含硅十六元大环线性环化聚合物的控制合成及表征

利用硅上的thorpe-ingold效应,设计并合成了非共轭的双甲基丙烯酸酯类的单体,通过原子转移自由基聚合(ATRP)方法控制合成了含十六元大环的线性环化聚合物,对所合成聚合物的结构进行了1H NMR、13C NMR和GPC的表征.

可控活性聚合多乙烯基单体制备新型单链超内环化聚合物的研究历史及进展

多乙烯基单体因其方便易得、固有的反应多活性位点而一直是合成多种复杂拓扑结构聚合物的理想单体;然而Flory-Stockmayer(F-S)均相场理论及广泛的前期尝试已证实多乙烯基单体的聚合会在极低转化率(<10%)下形成凝胶,而无法进行可控聚合.近年来,可控活性聚合方法的发展为动力学控制下的多乙烯基单体聚合奠定了基础,并成功合成多种具有不同复杂结构的聚合物.特别地,合成了具有新颖拓扑结构的单链超内环化聚合物.本文综述了近年来多乙烯基单体聚合的历史,动力学控制下的可控活性聚合机理以及单链超内环化聚合物的聚合过程、结构特征、应用等,展望了该新颖结构聚合物的应用前景,并对多乙烯基单体的可控活性聚合领域的未来发展提出了建议.

ATRP法合成二十元、二十八元线形环化聚合物

采用以甲苯为聚合介质的ATRP聚合体系,以双甲基丙烯酸二醇酯为单体,合成了具有二十和二十八元环的线形环化聚合物,聚合物具有窄分子量分布.聚合动力学显示随着链长的增加,环化反应速率变慢.根据聚合物的1H-NMR谱图、由1H-NMR端基分析得到聚合度DPNMR、以及GPC图谱结果,证实获得了线形环化聚合物.TGA测试结果表明2种聚合物的起始分解温度均大于372℃,具有比PMMA更好的热稳定性.

α,ω-双烯烃的配位聚合:催化剂对聚合物微观结构的调控

在聚烯烃行业蓬勃发展的几十年中,如何合成具有独特结构和功能的聚烯烃一直是高分子化学家不断追求的目标.时至今日,科学家们已经可以通过调控单体结构、催化剂中心金属、配体结构以及聚合条件等来合成丰富多彩的聚烯烃.在这品类繁多的聚烯烃中,主链上含有脂肪环的聚烯烃因具有良好的热稳定性和透明度受到了广泛的关注.α,ω-双烯烃的配位聚合是获得主链含脂肪环的聚合物的一种高效手段,这种方法具有单体易得且易修饰、聚合物微观结构可以被催化剂高效调控等优点.根据第一次插入反应后的中间体发生的不同双键的插入反应可得到交联、含悬挂双键或含脂肪环的聚合物.根据所得环化聚合物的环内两根支链的相对朝向将其分为顺反立构体;再通过环与环之间的相对构型分为等规或间规立构体;根据催化剂与单体发生第一次插入反应的1,2-插入或2,1-插入方式可以得到结构单元为单亚甲基环或二亚甲基环的聚合物;根据催化剂的绝对构型不同可以得到旋光度大小一致、方向相反的手性聚合物.上述这些聚合物的微观结构对于其聚集状态、热力学以及机械力学性能等可能会有明显的影响,而这些均可以通过改变催化剂的中心金属和配体结构来进行精细的调控.这篇综述着眼于α,ω-双烯烃的聚合物的精细结构,着重介绍了如何通过变换催化剂结构来调控聚合物的结构,并对该领域未来可能的发展方向进行了预测,从而推动该类聚合物在构效关系、实际应用等方面的长足发展.

Disiloxane-Bridged Cyclopolymer as Polymer Dielectrics

We studied the dielectric properties of organosilicon-containing helical cyclopolymer PbMA which consists of PMMA main chains and tetramethyldisiloxane side rings. PbMA formed films with excellent uniformity through spin-coating onto highly n-doped silicon （n-Si） wafers for constructing devices of dielectric measurements, on which the dielectric properties and I-V characteristics of PbMA were studied. PbMA has a much lower dielectric constant （lower than 2.6） in the frequency range of 10-105 Hz, and better thermal stability than PMMA does. I-V data showed that the metal/PbMA/n-Si devices have different conducting directions, depending on whether Au or Al deposited over PbMA layers.

