Homopolymerization of N-pyrimidinyl acrylamide

Homopolymerization of N-pyrimidinyl acrylamide (NPA) was reported for the first time. The polymer (polyNPA) was soluble only in acidic media and fluoroalcohols, and only in fluoroalcohol was homogeneous polymerization of NPA feasible. 1H NMR analysis proved that a 1:1 H-bonding complex could be formed between NPA and α,α-bis(trifluoromethyl)phenyl propan-2-ol (BTMP). Cumyl dithiobenzoate mediated reversible addition-fragmentation chain transfer (RAFT) polymerization of NPA in BTMP was carried out. 1H NMR analyses proved that the molecular weight increased linearly with the monomer conversion. The polymer prepared in conventional solvents was atactic while in protic media the syndiotacticity was slightly enhanced.

SYNTHESIS AND PROPERTIES OF HOMOPOLYMER AND COPOLYMERS OBTAINED FROM 1-OCTADECENE WITH ZIRCONOCENE CATALYSTS

Studies related to the behavior of different metallocene catalysts for the homopolymerization of 1-octadecene andits copolymerization with ethylene will be presented. The metallocenes: rac-Et(Ind)_2ZrCl_2, rac-Me_2Si(Ind)_2ZrCl_2 andPh_2C(Flu)(Cp)ZrCl_2 were chosen for the homopolymerization study. They show important differences in catalytic activity athigh temperatures (≥70℃), with rac-Et(Ind)_2ZrCl_2 showing the highest activity. At lower temperatures (≤30℃) thedifferences are negligible. For the copolymerization of ethylene with 1-octadecene only the catalysts rac-Et(Ind)_2ZrCl_2 andrac-Me_2Si(Ind)_2ZrCl_2 were studied. The results show that their catalytic activity is just like that for the homopolymerizationof 1-octadecene, with higher activity for the metallocene with the Et-bridged catalyst. ^(13)C-NMR analysis shows that thecomposition of the copolymerization products depends on the catalytic systems. Copolymers obtained with rac-Me_2Si(Ind)_2ZrCl_2 have greater comonomer incorporation. Thermal analysis shows that poly-1-octadecene synthesized withthe catalyst rac-Et(Ind)_2ZrCl_2 is very dependent on the polymerization temperature. The homopolymer obtained at 70℃presents two endothermal peaks at 41℃ and 53℃, as compared with the one obtained at 30℃ which presents one wider peakwith a maximum at 67℃. For the catalyst rac-Me_2Si(Ind)_2ZrCl_2 this trend is not observed. The type of metallocene and thereaction time do not significantly change the intrinsic viscosity, but the polymerization temperature changes it drastically,giving higher values at lower temperature. Viscosity measurements on the copolymers show that an increase of comonomerconcentration in the feed reduces the molecular weight of the copolymer, and it was also found that for homopolymer, themolecular weight is independent of the catalytic systems.

Ultrasound-responsive Homopolymer Nanoparticles

Nonin vasive ultraso und is a more effective strategy for on-demand drug delivery of polymeric nano particles than many other stimuli.However,the preparation of ultrasound-responsive homopolymer nanoparticles is still very challenging.In this study,we disclose the regulating factors of ultrasound responsiveness of homopolymer nanoparticles and the disaggregation behavior of homopolymer nanoparticle aggregates.Homopolymer nanoparticles such as vesicles and large compound micelles(LCMs)are self-assembled from poly(methoxyethyl methacrylate)(PMEMA)and poly(amic acid)(PAA),respectively.The ultrasound responsiveness of PAA vesicles at metastable state could be regulated by tuning the self-assembly temperature(7^),and was optimized when Ts is around the glass transition temperature(7g)of PAA.However,the PMEMA LCMs did not respond to ultrasound as they are at stable state.On the other hand,poly(2-(2-ethoxyethoxy)ethyl acrylate)(PEEA)could self-assemble into vesicle aggregates or complex micelle aggregates,which were dissociated upon sonication.Overall,the above findings provide us with a fresh in sight for designing ultrasound-responsive polymeric nanoparticles.

