链结构及频率对嵌段聚醚氨酯介电谱的影响

不少研究者用介电驰豫的方法对聚合物进行了广泛的研究^[1-5].对多嵌段的两相体系,介电驰豫的方法很灵敏.我们曾用此法研究了不同扩链剂及软段为聚四亚甲基醚二醇(PTMG)嵌段聚醚氨酯(SPEU)的分子运动,观察到软段结晶的α_c峰^[6].本文用介电驰豫方法进一步考察软段链结构不同对温度谱的影响,以及不同驰豫单元的活化能.     

静电纺丝法制备NiO纳米纤维及其表征

纳米级NiO因具有优良的催化和热敏等性能而被广泛用于催化剂^[1]、电池电极^[2,3]、光电转化材料^[4～6]、电化学电容器^[7～8]等诸多方面.迄今,已成功地制备出N iO的纳米颗粒^[9]、纳米线^[10]及纳米薄膜^[11],但是对于具有准一维结构的NiO纳米纤维的制备及性能研究尚未见报道.     

两种卟啉化合物在Ag溶胶表面的紫外-可见吸收光谱和表面增强拉曼散射光谱研究

表面增强拉曼散射(SERS)自1974年被Fleischmann等^[1]发现以来,日益受到人们的重视.通过SERS谱图分析,可以获得物质结构及其与基体作用的信息.由于SERS可使拉曼信号增强10⁵~10⁶倍^[2],并且在某些情况下银胶还能使表面吸附质的荧光猝灭^[3,4], SERS常用来检测一些普通拉曼光谱难以检测的样品和考察界面络合物的形成.     

苯甲酸及其酯类衍生物的分子印迹机理的研究

分子印迹聚合物(M IP)是一种具有分子识别能力的新型高分子材料^[1～3].对其研究的重要问题之一是如何获得对相应模板化合物具有特异性结合的聚合物,这除了受模板分子结构特征的影响外,同时在很大程度上还受各种聚合物制备条件的影响,比如功能单体^[4～6]、溶剂^[7]及辅助金属离子的影响^[8]等.我们成功地通过计算模板分子与功能单体间的相互作用,预测了一些模板分子的印迹原性(产生印迹效应的性质)的强弱^[9],同时对几十种小分子化合物的分子印迹原性与结构之间的关系进行了讨论^[10].本文以苯甲酸、对氨基苯甲酸、对羟基苯甲酸及其酯的衍生物(结构见下式)为模板,在不同的功能单体和溶剂体系中制备了相应的分子印迹聚合物,研究了模板分子中不同取代功能基的印迹作用的相对强弱,探讨了功能基的印迹作用强弱与聚合反应体系溶剂极性间的相关性.     

硝基磺酚C光度法测定蛋白质的研究

蛋白质的定量分析是生化研究、临床化验和食品检验等领域经常涉及的内容.以有机小分子作光谱探针测定蛋白质,如甲基橙^[1,2]、考马斯亮蓝G-250^[3]、溴酚蓝^[4]、溴甲酚绿^[5]和偶氮胂Ⅲ^[6]等已得到研究.     

聚酯聚氨酯透气性的正电子研究

用正电子湮没寿命谱(PALS)研究了温度和PEG含量对以聚己二酸丁二醇酯(PBA)为软段的聚酯聚氨酯的自由体积特性和透气性的影响.实验结果表明,自由体积空洞的体积随着温度的升高而增加,分布变宽,导致透气性增大.不同PEG含量的聚酯聚氨酯PBA-10,PBA-15和PBA-20的水汽渗透系数(WVP)基本相同.结果表明,在这类聚氨酯中,影响透气性的主要因素不仅是自由体积,而且与材料的亲水性有关.     

纸上反相分配层析与液液萃取分离2-乙基己基膦酸单(2-乙基已基)酯对镧系元素反相分配层析研究

Cerrai^[1,2]等曾研究了二(2-乙基己基)磷酸(HDEHP)对稀土元素的反相层析,并用斜率法测定了萃合物组成.Cvjelicanin^[3]用反相层析研究了二丁基磷酸对铍、镧及铈的萃取机理和平衡常数.我们以往的研究结果说明,配位体结构的极性效应和空间效应对分离金属离子的反相层析行为与液液萃取极相似^[4,5].     

