Functionalized Biocompatible Poly(N‐vinyl‐2‐caprolactam) With pH‐Dependent Lower Critical Solution Temperature Behaviors

Functionalized temperature‐ and pH‐sensitive poly(N‐vinyl‐2‐caprolactam) (PVCL) polymers are prepared by copolymerizing monomers of N‐vinyl‐2‐caprolactam (VCL) and a VCL derivative, 3‐(tert‐butoxycarbonyl)‐N‐vinyl‐2‐caprolactam (TBVCL). Different molar compositions are studied, with the functional monomer at 9 and 14 mol%, respectively, (COOH‐PVCL9 and COOH‐PVCL14). Sharp, complete, and reversible phase transitions of the copolymers with little hysteresis are shown to be pH‐dependent, with cloud points ranging from 35 to 44 °C for COOH‐PVCL9, and 29 to 64 °C for COOH‐PVCL14, upon pH change from 2.0 to 7.4. Cytotoxicity assay demonstrates that the functionalized PVCL copolymers are biocompatible with NIH/3T3 up to 2 mg mL^?1. Such new PVCL‐based water soluble copolymers with tunable properties could be useful in a variety of biomedical applications.     

Chloride Ion-Containing Polymeric Ionic Liquids for Application as Electrolytes in Solid-State Batteries

Organic, solid-state batteries require efficient solid electrolytes able to provide stable ion conduction. Here, solid electrolytes based on ionic liquid (IL) polymers with chloride counterions as electrolyte materials for batteries are presented. Acrylic monomers with imidazolium substituents with alkyl side groups that are linked by alkyl spacers to the acrylic group are employed. The IL monomers with chloride counterions are either converted by thermally initiated radical polymerization into linear homopolymers or incorporated into polymer networks by UV-initiated copolymerization utilizing a bifunctional, non-ionic cross-linker. Both procedures successfully yielded the desired materials, which is confirmed by NMR spectroscopy (linear homopolymers) or Raman spectroscopy (IL networks). The ionic conductivities at room temperature are measured by Electrochemical Impedance Spectroscopy. The ionic conductivities of the linear homopolymers are in the range of 10⁻⁴ to 10⁻⁶ S cm⁻¹, while those of the IL networks are about two orders of magnitude lower. They increase to 10⁻⁴ S cm⁻¹ at 70 °C. The electrochemical stability is examined by Linear Sweep Voltammetry and is proven in the voltage range of −2 to +2 V. The results reveal that the materials represent promising electrolytes for potential solid-state battery applications.     

Base Catalyzed Thiol–Ene Click Chemistry toward Inner CHCF Bonds for Controlled Functionalization of Poly(vinylidene fluoride)

A facile and controlled base catalyzed thiol–ene click chemistry toward electron‐deficient ?CH?CF? double bonds in poly(vinylidene fluoride) PVDF (P(VDF‐DB)) is reported in present contribution for the first time. The addition reaction is carefully conducted under varied conditions including at the elevated temperature, in the different solvents, and with the altered catalysts and thiols. The addition reaction is well confirmed to follow the base catalyzed route and exhibits close dependence onto the reaction conditions. Besides the addition reaction, the other two side reactions catalyzed by alkylamines, including the further main chain degradation of P(VDF‐DB) substrates together with the nucleophilic substitution of thiols to ?CH?CF? units, can be completely avoided by choosing a catalyst with a proper pK_a value. With respect to the universality and well controlled feature of the reaction, the low cost and readily prepared P(VDF‐DB) substrate and the mild reaction conditions, this strategy may offer a robust tool for attaching various functional groups into PVDF side chain.     

Improved Electrical Performance of Poly(3‐hexylthiophene) Induced by Stable Doping with Polymer Dopants

A series of brominated polystyrenes (BPSs) are readily synthesized and blended as polymer dopants with the p‐type semiconducting polymer, poly(3‐hexylthiophene) (P3HT), to improve theirelectrical performance. The obtained P3HT/BPS blend films exhibit increased carrier concentration resulting from doping of P3HT by BPS, which leads to excellent electrical performance, including enhanced hole mobility and conductivity, and the conductivity or mobility increases with the bromination degree of BPS. Compared with conventional small molecular dopants, the polymer dopant, BPS, shows not only excellent doping stability, but also good solution processibility, which makes it a promising materials for fabrication of low cost, flexible, transparent, and high performance solution processable organic electronic devices.

     

Cationic Polymer Based Gene Delivery Systems

Gene transfer to humans requires carriers for the plasmid DNA which canefficiently and safely carrythe gene into the nucleus of the desired cells. A series of chemically differentcationic polymers arecurrently being investigated for these purposes. Although many cationic polymersindeed condense DNAspontaneously, which is a requirement for gene transfer in most types of cells,the physicochemical andbiopharmaceutical behavior of the current generation of polyplexes severelylimits an efficient genetransfer in vitro and especially in vivo. This papersummarizes recent physicochemical and biologicalinformation on polyplexes and aims to provide new insights with respect to thistype of gene deliverysystem. Firstly, the chemical structure of frequently studied cationic polymersis represented. Secondly,the parameters influencing condensation of DNA by cationic polymers aredescribed. Thirdly, the surfaceproperties, solubility, aggregration behavior, degradation and dissociation ofpolyplexes are considered.The review ends by describing the in vitro and in vivo genetransfection behavior of polyplexes.     