Optic and catalytic properties of gold nanoparticles tuned by homopolymers

Gold nanoparticles (GNs) are prepared through in situ reduction using NaBH4 in the presence of homopolymer PDMAEMA. The sizes of the GNs can be adjusted by alternating the molar ratio of gold to DMAEMA. Pure PDMAEMA aqueous solution shows a phase-transition at 50℃ at pH 10 and 25℃ at pH 14, while PDMAEMA-supported GNs aqueous solution shows a phase-transition at 47℃ at pH 10 because of the increasing hydrophobic property resulting from GNs. Due to the pH and tempera-ture-responsible characteristics of PDMAEMA, the resulting PDMAEMA-supported GNs exhibit pH adjustable temperature-responsive characteristics in optic and catalytic aspects. Under an acidic condi-tion (pH 2), the GNs show unchanged surface Plasmon absorbance with a peak of 518 nm in a tem-perature range from 20 to 65℃. Under a basic condition (pH 10), the GNs first show the same absorb-ance with a peak at 518 nm in a temperature range from 20 to 40℃, and then the absorbance red shifts from 518 to 545 nm as temperature increases from 40 to 65℃. When the GNs are used as catalysts to catalyze the reduction of p-nitrophenol, the catalytic activity can be adjusted by changing the permeation of reactants in the PDMAEMA layer at low and high temperatures, respectively.

A homopolymer based on double B←N bridged bipyridine as electron acceptor for all-polymer solar cells

Polymer electron acceptors for all-polymer solar cells （all-PSCs） are usually conjugated copolymers, which contain alternating electron-rich units and electron-deficient units. In this manuscript, we report a conjugated homopolymer （P-BNBP） based on an electron-deficient unit of double B,--N bridged bipyridine, which can be used as electron acceptor for all-polymer solar cells. P-BNBP shows low-lying LUMO energy level of -3.59eV, high absorption coefficient of 1.6 ×10^5Lmo1^-1 cm^-1 at 626nm and moderate electron mobility of 4.37 ×10^-6cm^2V^-1s^-1. AII-PSC devices exhibit power conversion efficiencies of 2.44%-3.04%. These results demonstrate that conjugated homopolymers are promising as electron acceptor materials for alI-PSCs.

新型氧钒配合物的合成及催化乙烯(共)聚合活性研究

烯烃和功能化单体共聚合是制备功能化聚烯烃的重要途径之一。在催化烯烃和功能化单体共聚合过程中,钒系过渡金属催化剂的失活是目前最具挑战的问题。为发现热稳定性好、极性单体耐受性优良的新型钒系催化剂,设计并合成了[NOON]型多齿配体螯合的6,6′-((2-(二甲胺基)乙基)氮甲双基)双(2-甲氧基-4-甲基苯酚)(2a)和6,6′-((2-(吡啶-2-基)乙基)氮甲双基)双(2-甲氧基-4-甲基苯酚)(2b),并通过^(1)HNMR、^(13)CNMR、^(51)VNMR以及XRD的方法确认分子结构。乙烯均聚结果表明,两种钒配合物均能在高温下高活性催化乙烯聚合(活性最高达40.2 kg/mmol V·h),表现出良好的热稳定性。在乙烯与5-降冰片烯-2-甲醇共聚合中,两种钒配合物同样表现出较高活性,极性单体插入率最高可达1.66%。

On the critical behavior of a homopolymer model

We begin with the reference measure P0 induced by simple, symmetric nearest neighbor continuous time random walk on Zd starting at 0 with jump rate 2d and then define, for β≥0, t > 0, the Gibbs probability measure Pβ,t by specifying its density with respect to P0 as dPβ,t/dP0= Zβ,t(0)(-1eβ∫0tδ0(xs)ds),(0.1)where Zβ,t(0)≡E0[eβ∫t0δ0(xs)ds]. This Gibbs probability measure provides a simple model for a homopolymer with an attractive potential at the origin. In a previous paper(Cranston and Molchanov, 2007), we showed that for dimensions d≥3 there is a phase transition in the behavior of these paths from the diffusive behavior for β below a critical parameter to the positive recurrent behavior for β above this critical value. The critical value was determined by means of the spectral properties of the operator△+βδ0, where△ is the discrete Laplacian on Z^d. This corresponds to a transition from a diffusive or stretched-out phase to a globular phase for the polymer. In this paper we give a description of the polymer at the critical value where the phase transition takes place. The behavior at the critical parameter is dimension-dependent.

L-Lactide Homopolymerization and Copolymerization with ε-Caprolactone by Tetrahydrosalen Stabilized Yttrium Borohydride Complex

L-lactide（LLA） homopolymerization and copolymerization with ε-caprolactone（CL） in toluene initiated by tetrahydrosalen-supported yttrium borohydride complex were systematically investigated. A possible mechanism of LLA homopolymerization was proposed according to the 1H-NMR result. In addition, PCL-b-PLLA copolymers were synthesized by sequential addition of monomers and their structure was characterized by GPC, 1H-NMR and 13C-NMR.