SYNTHESIS OF A NOVEL CHELATING RESIN WITH HETEROCYCLIC RING OF S AND N

By the reaction of poly(bromoacetyl styrene) (EBPS) with thiaurea (TU), a kind of novel chelating resin with heterocyaclic ring of sulfur and nitrogen, poly[4-(2-amino)thiazoleyl-4- vinylbenzene], was synthesized. Its structure was characterized by FTIR and elemental analysis. The factors which have influence on the reaction such as reaction time, solvents, and molar ratio of reactants were investigated.

Immobilization of β-Cyclodextrin as Insoluble β-Cyclodextrin Polymer and Its Catalytic Performance

Insoluble β-cyclodextrin polymers were prepared from β-cyclodextrin(β-CD) using epichlorohydrin(EPI) as crosslinking agent under basic conditions.The polymers were characterized by Fourier Transform Infrared(FTIR),Thermogravimetry(TG),X-ray diffraction(XRD) and TG-FTIR.The results demonstrated that the polym-erization between EPI and β-CD indeed occurred,and a number of CD rings were interconnected to form a three-dimensional network.Moreover,different factors influencing the polymerization,e.g.molar ratio of EPI to β-CD,the concentration of NaOH and reaction temperature,have been investigated.The polymer prepared under the optimal conditions(the molar ratio EPI:β-CD of 44,the NaOH concentration 50% in mass,and the temperature at 65 ℃) showed excellent thermal stability and insolubility in organic solvents or strong acid/base.In addition,the β-cyclodextrin polymers also presented high catalytic activity for aqueous oxidation of benzyl alcohol with hy-pochlorite as oxidant.

Influence of surfactant concentration on counter-ion induced solubility of poly(pyridine-2,5-diyl)

Protonating the pyridine rings of poly(pyridine-2,5-diyl) with dodecybenzenesulfonic acid and camphorsulphonic acid produces polymer materials which can be dissolved in chloroform (in contrast to the unprotonated polymer, which can only be dissolved in strong acids such as formic acid) and allows mixing the protonated polymers with other chloroform soluble conju- gated polymers for use in electronic devices. The protonating behavior of poly(pyridine-2,5-diyl) with two kinds of surfactants is different in some levels. Dodecybenzenesulfonic acid has higher protonating ability than camphorsulphonic acid.

Biphenyl Bis [π-cyclopentadienyl ） iron] Dication as an Efficient Cationic Photoinitiator for Epoxy Polymerization

Ferrocenium monocations as photoinitiators for cationic photopolymerization suffer from a limitation of low absorption and low reactivity under high-pressure Hg lamp. Here, a ferrocenium dication salt, biphenyl bis [π-cyclopentadienyl）iron] hexafluorophosphate （[bis（Cp-Fe）-biphenyl] （PF6）2 was synthesized by the ligand exchange reaction between ferrocene and biphenyl. The chemical structure was characterized with FTIR and ^1HNMR. The separation of ferrocenium monocation cyclopentadien-iron-biphenyl hexafluorophosphate （[Cp-Fe-biphenyl] PF6） and dication [bis（Cp-Fe）-biphenyl] （PF6）2 was carried out by column chromatography. The photoactivity of initiating photopolyinerization of epoxide ER14221 was studied as a cationic photoinitiator. [Bis（Cp-Fe）-biphenyl] （PF6）2 can efficiently absorb radiation above 300nm and its photoactivity is higher than that of its monocation.

