SYNTHESIS AND CHARACTERIZATION OF WELL-DEFINED BLOCK COPOLYMERS CONTAINING PENDANT,SELF-COMPLEMENTARY QUADRUPLE HYDROGEN BONDING SITES

The title block copolymer (defined as PSUEA) containing pendant,self-complementary quadruple hydrogen bonding sites has been prepared successfully by three steps.First,poly(styrene-b-2-hydroxyethyl acrylate) (defined as PSHEA) was prepared by living radical polymerizing 2-hydroxyethyl acrylate (HEA) initiated by polystyrene (PSt) macro- initiator,which was prepared via nitroxide-mediated polymerization (NMP) technique.After treated by excessive 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI),...

MOLECULAR DYNAMICS SIMULATION ON VIERATIONAL SPECTROSCOPIC FEATURES OF HYDROGEN BONDS IN CRYSTALLINE POLYMERS

Introduction The molecular dynamics simulation technique has recently proved to be a suitable alternative approachfor simulation of vibrational spectroscopy. In this study, molecular dynamics was utilized to understandlow frequency vibrations in highly ordered poly(ρ-phenylene terephthalmide) (PPTA). A key structuralfeature of this polymer is the presence of hydrogen bonds. There is little question that this strong localized

SYNTHESIS OF MONODISPERSE HOLLOW POLYMER MICROSPHERES WITH FUNCTIONAL GROUPS BY DISTILLATION PRECIPITATION POLYMERIZATION

Monodisperse hollow polymer microspheres having various functional groups on the shell-layer, such as carboxylic acid, pyridyl and amide, were prepared by two-stage distillation precipitation polymerization in neat acetonitrile in the absence of any stabilizer or additive, during which monodisperse poly（methacrylic acid） （PMAA） afforded from the first-stage polymerization was utilized as the seeds for the second-stage polymerization. The shell layer with different functional groups was formed during the second-stage copolymerization of either divinylbenzene （DVB） or ethyleneglycol dimethacrylate （EGDMA） as crosslinker and the functional comonomers, in which the hydrogen-bonding interaction between the carboxylic acid group of PMAA core and the functional groups of the corresponding comonomers, including carboxylic acid, amide and pyridyl, played an essential role for the formation of monodisperse core-shell functional microspheres. The hollow polymer microspheres were then developed after the subsequent removal of PMAA cores by dissolution in ethanol under basic condition. Transmission electron microscopy （TEM） and scanning electron microscopy （SEM） were used to determine the morphology of the resultant PMAA core, functional core-shell microspheres and the corresponding hollow polymer microspheres with different functional groups. FT-IR spectra confirmed the successful incorporation of the various functional groups on the shell layer of the hollow polymer microspheres.

Polymeric Iodoplumbate Incorporating Copper Iodide Complex Cation Layer:Structure and Theoretical Study of a New Semi-conductive Hybrid:{[Cu(Ⅱ)(bipy)_2I][PbI_3](H_2O)_2}_n

A new iodoplumbate polymer incorporating copper iodide complex cation {[Cu（Ⅱ）（bipy）2I][PbI3]（H2O）2}n 1（bipy = 2,2＇-bipyridine） has been synthesized and structurally determined.It crystallizes in the triclinic system,space group P1 with a = 7.979（4）,b = 14.538（11）,c = 15.853（8）,α = 110.77（2）,β = 97.955（18）,γ = 104.88（2）°,V = 1607.3（17）3,Z = 2,C20H16CuI4N4O2Pb,Mr = 1122.72,Dc = 2.320 g/cm3,F（000） = 1006,μ（MoKα） = 9.753,the final R = 0.0627 and wR = 0.1741 for 4846 observed reflections with Ⅰ 〉 2σ（Ⅰ）.Structural analysis indicates that 1 consists of 2-D {[Cu（Ⅱ）（bipy）2I]}nn＋ cation layers（based on π-π interaction and hydrogen bonds） and [PbI3]nn-polyanions.The C-H···I hydrogen bonds between {[Cu（Ⅱ）（bipy）2I]}nn＋ cation layers and [PbI3]nn-polyanions lead to the formation of an interesting 3-D network.Optical absorp-tion spectrum indicates that 1 is a semiconductor,which is further validated by DFT calculation.Its electronic structure is also discussed.

