含pH敏感聚(4-乙烯基吡啶)的嵌段共聚物成核胶束化过程的NMR研究

利用NMR技术研究了聚乙二醇-b-聚(4-乙烯基吡啶)(PEG114-b-P4VP107)和聚(N-异丙烯基丙烯酰胺)-b-聚(4-乙烯基吡啶)(PNIPAM53-b-P4VP260)在逐步降低聚(4-乙烯基吡啶)链段质子化程度时嵌段共聚物的胶束化过程.在开始形成胶束时,吡啶环上氢原子的自旋-晶格弛豫时间(T1)急剧减小.结果表明,PEG114-b-P4VP107在质子化程度降为0.54时已有胶束生成;PNIPAM53-b-P4VP260在质子化程度降为0.58时也能观测到胶束生成的信号.将两个嵌段共聚物各自制得胶束的溶液相混合,观测到了发生在高分子链间的2DNOE信号,这表明所制得溶液中胶束与高分子链间有链交换的动态平衡.     

聚(丙烯酸钠-4-乙烯基吡啶)的生物降解性和功能性研究

用自由基共聚法制备了一系列可生物降解的功能聚合物聚(丙烯酸钠-4-乙烯基吡啶)[P(SA-co-4VP)],研究了其组成和分子量与生物降解性、资合性及分散性间的关系.结果表明:聚合物中小乙烯基吡啶含量越大,P(SA-co-4VP)的生物降解越显著.分子是一定时,少量的个乙烯基吡啶引入聚丙烯酸钠主链是增强聚合物生物降解性和保持原有功能特性的有效途径.     

聚（异丙基丙烯酰胺）-b-聚（4-乙烯基吡啶）胶束负载铂纳米粒子的温度响应性催化

嵌段共聚物聚(N-异丙基丙烯酰胺)-b-聚(4-乙烯基吡啶)(PNPIAM-b-P4VP)在pH6.5的水溶液中自组装成,以聚(4-乙烯基吡啶)为胶束的核,以热响应聚(N-异丙基丙烯酰胺)为胶束壳的球形胶束.通过与4VP基络合作用,将氯铂酸(H2PtCl6)导入胶束的核中,原位还原获得胶束负载2~4nm的铂纳米粒子的温度敏感型催化体系.结果显示,最低临界溶解温度(LCST)为33℃,在LCST以下,催化反应速率会随着温度的升高而提高;在LCST以上,PNPIAM嵌段变成疏水而塌缩在催化剂表面,阻碍了反应物的扩散,因此胶束负载的铂纳米粒子的催化活性会随着温度的上升而下降.     

聚(4-乙烯基吡啶)诱导一步法合成纺锤形钨酸钡晶体

利用高分子量的含氮杂环聚合物聚(4-乙烯基吡啶)(P4VP)作为模板合成了纺锤形钨酸钡晶体,为制备形貌可控的钨酸钡晶体提供了一种简单、条件温和、容易控制的方法.用扫描电镜、透射电镜及X-射线衍射等手段研究了钨酸钡晶体的晶型及形貌.并讨论了P4VP的浓度、溶液离子浓度、pH值等因素对钨酸钡晶体形貌的影响.     

光敏感遥爪聚合物——聚4-乙烯基吡啶的制备及其溶液性质

以香豆素二硫化物(C-S-S-C)/三丁基膦(Bu₃P)/H₂O复合体系为链转移剂, 偶氮二异丁腈(AIBN)为引发剂, 4-乙烯基吡啶为单体制备了末端含有疏水性香豆素光响应基元的光敏感遥爪聚合物(聚4-乙烯基吡啶(C-P4VP)). 用傅里叶变换红外(FTIR)光谱、凝胶渗透色谱(GPC)、氢核磁共振(¹H-NMR)等对该聚合物进行了结构表征. 研究显示该遥爪聚合物可在不同pH值(pH=3-6)的酸性水溶液中自组装成胶束, 且随体系酸值的降低, 聚合物胶束结构由松散变为紧密, 同时香豆素端基的光二聚反应程度呈现先下降后上升的趋势.     

模板法制备聚苯乙烯/聚4-乙烯基吡啶功能微球

以工业化的聚苯乙烯中空微球为模板,利用种子乳液法合成了粒径均一的功能化中空聚苯乙烯/聚4-乙烯基吡啶(PS/P4VP)微球,改变制备条件可以控制功能基团4-乙烯基吡啶(4-VP)在聚苯乙烯微球表面的分布.合成的微球在水和有机溶剂如二氯甲烷、乙醇、乙腈等中有良好的分散性,并能促进油水体系混溶.     