质子化甜菜碱阳离子与双三氟甲磺酰亚胺阴离子相互作用的理论研究

利用密度泛函理论(DFT)方法, 在B3LYP/6-311＋G(d,p)水平下, 对质子化甜菜碱阳离子与双三氟甲磺酰亚胺阴离子形成的气态阴阳离子对([Hbet][Tf₂N])进行理论研究, 通过几何结构优化和频率分析得到势能面上的六个稳定构型. 计算结果表明[Hbet]^＋和[Tf₂N]^－之间能够形成较强的氢键相互作用, 氢键相互作用的稳定化能主要来源于[Tf₂N]^－中O, N原子的孤对电子和[Hbet]^＋中参与形成氢键的O-H, C-H反键轨道之间的相互作用. 自然布局分析(NPA)给出气态[Hbet][Tf₂N]离子对中阴阳离子间的电荷转移比传统离子液体中电荷转移的数值小. AIM (atoms in molecules)分析得到[Hbet]^＋和[Tf₂N]^－之间的氢键相互作用以静电作用为主. 通过实验和理论结果相比较, 初步探讨影响离子液体熔点及其对金属离子选择性溶解的结构因素.     

杯[4]单硫(硒)杂冠-5的合成及其对金属离子的识别性能研究

从简单无机硫、硒化合物直接合成冠醚环上含硫、硒杂原子的杯[4]单硫杂冠-5及杯[4]单硒杂冠-5;化合物的结构经¹HNMR、MS及元素分析确证.并研究了它们对Na⁺,K⁺,NH⁴⁺,Co²⁺,Ni²⁺,Ag⁺及Hg²⁺的两相萃取性能,发现其对Ag⁺、Hg²⁺有较好的识别能力.     

碳苷研究(Ⅵ)——1-芳基-D-吡喃葡萄糖碳苷的快原子轰击质谱

快原子轰击质谱(FAB-MS)是近几年发展起来的一种质谱新技术^[1],特别适于极性大、不易挥发和对热不稳定的化合物,已用于多肽^[2]、核酸^[3]及苷^[4]的结构测定。     

Graft interpenetrating polymer networks of polyurethane and epoxy. I. mechanical behavior

Polyurethanes (PU) based on poly(butylene adipate) [PU(PBA)] and poly(oxypropylene) [PU(PPG)] polyols have bean introduced into the diglycidyl ether of bisphenol A (epoxy) to form interpenetrating polymer networks (IPNs) with a PU-grafted epoxy structure (graft-IPNs). The tensile strength in both PU(PPG)/epoxy and PU(PBA)/epoxy systems increases with increasing PU content. Maximum values emerge at PU/epoxy ratios between 19/81 and 27/73. This is explained as a result of the presence of the graft structure, which leads to more intimate interpenetration between the PU and epoxy in the graft-IPNs. Dynamic mechanical analysis (DMA) indicates that the PU introduced can be incorporated in either the α or β transition domain of the epoxy. The tensile strength of the resulting graft-IPNs shows a significant improvement as the PU is incorporated in the α transition domain of the epoxy. It is also noted that suitable amounts of PU incorporated in both the α and β transition domains of epoxy can increase the tensile strength of the IPNs, while excessive amounts of PU introduced into both α or β transition domains tend to decrease the tensile strength of the graft-IPNs.     

水性聚氨酯乳化过程中相转变的研究

本文合成了单官能团小分子物质封端的脂肪族水性聚氨酯预聚物 ,通过考察预聚物加水乳化过程中粘度及电导率的变化 ,研究了其相转变行为 .实验结果表明 ,随着软段分子量升高 ,体系的相转变点后延 ;聚酯体系的相转变比聚醚体系的相转变发生得早 ;[NCO]/ [OH]值越接近 1,体系的粘度就越高 ,相转变发生所需的水含量也越高 ;羧基含量及中和度也会对分散体系的相转变产生影响 .通过选择合适的条件 ,可以实现对乳化过程的优化     

聚氨酯环氧树脂乳液互穿聚合物网络结构与性能研究

分别以聚四氢呋喃(PTMG)和聚己二酸丁二酯(PBA)为聚氨酯(PU)软段,制备了高环氧树脂(EP)含量的PU/EP乳液互穿聚合物网络(LIPN).通过红外光谱,动态力学分析,原子力显微镜等研究了不同类型软段对LIPN结构与性能的影响.结果表明,LIPN结构已经形成,PU与EP间无化学键结合.以PBA为PU软段制备的LIPN中PU与EP相容性更好,分相程度相对低,互穿程度高,导致EP对PBA软段运动的限制作用较强,EP含量的变化对LIPN的玻璃化转变温度影响更大.研究样品的力学性能和溶剂溶胀性能发现,PBA为软段制备的LIPN均优于以PTMG为软段制备的LIPN,水溶胀率等有大幅减小,表现出明显的互穿协同效应.     