Atomic layer deposition of ultrathin layered TiO_2 on Pt/C cathode catalyst for extended durability in polymer electrolyte fuel cells

This study shows the preparation of a TiO2 coated Pt/C（TiO2/Pt/C） by atomic layer deposition（ALD）,and the examination of the possibility for TiO2/Pt/C to be used as a durable cathode catalyst in polymer electrolyte fuel cells（PEFCs）. Cyclic voltammetry results revealed that TiO2/Pt/C catalyst which has 2 nm protective layer showed similar activity for the oxygen reduction reaction compared to Pt/C catalysts and they also had good durability. TiO2/Pt/C prepared by 10 ALD cycles degraded 70% after 2000 Accelerated degradation test, while Pt/C corroded 92% in the same conditions. TiO2 ultrathin layer by ALD is able to achieve a good balance between the durability and activity, leading to TiO2/Pt/C as a promising cathode catalyst for PEFCs. The mechanism of the TiO2 protective layer used to prevent the degradation of Pt/C is discussed.

Hydrothermal Syntheses, Crystal Structures and Fluorescence of a Copper(I) Polymer and a Salt with H_2SO_4 Based on a Pyrimidine Building Block

Based on the building block of 2-phenyl-4,6-di（pyridin-2-yl）pyrimidine （L = C20H14N4）, a Cu（I） polymer [（CuC20H14N4）（CuCl2）]∞ and a salt with H2SO4 [（C20H16N4）（HSO4）2] have been synthesized by hydrothermal method and characterized by X-ray single-crystal diffraction. In the Cu（Ⅰ） polymer, although the central metal ions of Cu（Ⅰ） directly coordinate with the building block L, they still do not assembly expected grid-type complexes and there exists a one-dimensional chain constructed through coordinate bonds. In the salt, hydrogen bonds along with two kinds of π…π supramoleuclar interactions fabricate two-dimensional （2D） networks which further generate a 3D supramolecular architecture via interlayer π…π interactions. Fluorescent spectra show that the L emits blue fluorescence and its Cu（Ⅰ） polymer and salt decrease the fluorescent intensity.

A MORPHOLOGICAL STUDY OF POLY(DIVINYLBENZENE-co-ACRYLIC ACID) IN CROSSLINKING PRECIPITATION POLYMERIZATION

Divinylbenzene-80 （DVB-80） and polar monomer acrylic acid （AA） having hydrogen bonding at a total monomer loading of 5 vol% were precipitated-copolymerized in a variety of organic solvents with 2,2＇-azobis（isobutyronitrile） （AIBN） as initiator. The experiments were investigated from a two-dimensional matrix, i.e., the actual crosslinking degree of DVB varying from 0 to 80% and the solvent composition varying from 0 to 100% of toluene mixture with acetonitrile, when the mixture of acetonitrile and toluene was used as the reaction solvent. Under various reaction conditions, six distinct morphologies including soluble polymers, swellable microgels, coagulum, irregular microparticles, and nano-/micrometer microspheres were formed and the structures of these polymer architectures were described. A morphological map was utilized to discuss the effects of both crosslinking degree of DVB and composition of solvent on the transitions between morphology domains. The results demonstrated that the microspheres are formed by an internal contraction due to the marginal solvency of the continuous phase and the crosslinking of the polymer network through the covalent bonding from DVB as well as the interchain hydrogen-bonding between the carboxylic acid units.

Synthesis of Highly-Selective Fibrous Adsorbent by Introducing 2-Ethylhexyl Hydrogen-2-Ethylhexylphosphonate for Scandium Adsorption

2-ethylhexyl hydrogen-2-ethylhexylphosphonate (EHEP) is commonly used as a metal extractant because it has a particular affinity for rare-earth metals like Scandium (Sc). To develop a highly-selective adsorbent of Sc(III), EHEP was introduced as a functional group onto a polyethylene fabric with radiation-induced graft polymerization(RIGP). The adsorption performances for Sc(III) were evaluated with aqueous solutions containing Sc(III) and Fe(III) in bath and column tests. As a result of column test, the adsorption capacities of Sc(III) and Fe(III) until the bed volume reached 5000 were 5.22 and 0.12 mg/g, respectively. It means that the amount of collected Sc(III) by the EHEP adsorbent was approximately 44 times higher than that of Fe(III). These results indicate that the grafted adsorbent containing EHEP has an extremely high selectivity for Sc(III) adsorption.