聚(4-乙烯基吡啶季铵盐-丙烯酰胺)的抗菌性能与机理研究

季铵盐型阳离子聚合物具有絮凝、缓蚀与杀菌等多种功能,据此,我们通过分子设计,先将丙烯酰胺与4-乙烯基吡啶（4-VP）进行共聚合,然后使用季铵化试剂硫酸二甲酯使共聚物阳离子化,制备了吡啶季铵盐型阳离子聚丙烯酰胺（QPAV）,本文报道QPAV的抗菌性能,并探讨其抗菌机理,结果表明,吡啶季铵盐型阳离子聚丙烯酰胺具有很强的抗菌性能,且其抗菌机理是基于杀菌而不仅仅是抑菌。     

芳基碘化物[聚(4-乙烯基吡啶)]钯(0)催化下的乙烯基化反应

前文报道了聚[(苯乙烯)联吡啶]钯(0)催化剂在芳基碘化物乙烯基化反应中的应用,其催化剂的活性较高,但连续使用三次后,活性明显降低.本文继续报道能用于芳基碘化物乙烯基化反应的高分子负载钯催化剂的合成和应用.据文献报道能用于芳基碘化物乙烯基化的高分子负载钯催化剂,都是通过多步反应将配体导入聚苯乙烯骨架上合成的,操作比较复杂.为了简化催化剂的制备方法,我们探索了用聚(4-乙烯基吡啶)作高分子载体的可能性.将4 乙烯基吡啶与苯乙烯共聚,加入2%二乙烯基苯作交联剂,生成的共聚物用醋酸钯处理后,加氢化铝锂还原,得到每克含钯7.0mg、氮33.7mg的催化剂,并研究了它在芳基碘化物与苯乙烯、丙烯酸和丙烯酰胺的反应中的催化性能.     

丙烯酰胺与4-乙烯基吡啶共聚合反应竞聚率

测定了丙烯酰胺与4－乙烯基吡啶共聚反应的竞聚率。用紫外分光光度法测定了不同浓度的4－乙烯基吡啶均聚物的吸光度，从而求出在低转化率不同初始单体组成的共聚物中4－乙烯基吡啶含量。用FR和KT两种作图法及YBR计算法对单体的竞聚率进行计算和比较。结果表明：KT法和YBR法计算法较为准确，4－乙烯基吡啶的竞聚率和丙烯酰胺的竞聚率分别为γrVP=0.636,γAM=0.379。     

聚偏氟乙烯/聚4-乙烯基吡啶Janus粒子的制备

用聚偏氟乙烯(PVDF)乳胶粒子作为种子,4-乙烯基吡啶(4VP)作为功能性单体,通过无皂种子乳液聚合的方法,制备了具有雪人形结构的不对称复合粒子,重点考察了氨水加入量对产物粒子形态的影响.采用动态光散射法测定了复合粒子的平均粒径及粒径分布,利用扫描电镜表征了复合粒子的微观形貌,通过红外光谱分析验证了复合粒子的化学组成,借助示差扫描量热仪研究了复合粒子中PVDF的结晶行为.在该体系中,引入适量的氨水对于控制体系的稳定性以及生成的复合粒子结构的均匀性起到了至关重要的作用,这是由于氨水的加入抑制了4-乙烯基吡啶在水相聚合时的成核和凝聚.最终获得了一端为PVDF半球,另一端为带有吡啶基团的P4VP雪人形粒子,其具备反应活性位点.     

Supramolecular Complex of Poly(styrene)-b-Poly(4-vinylpyridine) and 1-Pyrenebutyric Acid in Thin Film

Summary: Here, we have described a novel supramolecular complex (SMC) between poly(styrene)-b-poly(4-vinylpyridine) (PS-b-P4VP) and 1-pyrenebutyric acid (PBA) and studied of its self assembly in thin film. PBA will make supramolecular complex with the P4VP block due to strong hydrogen bonding between the carboxylic group of 1-pyrenebutyric acid and pyridine ring of P4VP. The formation of supramolecular complex between PS-P4VP and PBA through hydrogen bonding is investigated through FTIR study. The supramolecular complex of PS-b-P4VP and 1-pyrenebutyric acid changed the block copolymer morphology from cylindrical to lamella in thin film due to the increase of the volume fraction of P4VP (PBA). In both cases (parent block copolymer and SMC), the microdomains are oriented normal to the substrate after annealing in a selective solvent. Pure block copolymer shows cylindrical morphology with a periodicity of ∼26 nm, whereas the SMC shows lamellar morphology with a periodicity of ∼ 29 nm. After fabricating the thin film from SMC, 1-pyrenebutyric acid can be easily removed by dissolving the thin film in ethanol to transform the block copolymer thin film into nanotemplate or membrane.     

