改性酚氧树脂/聚(甲基丙烯酸丁酯-co-4-乙烯基吡啶)共混物的相容-络合行为和表面表征

合成了一系列不同4-乙烯基吡啶含量的聚(甲基丙烯酸丁酯-co-4-乙烯基吡啶)(BVPy)共聚物,并对酚氧树脂(Phenoxy)的仲羟基进行了不同乙酰化程度的改性.用粘度法和激光光散射(LLS)研究了BVPy/改性Phenoxy共混物在溶液中的络合行为对氢键相互作用基团密度的依赖性,并用DSC研究了共混体系在本体中的相容性.将粘度法及LLS的结果结合起来,得到了改性Phenoxy/BVPy共混体系的不相容-相容-络合转变相图.在此基础上,用XPS初步考察了共混物的相容性对其表面组成的影响.结果表明,大分子间的络合相互作用可抑制共混物的表面富集.     

SAN共聚物组成对PVC/ABS共混物相容性的影响

采用乳液聚合技术通过改变共聚单体的投料比(St/AN)合成了一系列不同AN结合量的ABS接枝共聚物粉料和SAN共聚物.将其与聚氯乙烯(PVC)和邻苯二甲酸二辛酯(DOP)熔融共混分别制得了PVC/ABS、PVC/SAN、PVC/ABS/DOP和PVC/SAN/DOP共混物,利用SEM、TEM和动态力学粘弹谱仪(DMA)对共混物的相容性和相结构进行了表征.结果发现,在PVC/ABS共混体系中,尽管改变接枝SAN共聚物的AN结合量,PVC和SAN共聚物均为不相容体系;在该共混物中引入增塑剂DOP后,虽然当SAN共聚物AN结合量小于23.4 wt%时,共混物在室温以上只存在一个tanδ峰,但形态结构研究结果表明共混物仍为不相容体系,共混物的相区尺寸明显地依赖于SAN共聚物中的AN结合量,当AN结合量为23.4 wt%时相区尺寸最小.     

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(4-乙烯基吡啶)-b-聚环氧乙烷-b-聚(4-乙烯基吡啶)的合成及其用于毛细管电泳分离碱性蛋白质

用原子转移自由基聚合(ATRP)法合成了结构可控的三嵌段共聚物聚(4-乙烯基吡啶)-b-聚环氧乙烷-b-聚(4-乙烯基吡啶)(P4VP-b-PEO-b-P4VP).用核磁共振氢谱和凝胶渗透色谱对该共聚物进行了表征;将该共聚物作为毛细管物理吸附涂层,用毛细管电泳对碱性混合蛋白质进行了分离.结果表明:蛋白质的分离效率随着P...     

PI-b-P2VP两嵌段共聚物环状形貌的影响因素研究

基于最近Chang等在嵌段共聚物聚异戊二烯-聚2-乙烯基吡啶(PI-b-P2VP)的四氢呋喃-乙醇共混溶剂体系制备环状胶束的工作(Angew. Chem. 2009, 48, 4594), 我们在此基础上, 用原子力显微镜对该体系形成环状结构的影响因素包括嵌段共聚物浓度、混合溶剂配比、溶剂选择性、溶剂挥发速度、溶剂滴加顺序及选择性溶剂的滴加速度等进行了详细研究, 发现P2VP的选择性溶剂的引入是形成环状结构的关键因素. 利用P2VP与氯金酸的络合, 分析环状结构, 并进一步结合动、静态光散射及冷冻透射电镜对此形貌的形成机理进行探究.     

4-乙烯基吡啶与丙烯酰胺共聚合的研究

以过硫酸钾为引发剂 ,采用溶液自由基共聚合方法 ,实现了丙烯酰胺 (AM)与 4 乙烯基吡啶 (4 VP)的共聚合 .通过详细研究共溶剂体系、单体总浓度、反应温度、反应时间及引发剂量对共聚合过程中转化率和分子量的影响 ,从而确定了适宜的共溶剂体系和最佳的工艺条件 .用紫外分光光度法测得了共聚物的组成 .用Kelen Tudos方法 ,求得 4 乙烯基吡啶 (4 VP)和丙烯酰胺 (AM)单体的竞聚率 ,r4 VP =0 6 4 4 ,rAM =0 371.最后通过FTIR和1 3C NMR表征共聚物的结构并验证了共聚物的组成 .     