Syntheses,Structures and Properties of Two New Coordination Polymers with Flexible Ligands as Linkers

Two new coordination polymers,[ZnL1]n（1,H2L1 = 5-（4-pyridyl）-methoxyl isophthalic acid） and[Ni（L2）2（H2O）4]n（2,HL2 = 4-（pyridin-4-ylmethoxy）benzolic acid）,have been synthesized and characterized by elemental analysis,PXRD,IR spectra,and single-crystal X-ray diffraction.Compound 1 has a three-dimensional framework constructed by 6-bridged L1^2- anions connecting the Zn2（O2C）4 paddlewheel-like units.Compound 2 contains a mononuclear molecular unit,and the central nickel atom adopts a slightly distorted octahedral geometry by two nitrogen atoms from different L2^- ligands and four oxygen atoms from water molecules.These molecular units link each other via four types of O-H…O hydrogen bonds to form an extended three-dimensional（3D） supramolecular network.The thermal and photoluminescent properties of 1 and 2 have also been investigated.

Crystal Structure of the Coordination Polymer of Sodium with Hydrazone Derivant of Acetoacetanilide

One new polymer, [Na（NPHSNPAB）（CH3OH）]n, where NPHSNPAB stands for Nphenyl-2-[2-hydroxy-3-sulfo-5-nitrophenylhydrazone]butadione-1,3, has been synthesized and characterized by ^1H NMR and FTIR spectroscopy and single-crystal X-ray diffraction. For this complex： C（17）H（17）N4NaO9S, Mr = 476.39, triclinic system, space group P1, a = 8.8741（18）, b = 10.942（2）, c = 12.039（2） A, α = 65.74（3）, β = 77.49（3）, γ = 84.30（3）o, V = 1040.3（4） A3, Z = 2, Dc = 1.521 g/cm^3, λ = 0.71073 A, F（000） = 492, S = 1.106, R = 0.0614 and w R = 0.1423 for 2945 observed reflections with I 〉 2（I）. X-ray structural analysis revealed that the structure of NPHSNPAB framework was almost planar by C–H···O, N–H···O, O–H···O, and O–H···S hydrogen bonds. Moreover, sodium（I） center was bound by six O and one N atoms, forming the coordination polymer. The molecular packing diagram showed complicated hydrogen bonds and π···π stacking interaction in the polymer. The average bond distance of the two dicyclic units（3.768 A） indicated strong π···π stacking interaction. The complex displays greenyellow emission at room temperature.

STUDIES ON THE STATE OF PALLADIUM AND HYDROGENATION ACTIVITY OF RESIN SUPPORTED PALLADIUM──TIN OXIDE CATALYSTS

Several Pd--SnO2/ D3520 and Pd--PbO / D3520 catalysts with Pd/ D3J20, SnO2 / D3520 and PbO / D3520 catalysts as rference were studied by means of IR and XPS. Interaction between Pd and the second metal or between metal and support was observed. Results show that there is a strong interaction between Pd and the second metal, but there is not an obvious interaction between metal and support. The active constituent is Pd￣0. Hydrogenation activity of the catalysts is altered because of the interaction between Pd and the second,metal.The activity of the catalysts for hydrogenation has relation to outer layer valence electron density of Pd.

ADSORPTION OF PHENOLIC COMPOUNDS ONTO THE SPHERICAL MACROPOROUS ADSORBENT BASED ON UREA-FORMALDEHYDE CONDENSED POLYMER

Absorption of phenol, catechol and resorcinol. which vary in their ability to interact with the adsorbent through hydrogen bond, were used to investigate the adsorption mechanistic interaction. The adsorption enthalpies of the above mentioned compound onto the adsorbent were calculated and thermodynamic analysis was carried out. The results showed the adsorbent with the lowest adsorption enthalpies for the sorbate such as catechol with intermolecular hydrogen bond also display the lowest adsorption affinity On the other hand the more of the groups available for hydrogen bond interaction. the higher of the adsorption affinity These observations support the contention that phenol adsorption is driven predominantly by specific interaction of the solute with active sites on the surface of the adsorbent.