Reversible Photo‐Mechanical Switching Behavior of Azobenzene‐Containing Semi‐Interpenetrating Network under UV and Visible Light Irradiation

Summary: Light‐induced reversible changes in elasticity of semi‐interpenetrating network (semi‐IPN) films bearing azobenzene moieties were achieved under both ultraviolet (UV) and visible light irradiation. The semi‐IPN film was prepared by a cationic copolymerization of azobenzene‐containing vinyl ethers in a linear polycarbonate (PC) film as a matrix. When the irradiation was switched on and off, the semi‐IPN film showed rapid reversible deformation with the same behavior occurring over a range of wavelengths, including both the UV and visible regions. The observed reversible deformation of the film was attributed to the decrease in the film's elasticity, which was assumed to be caused by the frequent trans‐cis cycling isomerization of azobenzene moieties taking place during the UV and visible light irradiation. This cycling makes it difficult for the azobenzene groups to aggregate, thus hindering their ability to function as pseudo‐crosslinking points.

     

Synthesis and Study of Copolymers Bearing Two Coumarin Side Groups in Monomer Unit: Toward Photoalignment of Liquid Crystals

Photodimerization of coumarin derivatives in photoactive polymers under linearly polarized UV (LPUV) light irradiation is a photochemical reaction often used to prepare the surface alignment layer that can orient liquid crystals (LCs) due to the anisotropic interfacial interactions. Herein, the synthesis of a series of novel coumarin-containing copolymers and their use for the photoalignment surface layer of LCs is reported. These copolymers have the particular feature of bearing two coumarin side groups in each monomer unit, which is designed to have a high content of the chromophores. The alignment of LCs induced by the photoalignment layers of the coumarin-containing copolymers is investigated. It is found that the photoalignment layers can effectively induce orientation of LC molecules along the direction of the UV light polarization used to prepare the surface layers, with an order parameter of around 0.5 achieved by adjusting the preparation conditions. Moreover, the electro-optical behaviors of LC cells made with the photoalignment layers are investigated, confirming the alignment of LCs without the use of rubbed surfaces. Optically inscribing the photoalignment layer for nonuniform and organized LC alignment is also demonstrated.     

荧光定量聚合酶链反应诊断结核病临床应用研究

目的探讨荧光定量聚合酶链反应（FQ-PCR）技术诊断结核病临床应用价值。方法应用FQ-PCR技术检测患者痰、外周血、体液（包括各种渗出液及脑脊液）中结核分枝杆菌DNA（TB-DNA），并与定性PCR、常规细菌学涂片法和培养法比较。结果112例结核病患者FQ-PCR、定性PCR、涂片法和培养法检测各类标本阳性率为59．82％，88．82％，25．89％，29．46％，非结核组43例FQ-PCR法阳性率是2．32％，PCR法是18．60％，FQ-PCR检测其标本TB-DNA的特异性为97．67％，敏感度为59．82％，阳性预测值为98．53％。结论FQ-PCR检测TB-DNA是一种快速简便、敏感性、特异性、可信性较高的方法，对诊断结核病具有临床意义，且适用于临床检验实验室，其含量变化对判断疗效有一定的提示作用。     

硫杂蒽酮类光引发剂的合成

合成了12种烷基、烷氧基和硝基取代的硫杂蒽酮类化合物。其中,三种烷氧基取代的硫杂蒽酮是用相转移催化法制得的。几种新的化合物,经红外光谱、质谱和元素分析等方法鉴定,确证了其结构。测定了化合物的紫外吸收光谱。结果表明,硫杂蒽酮类化合物的2-位上是斥电子基时,其最大吸收波长要向红移动;若2-位上是吸电子基时则向紫移动。     

Thermorheologic Properties of Aqueous Solutions and Gels of Tetronic 1508

The rheologic properties of aqueous solutions and gels of Tetronic 1508 were investigated as a function of polymer concentration and temperature utilizing rotational viscometry. Below the sol–gel transition temperature the polymer solutions were low in viscosity and exhibited Newtonian rheologic behavior even at concentrations of 20 and 25% (w/w). Upon sol–gel transition, the more concentrated polymer solutions underwent a dramatic four- to five-orders of magnitude increase in viscosity, resulting in the formation of a rigid gel structure. Above the sol-gel transition temperature, the gels displayed pseudoplastic and plastic rheologic properties and the viscosity of the gels remained at a relatively constant value over a wide temperature range. Eventually, the thermal energy of the system exceeded the bonding forces within the gel structure, resulting in a gel–sol transition which was marked by a dramatic decrease in the viscosity of the system. Above the gel–sol transition temperature, the system reverted to a Newtonian fluid with viscosities very similar to those found for the Tetronic 1508 solutions at temperatures below the sol–gel transition temperature. The thermodynamic implications of the gel–sol transition are discussed.