investigated by changing the molecular weight of PS in the PS/PCL blend thin films. Further more, it is found that the phase‐separation process and the wetting phenomenon of the blends on the glass substrate can be strongly suppressed after adding PS‐block‐PMMA diblock copolymer to the PS/PMMA blend system as a compatibilizer.

Scheme of the longitudinal section of the evolution of the phase structure of a PS:PMMA (70:30 w:w) blend film.