PREPARATION OF POLY(ETHYLENEGLYCOL-co-ACRYLIC ACID) MICROSPHERES WITH DIVINYLBENZNE AS CROSSLINKER BY DISTILLATION-PRECIPITATION POLYMERIZATION

Monodisperse poly（poly（ethyleneglycol） methyl ether acrylate-co-acrylic acid） （poly（PEGMA-co-AA）） microspheres were prepared by distillation-precipitation polymerization with divinylbenzene （DVB） as crosslinker with 2,2＇- azobisisobutyronitrile （AIBN） as initiator in neat acetonitrile without stirring. Under various reaction conditions, four distinct morphologies including the sol, microemulsion, microgels and microspheres were formed during the distillation of the solvent from the reaction system. A 2D morphological map was established as a function of crosslinker concentration and the polar monomer AA concentration, in comonomer feed in the transition between the morphology domains. The effect of the covalent crosslinker DVB on the morphology of the polymer network was investigated in detail at AA fraction of 40 vol%. The ratios of acid to ethylene oxide units presenting in the comonomers dramatically affected the polymer-polymer interaction and hence the morphology of the resultant polymer network. The covalent crosslinking by DVB and the hydrogen bonding crosslinking between two acid units as well as between the acid and ethylene oxide unit played key roles in the formation of monodisperse polymer microspheres.

环烯烃开环易位聚合物的合成

采用MoCl_(5)为核心的齐格勒-纳塔催化剂合成降冰片烯-四环十二烯的开环易位聚合物,实现稳定的100%单体转化率,凝胶率0%。并采用Al_(2)O_(3)负载的Ru催化剂和SiO 2/Al_(2)O_(3)负载的Ni金属催化剂对相同的降冰片烯-四环十二烯开环易位聚合物进行非均相加氢,可实现100%的加氢率,且简单过滤即可将催化剂与聚合物溶液完全分离。两种加氢催化剂的产品具有不同的性质,Ni负载催化剂最佳反应条件:催化剂含量10%、反应温度190℃、初始氢气压力4 MPa、反应时间2 h,加氢产物的熔融指数76 g·min^(-1),玻璃化转变温度126℃;Ru负载催化剂最佳反应条件:催化剂含量2%、反应温度180℃、初始氢气压力4 MPa、反应时间2 h,加氢产物的熔融指数10 g·min^(-1),玻璃化转变温度131℃。

纳米丁腈橡胶胶乳的制备与催化加氢

采用常规乳液聚合法结合低温间歇聚合工艺制备了丁腈橡胶胶乳,使用自制钌系催化剂对该胶乳进行乳液加氢,系统研究了催化剂用量和氢气压力对丁腈橡胶胶乳加氢效果的影响规律。结果表明,所制备丁腈橡胶胶乳的平均粒径为69.13 nm,加氢前后胶乳的粒径基本保持不变且胶乳稳定性良好;氢气压力越大催化加氢效果越好;当催化剂质量分数为0.017 5%时,可制得氢化度为99%以上且不含凝胶的产品。

苯乙烯阻聚剂的研究及应用进展

随着我国环境保护政策的日益严格,优化、更新替代苯乙烯行业的阻聚剂是关注的热点之一。本文主要从聚合反应的抑制机制等方面综述了硝基苯酚类、醌类、酚类、羟胺类、芳胺类、吡啶类及多硝基型化合物及其复配阻聚剂的研究进展,重点分析苯乙烯阻聚剂特点、研究及应用现状。结果显示,高效复配阻聚剂具有绿色环保、低氮排放、化学性质稳定、毒性低、剂量小和成本低等优点,它是苯乙烯生产中安全环保、长周期稳定运行、绿色生产的关键之一。