Stereoregularity of poly(2-vinylpyridine) and poly-(4-vinylpyridine)

In order to determine the stereoregularity of poly(4-vinylpyridine), 4-vinylpyridine-β,β-d₂ was synthesized from 4-acetylpyridine. The ¹H-NMR spectra of the deuterated and nondeuterated polymers were measured and analyzed. From the ¹H-NMR spectra of poly(4-vinylpyridine-β,β-d₂), triad tacticity can be obtained, while the ¹H-NMR spectra of nondeuterated poly(4-vinylpyridine) give the fraction of isotactic triad. The ¹³C-NMR spectra of poly(4-vinylpyridine) were also observed, and the spectra of C₄ carbon of polymers were assigned by the pentad tacticities. The fraction of isotactic triad of poly(2-vinylpyridine) and poly(4-vinylpyridine) obtained under various polymerization conditions were determined. The radical polymerization and anionic polymerizations with phenylmagnesium bromide and n-butyllithium as catalysts of 4-vinylpyridine gave atactic polymers.     

Polyoxometalate-modulated self-assembly of polystyrene-block-poly(4-vinylpyridine)

Polyoxometalates can serve as active components to induce and modulate the micellization behavior of polystyrene-block-poly(4-vinylpyridine).     

Fabrication of Poly（4-vinylpyridine） Nanofiber and Fluorescent Poly（4-vinylpyridine）/Porphyrin Nanofiber by Electrospinning

Poly（4-vinylpyridine）（P4-VP） nanofiber and fluoresent poly（4-vinylpyridine）/porphyrin（P4-VP/TPPA） nanofiber were respectively prepared by electrospinning. The effect of the concentration of P4-VP/dimethylformamide （DMF） electrospinning solutions on the morphology of P4-VP nanofiber was investigated and it was found that the average diameter of the nanofiber of P4-VP/DMF increased with the increase of the concentration of the spinning solution. After the addition of TPPA to the P4-VP/DMF spinning solution, the diameter of P4-VP/TPPA nanofiber became even due to the increase of the conductivity of the P4-VP/DMF-TPPA solution. The photoluminescent（PL） spectral analysis indicates that the emission peak position of P4-VP/TPPA nanofiber is almost the same as that of pure TPPA at about 650 nm without peak shift, and when it was stored for 20 days, the emission peak of P4-VP/TPPA nanofiber is also at 650 nm, indicating that the fluorescent property of P4-VP/TPPA nanofiber is stable. Fourier-transform iufrared（FTIR） spectrum confirms the chemical composition of the resulting P4-VP/TPPA composite nanofiber.     

Incorporation of Dyes into Polystyrene-block-poly(4-vinylpyridine) Nanotemplates

Summary: The present study provides some basic concepts of functionalization of diblock copolymer (BC) nanotemplates for optical applications. It is focused on the polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) building medium which is suitable for hydrogen bonding, undergoes phase segregation, and is well-accessible. Two techniques are described and demonstrated on several dye complexes with PS-b-P4VP. Relation between optical properties and thin film structure is tentatively studied in dependence on solvent effects in thin films.     

Miscibility of poly(butyl methacrylate-CO-methacrylic acid) or poly(styrene-CO-methacrylic acid) with poly(styrene-CO-4-vinylpyridine) or poly(butyl methacrylate-CO-4-vinylpyridine)

The miscibility of blends of copolymers of different compositions of butyl methacrylate-co-methacrylic acid or styrene-co-methacrylic acid with styrene-co-4-vinylpyridine or butyl methacrylate-co-4-vinylpyridine was studied by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. It was found that these blends were miscible in part as a result of specific favorable interactions between the carboxylic acid and pyridine groups within the polymer chains. Evidence of such interactions was obtained from the single composition-dependent glass transition temperature and the FTIR results.     

Thermal degradation and stability of poly(4-vinylpyridine) homopolymer and copolymers of 4-vinylpyridine with methyl acrylate

The thermal stability and degradation behaviour of poly(4-vinylpyridine) (PVP) homopolymer and copolymers of 4-vinylpyridine and methyl acrylate (VP-MA) have been investigated. The reactivity ratios in the copolymerization were determined using an NMR method. The apparent activation energies of the degradation of the homopolymers and copolymers were calculated using the Arrhenius equation.