离子自组装合成侧链型偶氮复合物及其聚集形态研究

用溶液聚合法制备了4-乙烯基吡啶与丙烯腈的无规共聚物(P4VP-r-AN), 采用¹H NMR, ¹³C NMR, DSC和FTIR等手段确定了其结构和组成. 粘度法测得其粘均分子量为1.06×10⁴ g/mol, 由其¹H NMR 谱峰面积估算得到4-乙烯基吡啶链段的质量百分含量约为87.1%. 以质子化的4-乙烯基吡啶-丙烯腈无规共聚物(P4VP^＋-r-AN)为模板, 与酸性间胺黄(MY)在水溶液中通过离子自组装, 制备了一种侧链型偶氮复合物(P4VP-r-AN/MY). 用¹H NMR, FT-IR, DSC, UV-Vis, SEM, TEM和HRTEM&EDS(高分辨率透射电镜与X射线能谱联用)等手段研究了该复合物的聚集形态及自组装过程. 研究发现MY通过静电相互作用复合到P4VP^＋-r-AN链上并发生聚集, 使复合物分子链聚集形成尺寸为10～200 nm的球形聚集体. P4VP-r-AN/MY中, MY与P4VP-r-AN的物质的量之比为0.575. HRTEM&EDS测试结果显示P4VP-AN/MY球形聚集体中硫元素的分布接近球形, 与聚集体的形状几乎一致, 表明MY分子在该组装物中主要以球形纳米聚集体的形式存在.     

离聚物及其共混体系的研究3.基于配位络合的增容作用

通过将苯乙烯(S)与少量的甲基丙烯酸(MAA)或马来酸酐(MA)共聚及甲基丙烯酸正丁酯(nBMA)与4-乙烯基吡啶(4-VP)共聚,从而在聚苯乙烯(PS)及聚甲基丙烯酸丁酯(PBMA)链上分别引入了功能基团羧酸基(-CO-OH)、酸酐基(-CO-O-CO-)和吡啶基(-N)。通过与锌盐作用获得相应的离聚物(Ionomer)。用红外光谱(IR)表征了共聚物和离聚物的形成;差热分析(DSC)测定共聚物、离聚物和共混物的玻璃化转变温度(Tg)。研究结果表明,随着共聚物中功能基团含量的增加或者共聚物形成离聚物后,其玻璃化转变温度(Tg)提高了;而共聚物的共混物因羧酸基与吡啶基间的质子转移作用而提高了相容性。特别是在引入Zn~(2+)的共混物中,增容作用十分明显,这可归结于BMAVP中的吡啶基和SMAA-Zn~(2+)(或SMA-Zn~(2+))中的Zn~(2+)间的配位络合作用的贡献。     

反相气相色谱法研究聚合物共混物的相溶性

 用反相气相色谱法测定了聚氯乙烯(PVC)／ 乙烯-醋酸乙烯共聚物(EVA)共混体系中分子间表观热力学相互作用参数χ′23,并以χ′23 为判定依据,研究了共混物的相溶性。 初步探讨了共混物的组成、聚合物分子 链结 构、温度与χ′23的关系以及探针分子性质 对χ′23参数的影响。结果表明：χ[ HT6〗′23值能够准确有效地判定PVC与EVA共混物的 相溶性,醋酸乙烯质量分数低的EVA与PVC的共混物是热力学不相溶的;而醋酸乙烯质量 分数中等的EVA与PVC的共混物则具有部分相溶性。结果与其它方法得到的结论是一致的 。     

聚环氧乙烷与聚2-乙烯基吡啶混物的导电率及高氯酸锂的增容作用

研究了聚环氧乙烷(PEO)/聚2-乙烯基吡啶(P2VP)的共混物分别经LiCLO₄、四氰基代苯醌二甲烷(TCNQ)及两者共同掺杂后其共混物的离子、电子及混合导电率。当PEO与P2VP的重量比分别为6/4、5/5及4/6时,共混物的混合导电率大于相应的离子及电子导电率的总和,呈现协同效应。从共混物外观的研究发现LiCLO₄能作为PEO/P2VP共混体系的增容剂。     