Liquid-crystal Assembly of Semiflexible-coil/Homopolymer Blends: a Dissipative Particle Dynamics Study

The liquid-crystal assembly of semiflexible-coil diblock copolymers with coil or semiflexible homopolymers is studied by dissipative particle dynamics simulation. Phase diagrams of the blends and orientation ordering parameters among semiflexible blocks are constructed as a function of chain stiffness and homopolymer volume fraction. For semiflexible-coil/coil blends with varying stiffness of semiflexible blocks, we display the rich phase behaviors of the system transited from coil-coil/coil to rod-coil/coil blends. The disorder- lamellae or lamellae-liquid crystalline transition and ＂dry brush＂ phenomenon induced by coil homopolymers are observed. For semiflexible-coil/semiflexible blends, adding semiflexible homopolymers also leads to a disorder-order transition and even a transition between monolayer and bilayer smectic-A phase. The results demonstrate that blending homopolymers into semiflexible copolymers can induce liquid-crystal assembly and even improve the orientation ordering of semiflexible blocks effectively.

烯烃聚合后过渡金属催化剂研究进展

用于烯烃聚合的后过渡金属催化剂的设计开发在聚烯烃研究领域受到了极大的关注。本文综述了几类后过渡金属催化剂体系的研究进展,包括α-二亚胺型、水杨醛亚胺型、膦磺酸型、膦-氧化膦型和膦酚型催化剂,并简述了通过改变催化剂结构调节催化性能的方法,总结了这些催化剂催化乙烯均聚及乙烯与其他单体共聚时对催化活性、支化度和相对分子质量等方面的影响规律。采用先进后过渡金属催化剂能够合成其他聚合手段无法获得的新型聚合物。

Highly Red Emissive Conjugated Homopolymers Based on Double B←N Bridged Bipyridine Unit

Conjugated homopolymers based on six-member rings,e.g.,polyfluorene,always exhibit blue emission and conjugated homopolymers based on five-member rings,e.g.,polythiophene,can give red emission with low efficiency.In this work,we report a series of new conjugated homopolymers based on six-member rings with high-efficiency deep-red emission.The repeating units of the red light emitting homopolymers are double B←N bridged bipyridine(BNBP)with the boron atoms functionalized with diphenyl,borafluorene,and 2,7-di-tert-butyl-borafluorene groups,respectively.The relationship between the chemical structures and the opto-electronic properties of the monomers and the homopolymers has been systematically studied.The three polymers emit pure red light(λ_(max)=656 nm)or deep red light(λ_(max)=693 nm)with fluorescence quantum efficiency in solution higher than 60%.The polymers can be used as the emitters in solution-processed organic light-emitting diodes with red emission and decent device performance.This work indicates a new strategy to design highly efficient light emitting conjugated polymers.

湿热老化对氰酸酯树脂/酚醛环氧树脂共混物结构与性能的影响

制备了不同摩尔比的双酚 A二氰酸酯 /酚醛环氧树脂共混物 ,测定了共混物和纯氰酸酯聚合物的吸湿曲线 ,用 DMA和 FTIR研究了湿热老化前后共混物结构与性能的变化。结果表明 ,氰酸酯基摩尔分数大于 0 .5的共混物具有明显比聚氰脲酸酯更低的平衡吸湿。老化后共混物的玻璃化转变温度保持率随氰酸酯含量的增加而降低。老化后聚氰脲酸酯的 FTIR谱出现了降解产物的吸收峰 。

超高相对分子质量聚丙烯酰胺合成参数的确定

采用新型复配引发体系，以丙烯酰胺为单体，通过均聚后水解方式聚合，合成出作为油田驱油剂用的超高相对分子质量聚丙烯酰胺．考察了影响合成超高Ｍｒ（聚丙烯酰胺）的因素，确定了聚合工艺：溶液的ｐＨ值为１０．５～１１．５，起始反应温度为２℃，ｗ（单体）为３０％，ｗ（引发剂）为７０×１０－６，ｗ（链转移剂）为１２×１０－６．在优化的聚合条件下，合成出相对分子质量高达２５×１０６，水解度在２０％～３０％可调，过滤比小于１．３的聚丙烯酰胺．

布洛芬高分子前体药物及纳米微球的合成和表征

将非甾体消炎药布洛芬以共价键连接到含双键的甲基丙烯酸 2 羟基乙酯(HEMA)上,制成含布洛芬药物的单体,进而通过自聚或共聚,合成了含布洛芬的高分子药物;采用乳液聚合方法制备了高分子药物纳米微球。研究了影响聚合反应的有关因素,并对所合成的产物用1H NMR,GPC和TEM等检测手段进行了表征。