The effect of soft-segment length and concentration on phase separation in segmented polyurethanes

Three series of polyurethanes, based on three polyols, diphenylmethane diisocyanate (MDI), and three chain extenders were synthesized. Polypropylene glycol (PPG) soft-segment length (MW 1000, 2000, and 3000), soft-segment concentration (30%, 50%, and 70%), and the type of chain extender (ethylene glycol, butane diol, and hexane diol) were varied and their effect on the amount of phase separation studied. Methods for assessing phase separation quantitatively, based on shifts of the glass transition temperature T_g and the enthalpy jump at the glass transition were tested. It was shown that they give incorrect results, especially with PPG 1000 as the soft segment. Dependence of the soft segment T_g on the polyol length was explained by the “network effect.” True phase mixing was found only with PPG 1000 series at low soft-segment concentration, whereas, no clear indication of the phase mixing with PPG 2000 and PPG 3000 based polyurethanes was observed.     

Waterborne polyurethanes and their properties

Anionomer-type waterborne polyurethanes (PUs) were obtained from poly(β-methyl-δ-valerolactone) glycol (PMVL) and isophorone diisocyanate, following a prepolymer mixing process. The soft-hard segment phase separation in response to the variations of composition and structure of PU has been studied from the dynamic mechanical measurements of the emulsion cast films. The structural variation included ionic and hard segment content, molecular weight of NCO-terminated prepolymer, and type and length of the soft segment. It was found that phase separation is more sensitive to the soft segment length, rather than the soft segment content. With only phase separation, the rubbery modulus was significant even with lower hard segment content. Phase separation was much more pronounced with PU from poly(tetramethylene adipate) glycol, rather than from PMVL and poly(caprolactone) © 1996 John Wiley & Sons, Inc.     

Effect of soft segment component on moisture‐permeable polyurethane films

The effect of soft segment component and molecular weight combination on moisture‐permeable polyurethane films was studied. Moreover, water sorption phenomenon in films was observed with infrared analysis. As for soft segment components, PTMG/PEG and PTMG/PPG were used and molecular weight combinations were changed. Different tendency appeared in the experimental results corresponding to PEG system and PPG system. Moisture permeability P in PEG system increased with increasing PEG content, but P changed little in the case of PPG system. Both hydrogen‐bonded concentration by infrared measurement and the higher order term Δh of Mooney–Rivlin plot by stress–strain relationships indicate the existence of aggregate structure of hard segment. It is considered that ether group in PEG is more active than that in PPG. Therefore, small size of aggregate structure indicated as Δh appears in PEG system owing to inhibition of aggregate structure growth. Whereas, ether group in PPG system does not inhibit hydrogen bond in urethane group and large size of aggregate structure appears. From water affinity relationship analysis, hydrophilicity of samples with PTMG/PEG = 2000/2000 increased with increasing PEG content. Consequently, it is suggested that not only size but also hydrogen‐bonded concentration of urethane group in aggregate structure affects moisture permeability. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 573–583, 2006     

嵌段聚酯型聚脲氨酯弹性体的热转变研究

用示差扫描量热法(DSC)研究了基于二苯基甲烷二异氰酸酯(MDI)、乙二胺(ED)和聚己二酸丁二醇酯(PBA)(M.W.1975和M.W.1228)两系列嵌段聚酯型聚脲氨酯(PUU)弹性体,并考察了这些材料在不同退火条件下软段结晶的热变化。结果表明:在这些弹性体中,PBA 1975系列具有比PBA1228系列更低的软段玻璃化温度,说明前者的相分离较好.软段T_(gs)和硬段T_(gh)对硬段含量的变化不敏感.退火样品的DSC结果表明:软段结晶具有两个吸热峰,提出在软段相中存在两种晶型(P_l和P_h)的假设,分析了两种晶型产生的原因.     