Antibacterial activities of polystyrene-block-poly(4-vinyl pyridine) and poly(styrene-random-4-vinyl pyridine)

Styrene was polymerized in the presence of benzoyl peroxide (BPO) and 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) to yield polystyrene-TEMPO (PS-TEMPO) macroinitiator. The PS-TEMPO macroinitiator with different molecular weight was reacted with 4-vinyl pyridine (4-VP) to synthesize polystyrene-block-poly(4-vinyl pyridine) (PS-b-PVP), which was then quaternized with n-octyl iodide. Antibacterial activity of the quaternized copolymers was assessed against a gram negative bacterium (Pseudomonas aeruginosa) and a gram positive one (Staphylococcus aureus) by using the shake flask test method, and the results were compared with those of poly(styrene-random-4-vinyl pyridine) (P(ST-r--VP)). The quaternized copolymers inhibited greatly the growth of the bacteria, and PS-b-PVP was more active than P(ST-r-VP), which was ascribed to the fact that the content of quaternized 4-VP units on the surface of the particles of the former copolymer was higher than that corresponding to the latter one.     

Antibacterial behaviour of quaternized poly(vinyl chloride)-g-poly(4-vinyl pyridine) graft copolymers

Amphiphilic graft copolymers consisting of poly(vinyl chloride)(PVC) main chains and poly(4-vinyl pyridine)(P4VP) side chains were synthesized via atom transfer radical polymerization(ATRP) using direct initiation of chlorine atoms. The successful synthesis of PVC-g-P4 VP graft copolymers was confirmed by Fourier transform infrared spectroscopy(FTIR) and proton nuclear magnetic resonance(1H-NMR). Transmission electron microscope(TEM) and small angle X-ray scattering(SAXS) analysis showed that PVC-g-P4 VP exhibited microphase-separated, ordered structure with 37.6 nm of domain spacing, which was not observed in neat PVC. For antibacterial applications, the tertiary nitrogen atoms of PVC-gP4 VP was quaternized using 1-bromohexane, as confirmed by FTIR measurements. Bacteria including Escherichia coli(E. coli), Staphylococcus aureus(S. aureus), Bacillus cereus(B. cereus), and Pseudomonas aeruginosa(P. aeruginosa) were completely killed in 24 h on the quaternized PVC-g-P4VP(46% grafting) surface, indicating its excellent antibacterial behavior while it showed to be cytotoxic to mammalian cell.     

Thermal and dilute-solution properties of zwitterionic copolymers

We report the synthesis, characterization, thermal and dilute-solution properties of zwitterionic copolymers of the sulfobetaine type, where the proportion of ionic groups is varied over a wide range. Two different structures are considered: poly (2-vinyl pyridine sulfopropyl betaine) and poly (4-vinyl pyridine sulfopropyl betaine). Synthesis is carried out to obtain random copolymers which are further characterized and their ionic content determined. At low proportions of ionic groups, the behavior is similar to that observed in ionomers, with substantial differences between the two structures, Increased interaction among the zwitterionic groups at higher charge densities is evidenced, which leads to the formation of clusters and agglomerates. An increase in the intrinsic viscosity with salt content in aqueous solutions is also observed. This behavior is analogous to that of homopolymers with 100% ionic content, but with particular features of interest.     

Molecular weight control in polycondensation of hydroxyl diesters with hexamethylenediamine by polymer matrices

Polycondensation reactions of hydroxyl diesters such as dimethyl tartrate (DMT) and diethyl mucate (DEM) with hexamethylenediamine (HMD) were carried out in the presence of poly(vinyl pyridine) (P-VPy) and its copolymers with styrene of different compositions as matrix polymers in order to investigate the difference in interaction forces with monomers or the resulting polyamides owing to hydrogen bonding. It was found that matrix effects of poly(4-vinyl pyridine) (P-4VPy) on the rate enhancement and solution viscosity of the resulting polyamide became more pronounced with decreasing solvent polarity. This result suggests that the matrix effects of P-4VPy on polycondensation are due to hydrogen bonding interactions between hydroxyl diesters and P-4VPy. The addition of P-4VPy increased the molecular weight of the resulting polyamide to a higher extent than poly(2-vinyl pyridine) (P-2VPy), and the molecular weight of the resulting polyamide could be controlled according to the molecular weight of P-4VPy. Copolymer composition of 4-vinyl pyridine–styrene (4VPy/St) copolymers as matrix polymers also affected the molecular weight of the polyamide, which increased with increasing P-4VPy unit contents in the copolymers.     

