Living Radical Polymerization of Styrene Derivatives Containing Trialkylmetal Groups

Fourteenth group oganometallic styrene derivatives were synthesised by nitroxide-mediated controlled radical polymerization using di-tert butyl nitroxide (A-T) as initiator. This is the first time that nitroxide-controlled radical polymerization has been successfully adapted for the synthesis of new polystyrenes bearing organometallic species with controlled molecular weights and narrow polydispersities. Monomer reactivity ratios were determined in controlled nitroxide-mediated radical copolymerization between styrene and substituted styrene. All experiments permitted the synthesis of new organometallic polymers that will be used for the development of a polymer capsule for Inertial Confinement Fusion Experiments.     

Polymerizable Molecular Silsesquioxane Cage Armored Hybrid Microcapsules with In Situ Shell Functionalization

We prepared core–shell polymer–silsesquioxane hybrid microcapsules from cage‐like methacryloxypropyl silsesquioxanes (CMSQs) and styrene (St). The presence of CMSQ can moderately reduce the interfacial tension between St and water and help to emulsify the monomer prior to polymerization. Dynamic light scattering (DLS) and TEM analysis demonstrated that uniform core–shell latex particles were achieved. The polymer latex particles were subsequently transformed into well‐defined hollow nanospheres by removing the polystyrene (PS) core with 1:1 ethanol/cyclohexane. High‐resolution TEM and nitrogen adsorption–desorption analysis showed that the final nanospheres possessed hollow cavities and had porous shells; the pore size was approximately 2–3 nm. The nanospheres exhibited large surface areas (up to 486 m² g^?1) and preferential adsorption, and they demonstrated the highest reported methylene blue adsorption capacity (95.1 mg g^?1). Moreover, the uniform distribution of the methacryloyl moiety on the hollow nanospheres endowed them with more potential properties. These results could provide a new benchmark for preparing hollow microspheres by a facile one‐step template‐free method for various applications.     

Poly(sodium styrene sulfonate)-b-poly(methyl methacrylate) diblock copolymers through direct atom transfer radical polymerization: Influence of hydrophilic–hydrophobic balance on self-organization in aqueous solution

A series of poly(sodium styrene sulfonate)-b-poly(methyl methacrylate), PSSNa-b-PMMA, amphiphilic diblock copolymers have been synthesized through atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in N,N-dimethylformamide/water mixtures, starting from a PSSNa macroinitiator. The kinetics of the polymerization was followed by ¹H NMR, while the chemical composition of the copolymers was verified by a variety of techniques, such as ¹H NMR, FTIR and TGA. The MMA content of the copolymers ranges from 0 up to 60 mol%, while the number–average molecular weight of the PSSNa macroinitiator was 9000 g/mol. The self-association of the diblock copolymers in aqueous solution was compared to the respective behavior of similar random P(SSNa-co-MMA) copolymers through optical density measurements, pyrene fluorescence probing, dynamic light scattering and surface tension measurements. It is shown that the diblock copolymers form micellar structures in water, characterized by an increasing hydrophobic character and a decreasing size as the length of the PMMA block increases. These micelle-like structures turn from surface inactive to surface active as the length of the PMMA block increases. Moreover, contrary to the MMA-rich random copolymers, the respective diblock copolymers form water insoluble polymer/surfactant complexes with cationic surfactants such as hexadecyltrimethyl ammonium bromide (HTAB), leading to materials with antimicrobial activity.     

苯乙烯阴离子高温本体聚合引发机理的新发现(二)

采用创建的一种研究方法,以正丁基锂(n-BuLi)为引发剂,研究了苯乙烯(St)在60℃至140℃下的阴离子本体聚合.结果表明,低温下(＜20℃)以六元缔合结构形式存在的非活性正丁基锂在高温下(≥60℃)会转化为活性种.随机分布在该六元结构上的平均1.3个离子对可以引发St的阴离子聚合.然而从六元缔合结构上增长出的超分...     

基于HEA封端聚氨酯大孔树脂颗粒的合成、表征及水声声学性能

制备了丙烯酸-β-羟乙酯（HEA）封端的聚氨酯（PUA）大分子单体,采用正庚烷作致孔剂,用悬浮聚合法合成了聚氨酯-苯乙烯（PUA-St）及聚氨酯-苯乙烯-甲基丙烯酸乙酯-二乙烯基苯（PUA-St-EMA-DVB）AB-交联共聚物大孔树脂颗粒。SEM表明：合成的PUA-St-EMA-DVB颗粒含有规整的、孔径较大的孔洞,...     

Metal-free and base-free decarboxylation of substituted cinnamic acids in a deep eutectic solvent

Abstract

A metal-free and base-free strategy was developed in DES to synthesize styrenes for the first time by decarboxylation of cinnamic acid derivatives, which provided a renewable and cost efficiently protocol to access various styrenes including those with functional groups such as 4-vinylphenol and 1-chloro-4-vinylbenzene.     