Characteristics of Cyanate Ester and Fluorenyl Epoxy-Based Polymer-Ceramic Composites

In the field of highly integrated printed circuit board （PCB）, the heat resistant substrate with low water absorption is very important material. To get the resin composition for the high functional substrate material with low moisture absorption and high glass transition temperature （Tg） simultaneously, a fluorenyl ＂Cardo＂ epoxy was incorporated into novolac cyanate ester resin. As an optimum curing agent for the fiuorenyl epoxy, methyl nadic anhydride （MNA） was selected. Silica powders as fillers were added into the resin composition. The partial replacement of the cyanate ester resin with the fluorenyl epoxy could reduce the moisture absorption with keeping high glass transition temperature over 300 ℃. The laminate, which was fabricated from prepregs made with 40 wt% silica-filled resin composition and glass fabric, showed high Tg of 317 ℃ and low moisture absorption of 0.57%.

Recent advances in “living”/controlled radical polymerization of phosphorus-containing monomers and their potential applications

Special research attention has been paid to phosphorus-containing materials and their corresponding applications. This mini review considers recent publications devoted to the "living"/controlled radical(co)polymerization of phosphorus-containing monomers. In addition, different properties of the polymers involved in the phosphonate group in various chemical environments are demonstrated, and their potential applications are briefly discussed.

Recent advances of the Bergman cyclization in polymer science

The Bergman cyclization has strongly impacted on a number of fields including pharmaceutics, synthetic chemistry, and material science. The diradical intermediates stemmed from enediynes can not only cause DNA cleavage under physiological conditions but also function as monomer or initiator participants in polymer science. The homo-polymerization of enediynes through the Bergman cyclization to fabricate conjugated polymers is a fascinating strategy due to the advantages of facial operation, high efficiency, tailored structure, and catalyst-free operation. Moreover, conjugated polymers generated through the Bergman cyclization show many remarkable properties, such as excellent thermal stability, good solubility, and processability, which enables these polymers to be further manufactured into carbon-rich materials. Recent times have seen extensive efforts devoted to the application of the Bergman cyclization in polymer science and materials chemistry. A variety of synthetic strategies have been developed to fabricate structurally unique materials via the Bergman cyclization, including the fabrication of rod-like polymers with polyester, dendrimers and chiral imide side chains, functionalization of carbon nanomaterials by surface-grafting conjugated polymers, formation of nanoparticles by intramolecular collapse of single polymer chains, and the construction of carbon nanomembranes with different morphologies. Future developments involving the Bergman cyclization in polymer science, probably by altering the reaction mechanism to precisely control the microstructure of polymeric products, are also proposed in this review article.

Analysis of the suspension polymerization flows of polyvinyl chloride with the exergy analysis involving resource utilization and environmental influence

In order to comprehensively assess the resource utilization of aprocess system and its influence on the environment, the application range of the traditional exergy analysis was expanded in this paper to include the pollution degree of the discharged wastes to the environment. So technology indexes can be obtained to comprehensively assess the resource utilization and the environment impact of a process system. The harm coefficient and effect coefficient were introduced to concern the different harm to the environment of the different wastes and the pollution effect relative to resource waste by environment. The determination method of the harm coefficient and effect coefficient was discussed. Two suspension polymerization flows of polyvinyl chloride were calculated with this method. The results show that the method can comprehensively assess the resource utilization and the environment impact of the chemical process system by comparing and analyzing.

Controlled/living ring-opening polymerization of ε-caprolactone catalyzed by phosphoric acid

The bulk ring-opening polymerization （ROP） of ε-caprolactone （ε-CL） by various phosphoric acids using phenylmethanol as the initiator was conducted. 1, 1＇-bi-2-Naphthol （BINOL）-based phosphoric acid was found to be an effective organocatalyst for ROP leading to polyesters at 90℃. The overall conversion to poly（ε-caprolactone） was more than 96% and poly（ε-caprolactone） with Mw of 8400 and polydispersity index of 1.13 was obtained. IH NMR spectra of oligomers demonstrated the quantitative incorporation of the protic initiator in the polymer chains and showed that transesterification reactions did not occur to a significant extent. The controlled polymerization was indicated by the linear relationships between the number-average molar mass and monomer conversion or monomer-to-initiator ratio. In addition, the present protocol provided an easy-to-handle, inexpensive and environmentally benign entry for the synthesis of biodegradable materials as well as polyesters for biomedical applications.