Study of the miscibility of poly(vinyl pyridines) with poly(vinyl acetate), poly(vinyl alcohol) and their copolymers

Miscibility of poly(4-vinyl pyridine) (P4VP) and poly(2-vinyl pyridine) (P2VP) with poly(viny acetate) (PVAc), poly(vinyl alcohol) PVA and poly(vinyl acetate-co-alcohol) (ACA copolymers) has been investigated over a wide composition range. Differentiaal scanning calorimetry (DSC) results indicate that P2VP is immiscible with PVAC, PVA, and their copolymers over the whole composition range. In turn, P4VP appears to be immiscible with PVAC and PVA, but miscible with some ACA copolymers in certain range of composition. The P4VP-ACA phase diagram for different copolymer compositions has been determined. The variation of the glass transition temperature with composition for miscible mixtures was found to follow the Gordon-Taylor equation, with the parameter κ dependent upon copolymer composition. FTIR analysis of blends reveal the existence of specific interactions via hydrogen bonding between hydroxyl groups and the nitrogen of the pyridinic ring, which appear to be decisive for miscibility. © 1994 John Wiley & Sons, Inc.     

Preparation of stable gold nanoparticles by using diblock copolymer mixture as encapsulating agent

Gold nanoparticles by using the mixture of polystyrene-block-poly(2-vinyl pyridine)/poly(2-vinyl pyridine)-block-poly(ethylene oxide) (PS-b-P2VP/P2VP-b-PEO) block copolymers as encapsulating agent was prepared. The prepared nanoparticles were characterized by transmission electron microscopy, UV-Vis spectroscopy and contact angle. It is demonstrated that the obtained gold nanoparticles are covered with mixed block copolymer shells. The hydrophilic property of the nanoparticles can be varied by the change of the dispersion medium. The obtained gold nanoparticles with mixed block copolymer shells are stable in organic solvents (such as tetrahydrofuran and toluene) and water.     

Poly(oxyethylene methacrylate)–poly(4-vinyl pyridine) comb-like polymer electrolytes for solid-state dye-sensitized solar cells

Poly(oxyethylene methacrylate)–poly(4-vinyl pyridine) (POEM–P4VP) comb-like copolymers with 3:7, 5:5, and 6:4 wt ratio were synthesized via atom transfer radical polymerization and confirmed by ¹H-NMR and FT-IR spectroscopy. The copolymers were quaternized with 1-iodopropane to convert the pyridine groups into pyridinium ions, i.e., POEM–qP4VP. Transmission electron microscopy showed that strongly segregated microphase separation in POEM–P4VP was less prominent upon quaternization due to interactions between the ether oxygens of POEM and the quaternized pyridine groups of qP4VP, as confirmed by FT-IR spectroscopy. The energy conversion efficiencies of dye-sensitized solar cells (DSSCs) with quaternized polymer electrolytes were always greater than those with pristine electrolytes due to greater ionic conductivity and concentrations of free iodide ions. The maximum energy conversion efficiency of a DSSC employing POEM–qP4VP electrolyte reached 3.0% at 100 mW/cm² when a 6:4 wt.% of POEM–qP4VP was used.     

Formation and catalytic activity of spherical composites with surfaces coated with gold nanoparticles

Micelle-supported gold composites with a polystyrene core and a poly(4-vinyl pyridine)/Au shell are synthesized using NaBH(4) to reduce a mixture of micelle and HAuCl(4) in acidic aqueous solution (pH approximately 2). The template micelle with a polystyrene core and a poly(4-vinyl pyridine) shell is formed by self-assembly of block copolymer polystyrene-block-poly(4-vinyl pyridine). The gold nanoparticles coated onto the surfaces of the composites possess an average diameter of about 15 nm. The composites are applied to catalyze the reduction of p-nitrophenol in the presence of NaBH(4), and the results indicate that the kinetic constant of the reaction increases when the composite concentration and the reaction temperature increase. In addition, research results also indicate that composites with high content of gold show higher catalytic activity and higher catalytic efficiency.