聚乳酸合成研究现状及展望

对聚乳酸合成研究的直接法、间接法和共聚法的现状进行了综述。

高吸液性树脂的合成及性能

以α-甲基丙烯酰氧乙基三甲基氯化铵与丙烯酰胺为单体 ,采用反相悬浮聚合的方法制得高吸液性树脂。该树脂吸水率可达 60 0 g/g ,吸甲醇率达 60g/g以上。对影响其吸液性能的多种因素 ,如单体、单体配比、油水相比、引发剂及交联剂和分散剂用量等 ,进行了系统的研究 ,并探讨了其吸醇机理。

复合载体Ti系催化剂的乙烯均聚和共聚

研究了乙烯气相均聚、共聚合的复合载体钛系高效催化剂。催化剂基本组份为TiCl4 /ZnCl2 -MgCl2 -SiO2 /AlR3,各组份质量分数为Ti:1 8%～ 2 7% ,Mg2 + :3 0 %～ 4 0 %、Zn2 + :3 5%～ 5 1 %、SiO2 :51 %～ 66%。探讨了催化剂制备条件对聚合性能的影响 ,常压下乙烯气相均聚、共聚合催化效率 6960～ 1 2 1 0 0g/ g ,表观密度 0 3 3～ 0 4 2 g/cm3,2 0～ 2 0 0目聚合物颗粒质量分数为 98%。Φ1 0 0流化床共聚合 ,在 1 0MPa压力下 ,催化效率 4 45～ 887kg/ g ,聚合物MI2 16 为 0 2 6～ 50g/ 1 0min ,熔体流动速率比值MI2 1 6 /MI2 16 为 2 2 7～ 4 7 0 ,熔点 99 6～ 1 2 5℃ ,结晶度 2 0 %～4 9% ,密度 0 880～ 0 92 8g/cm3,支化度 1 1 0～ 4 7 5,该催化剂可制备LLDPE和ULLDPE。

丙烯酰胺在离子液体中的原子转移自由基聚合

在1-丁基-3-甲基咪唑四氟硼酸盐离子液体中以氯化苄为引发剂,氯化亚铜/2,2′-联吡啶为催化剂实现了丙烯酰胺的原子转移自由基聚合(ATRP)。用IR对聚合物的结构进行了表征,证实聚合物链端具有—Cl端基。考察了引发剂用量、催化剂和配体用量、单体用量和反应时间等因素对丙烯酰胺在离子液体中的原子转移自由基聚合的影响。结果表明,反应时间为1.5h时转化率达到31.43%,MnGPC=4451,Mw/Mn=1.38。且80℃下丙烯酰胺在离子液体中的最佳聚合工艺条件为:单体浓度3mol/L,引发剂浓度0.010mol/L,催化剂浓度0.015mol/L,反应时间1h。

膦氮配体半茂钛体系催化乙烯均聚合及乙烯与丙烯共聚合

合成了两种配合物中含有膦、氮的半茂钛催化剂，研究了甲基铝氧烷、四（五氟苯基）硼酸盐为助催化剂，不同n（Al）∶n（Ti）对乙烯均聚合及聚合物相对分子质量及其分布的影响。研究了催化剂用量、原料配比、反应压力、反应时间对乙烯与丙烯共聚合及共聚物组成、相对分子质量及其分布的影响。结果表明：合成的膦氮配体半茂催化剂可有效催化乙烯均聚合，在常压下，聚合活性可达0.62×106g/（mol·h），也可以有效催化乙烯与丙烯共聚合，与高活性茂金属催化剂催化效率相近；用该催化剂制备的高相对分子质量乙丙共聚物的相对分子质量分布窄，符合单活性中心催化剂的特点；共聚物的序列结构研究表明，乙烯与丙烯竞聚率之积接近1，共聚物无规性好。

松香甲基丙烯酸-β-羟乙酯均聚和共聚研究

将松香与甲基丙烯酸-β-羟乙酯(HEMA)合成的酯化物,通过自由基聚合的方法制备了均聚物和与苯乙烯(St)的共聚物,用红外光谱(IR)和核磁共振氢谱(1HNMR)表征了产物的分子结构,分别用综合热分析仪(TGA)和差示扫描量热仪(DSC)表征了产物的热稳定性和玻璃化转变温度。结果表明:松香HEMA酯的均聚反应较难进行,过氧化苯甲酰是其均聚反应较好的引发剂;松香HEMA酯与苯乙烯(St)较易进行共聚反应,偶氮二异丁腈是共聚反应较好的引发剂;共聚物的黏度和玻璃化转变温度随苯乙烯的用量的增加而增加,而均聚物热稳定性好于共聚物。