Protein resistance of polyurethane with hydrophilic and hydrophobic soft segments

Polyurethane (PU) containing poly(propylene glycol) (PPG) or poly(tetramethylene oxide) (PTMG) soft segments have been prepared by two‐step condensation polymerization. The former (PPG‐PU) with a lower critical solution temperature (LCST) at ～21 °C can change from hydrophilic to hydrophobic, whereas the latter (PTMG‐PU) is hydrophobic at a temperature above 0 °C. The adsorption of fibrinogen, bovine serum albumin, or lysozyme on such a PU surface in aqueous solution has been investigated by use of quartz crystal microbalance with dissipation (QCM‐D) and surface plasmon resonance (SPR) in real time. PPG‐PU surface exhibits protein resistance at a temperature below the LCST of PPG, but it significantly adsorbs proteins at a temperature above the LCST. On the other hand, the hydrophobic PTMG‐PU surface adsorb the proteins at any temperatures investigated, in contrast with the hydrated poly(ethylene glycol) exhibiting excellent protein resistance. The hydration and dehydration of the polymers at different temperatures were confirmed by Raman spectroscopy. Our study demonstrates that the protein resistance of polymers is determined by their hydration. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1987–1993, 2010     

Gas permeability of cupric ion containing HTPB based polyurethane membranes

For the purpose of oxygen enrichment from air, the gas permeability and selectivity of an ionic polyurethane membrane was under investigation. Membranes of ionic polyurethane were prepared by step-growth polymerization of hydroxyl terminated polybutadiene (HTPB) and 4,4′-dicyclohexylmethane diisocyanate (H₁₂MDI). The ionic group was introduced by adding N-methyldiethanolamine (MDEA) as the chain extender of which the tertiary amines were complexed with cupric ions. The effect of hard segment content, polymerization method, peroxide introduction, and the amount of cupric ion on gas permeability were investigated. It was found that the binding of hard segment and the flexibility of soft segments had subtle effects on gas permeability. Membranes of the same composition were synthesized through two different procedures, one- and two-stage polymerization. The former contains large hard segment of cluster aggregation and flexible soft segments had a higher gas permeation rate. When a crosslinker, benzoyl peroxide, was added, the crosslinkage within soft segments hindered cluster formation by hard segment aggregation, the permeability increased. Furthermore, CuCl₂ addition enhanced hard segment aggregation, more hard segments formed cluster aggregates and less dispersed in soft segment region, which also increased permeability. However, excess CuCl₂ addition resulted in CuCl₂ piling up in the soft segment region, which restricted the movement of soft segments and therefore reduced the gas permeability.     

丁苯、丁腈基聚氨酯的形态与性能

用示差扫描量热法 (DSC)、红外分光光度计 (FTIR)和原子力显微镜 (AFM)研究了端羟基聚丁二烯 苯乙烯共聚物 (HTBS)、端羟基聚丁二烯 丙烯腈共聚物 (HTBN)和端羟基聚丁二烯 (HTPB)与甲苯二异氰酸酯、1 ,4 丁二醇构成的溶液法聚二烯烃基聚氨酯 (PU)的形态结构 .结果表明HTPB和HTBS基PU的相分离程度很大 ,而HTBN基PU的相分离程度小 .这可能归因于HTBS软段的极性低 ,不能与硬段形成氢键 ,而HTBN软段中的腈基具有很强的极性 ,且可以与硬段形成氢键作用 ,增加了软硬段间的相容性 ,相分离程度明显降低 .AFM表明HTBN PU随着硬段含量提高 ,表面粗糙度增大 ,由软段为连续相逐渐过渡到双连续结构 .在硬段含量 6 3%时 ,HTBN和HTPB基PU均呈双连续结构 ,而HTBS PU中硬段为连续相 .HTBN PU软段的相区尺寸在1 2nm左右 ,表面粗糙度较大 ,HPBS PU软段的相区尺寸在 1 1nm左右 ,表面粗糙度最小 ,HTPB PU存在 1 4nm和 5 0nm大小不等的软段相区尺寸 .力学性能表明 ,在软段中引入苯乙烯和丙烯腈结构 ,可使聚氨酯抗张强度分别提高 1 5和 2倍 ,模量和断裂伸长率也明显提高