C02（CO）8催化苯乙烯氢酯基化制α-苯基丙酸酯研究

以Co2（CO）8为催化剂,对苯乙烯与CO及甲醇氢酯基化反应制α-苯基丙酸甲酯的反应进行了研究,并根据实验结果提出了可能的催化反应机理．考察了催化剂用量、配体、溶剂、CO压力及反应温度等因素对氢酯基化反应的影响．结果表明：以甲苯为溶剂,在n（Co2（CO）8）／n（苯乙烯）=0．06,吡啶为配体且n（吡啶）／n（Co）=2,CO压力6．0MPa、反应温度95℃的较佳条件下反应12h,苯乙烯的转化率接近100％,α-苯基丙酸甲酯的收率达到89．07％,异正比24．35．     

EMI shielding and dynamic mechanical analysis of graphene oxide-carbon nanotube-acrylonitrile butadiene styrene hybrid composites

Carbon nanomaterials such as carbon nanotubes (CNTs), graphene and their hybrid have been studied extensively. Despite having excellent properties of CNTs and graphene have not yet been fully realized in the polymer composites. During fabrication agglomeration of CNTs and restacking of graphene is a serious concern that results in the degradation of properties of nanomaterials into the final composites. To improve the dispersion of CNTs and restacking graphene, in the present research work, we focused on the hybridization of graphene oxide and CNTs. Multiwalled carbon nanotubes (MWCNTs), functionalized carbon nanotubes (FCNTs), and graphene oxide-carbon nanotubes (GCNTs) reinforced acrylonitrile butadiene styrene (ABS) composites were prepared separately by vacuum filtration followed by hot compression molding. Further, dynamic mechanical analysis (DMA), and electromagnetic interference (EMI) shielding properties of ABS composites reinforced carbon nanofillers were investigated. The dynamic mechanical properties of polymers strongly depend on the adhesion of fillers and polymer, entanglement density of polymer chains in the presence of carbon fillers. The dynamic mechanical characteristics such as storage, loss modulus, and damping factor of prepared composites were significantly affected by the incorporation of MWCNTs, FCNTs, and GCNTs. Maximum EMI shielding effectiveness of −49.6 dB was achieved for GCNT-ABS composites which were highest compared to MWCNTs-ABS composites (−38.6 dB) and FCNTs-ABS composites (−36.7 dB) in the Ku band (12.4–18 GHz). These results depict the great potential of GCNTs-ABS composites to be used in various applications of efficient heat dissipative EMI shielding materials for electronic devices.     

基于苯乙烯和苯并噻二唑共聚场效应发光高分子材料的设计合成及性能研究

共轭高分子材料由于其优异的光电性能和可溶液加工等特性在有机光电器件中具有重要应用.本工作采用Stille偶联和Suzuki聚合反应,合成了两个由经典发光基元苯乙烯片段和共轭吸电子结构基元苯并噻二唑共聚的高分子材料聚（1,2-双（2,5-双（异辛氧基）亚苯基亚乙烯基-2,1,3-苯并噻二唑））（PVBT）和聚（1,2-双（2,5-双（正辛氧基）亚苯基亚乙烯基-2,1,3-苯并噻二唑））（nPVBT）.通过凝胶渗透色谱（GPC）、元素分析及差式扫描量热法（DSC）对PVBT和nPVBT两种高分子材料的结构及热稳定性进行表征,结果表明它们均具有良好的热稳定性,分解温度约380℃.由于烷氧基链的存在,两个材料具有良好的溶解性及成膜加工性.PVBT和nPVBT均表现出优异的发光特性,最大发射波长在590~605 nm范围,溶液下荧光量子产率为23%~35%,固态薄膜下量子产率为12%~20%.以这两个高分子材料薄膜作为活性层,所制备的顶栅-底接触型有机场效应晶体管器件显示出典型的p型电荷传输性能,空穴迁移率可达1.1×10^-4 cm²·V^-1·s^-1,开关比为10³~10⁴.本研究为发展高性能光电集成高分子材料提供了新思路,有望推动有机光电集成器件的研究.     

采用反应挤出三次加料法合成苯乙烯/异戊二烯/苯乙烯

以同向啮合双螺杆挤出机为反应器,采用苯乙烯和异戊二烯为聚合单体,以正丁基锂为引发剂,采用三次加料法合成苯乙烯/异戊二烯/苯乙烯(SIS)三嵌段热塑性弹性体.氢核磁共振(1H NMR)谱分析结果表明,共聚物中聚异戊二烯嵌段以1,4-结构为主.采用四氧化锇催化双氧水氧化降解聚合物分子链,利用凝胶渗透色谱对氧化降解后的聚苯乙烯碎片进行分析,证明共聚物分子为(聚苯乙烯-聚异戊二烯-聚苯乙烯)(PS-PI-PS)三嵌段结构.动态力学分析(DMA)及透射电子显微镜(TEM)分析结果表明,SIS具有两相分离结构.拉伸试验结果表明,共聚物拉伸强度与苯乙烯含量有关.