国产HR催化剂在高性能聚丙烯EP548RQ生产的应用

采用HR催化剂在400 kt/a单环管聚丙烯Spheripol装置上生产了高流动、高刚性抗冲共聚聚丙烯EP548RQ,考察了HR催化剂生产期间,粉料细粉含量及装置运行情况、装置活性、烷基铝(TEAL)和外给电子体(Donor)用量、立构定向能力、氢调性、抗冲共聚能力等,并测试了EP548RQ的力学性能。结果表明:与进口催化剂对比,装置运行更稳定,所产粉料的细粉含量更低,更利于装置长周期运行。HR催化剂活性提高约36%,烷基铝(TEAL)用量减少20%(质量分数),外给电子体用量减少75%(质量分数),氢气加入量降低约42%,所产均聚料的等规度提高0.7%(质量分数),所得产品气味低,无塑化剂,树脂品性得到提升。

纤维素在ZnCl_2水溶液中的溶解性能及再生结构

比较了不同质量分数的ZnCl2水溶液溶解不同聚合度纤维素的能力,发现:质量分数为65.0%以下的ZnCl2水溶液不能溶解纤维素;当ZnCl2水溶液的质量分数达到或超过65.0%时,未被水分子饱和的Zn2+可与纤维素分子链作用,使纤维素溶解,且65.0%的ZnCl2水溶液的溶解效果最佳;随着纤维素聚合度的增大,其溶解性能下降;经ZnCl2水溶液溶解后的再生纤维素的聚合度下降.广角X-射线衍射(WAXD)分析表明再生纤维素为纤维素Ⅱ结晶变体;傅里叶变换红外光谱(FT-IR)显示ZnCl2水溶液是纤维素的非衍生化溶剂,且再生纤维素分子内的氢键减弱.

低相对分子质量反式-1,4-聚异戊二烯蜡的合成

以H2 气作为相对分子质量调节剂 ,采用MgCl2 负载TiCl4催化体系催化异戊二烯溶液淤浆聚合及本体沉淀聚合 ,合成低相对分子质量反式 1 ,4 聚异戊二烯蜡。研究了聚合条件如H2 气分压、聚合温度、时间、催化剂用量等对相对分子质量、催化剂效率和聚合物结构的影响。结果表明 ,H2 气能明显调节聚合物的相对分子质量。当H2 气分压为 2 4MPa时 ,聚合物的特性粘数降至 0 2 3dL/g,相应粘均相对分子质量为 3 80 0 ,数均相对分子质量约为 1 0 0 0。结构分析表明 ,所得聚合物反式 1 ,4 结构摩尔分数为 92 %以上 ,结晶度 3 0 %左右。聚合物相对分子质量分布指数ID为 5 0～ 80。

水性引发剂浓度对MMA/n-BA/H-PDMS微乳液聚合的影响

以辛基酚聚氧乙烯醚(OP-10)和OP-4、十六烷基三甲基溴化铵(CTAB)为复合乳化剂,正戊醇为助乳化剂,含氢聚二甲基硅氧烷(H-PDMS)、甲基丙烯酸甲酯(MMA)、丙烯酸正丁酯为聚合单体,以水溶性过硫酸铵(APS)-亚硫酸氢钠(NaHSO3)为氧化还原引发剂,采用微乳液聚合方法,制备了4种引发剂浓度不同的聚合物微乳液,研究了引发剂浓度对MMA/n-BA/H-PDMS的微乳液共聚合的影响。通过FT-IR和1 H-NMR分析证明,微乳液体系中的聚合物含有氢聚硅氧烷/丙烯酸酯共聚物;实验表明,当引发剂浓度太低时,聚合体系存在引发诱导效应;而当引发剂浓度适当提高时,聚合过程存在明显的恒速期;但当引发剂浓度较高时,聚合过程无明显恒速期,继续提高引发剂浓度,聚合速率明显变大,其聚合速率的最大值也更高。通过动力学研究,分别得到了聚合速率与产物特性黏度的动力学关系式:Rp∝[APS]0.75,[η]∝[APS]-0.07。另外,实验结果表明,随着聚合转化率的提高,乳胶粒径增大。在这些研究基础上初步探讨了微乳液聚合机理。