用可再生原料合成聚氨酯脲水分散液——成膜后的结构与性能研究

以不同组成的蓖麻油和二官能度聚醚多元醇 (GE 2 10 )等原料合成了聚氨酯脲 (PUU)水分散液 ,研究了蓖麻油 GE 2 10的组成对PUU膜结构与性能的影响 .结果表明 ,由GE 2 10合成的PUU虽软硬段间存在一定的相容性 ,但其中脲羰基的氢键化程度高 ,硬段形成较好的有序结构 ,导致PUU膜具有较高的拉伸强度及断裂伸长率 ,但弹性模量和硬度下降 .在蓖麻油合成的PUU中脲羰基的氢键化程度及硬段有序结构均受到化学交联结构的抑制 ,故PUU膜的拉伸强度和断裂伸长率降低 ,但弹性模量及硬度较高 .由蓖麻油与GE 2 10在一定的组成范围内合成的PUU膜 ,具有优良的综合平衡的力学性能 ,后者与材料的结构形态相符     

液态水几何构型的分子动力学模拟

利用ＭＣＹＬ势对液态水进行分子动力学模拟，以探求近程和远程相互作用及液体的有序结构对水分子几何构型的影响，并确定对液态中水分子几何构型起作用的主要范围。模拟给出的液态水中原子对径向分布函数和水分子键长键角的变化与实验值能较好地符合。研究结果表明，液态水分子几何构型除与氢键的形成有关外，还与液体的近程有序结构有很大关系。键长的变化对这种近程有序结构虽不敏感，但键角的变化则对此非常灵敏。液态中第二水合     

聚N,N-二乙基丙烯酰胺低聚物水溶液的分子动力学研究

对50个单元构成的聚N,N-二乙基丙烯酰胺(PDEA)低聚物的水溶液体系进行了分子动力学的研究,分别模拟了300 K时的伸展链、310 K时的伸展链以及紧缩链与水构成的体系,对溶液中PDEA周围溶剂水分子的分布情况以及水分子形成氢键的情况进行了统计,结果表明在PDEA周围的水产生了比本体水更有序的结构,形成了更多的氢键,这种有序结构维持到第二水合层甚至更远.发生相分离后,PDEA与水分子形成的氢键大部分未被破坏,水合层中每个水分子形成的氢键数也没有明显变化,但水合层(形成有序结构的水分子)内水分子数目的减少使得总的氢键数目减少,从而造成体系能量增加及熵增加.同时还研究了聚合物及水分子的自扩散系数,表明PDEA影响周围水分子结构的同时,对水的动力学性质也产生了很大影响.     

特殊缔合体系TFE水溶液分子动力学模拟

三氟乙醇(TFE)水溶液是一类特殊的缔合体系. 采用分子动力学模拟方法结合核磁共振化学位移研究了TFE水溶液体系全浓度范围的氢键网络, 并对动力学模拟结果和核磁共振化学位移进行了比较. 从径向分布函数(RDF)发现, TFE水溶液中存在着强氢键, 而体系中的C—H…O弱相互作用较为明显, 也不能忽略. 氢键网络分析发现TFE 水溶液体系的氢键大致分为以下三个区域: 在水富集区域, 水分子倾向于自身缔合形成稳定的簇结构, 随着TFE 浓度的增加, 水的有序结构受到破坏, 水分子和TFE分子发生交叉缔合作用形成氢键; 在TFE富集区域, 水分子较少, TFE分子自身通过氢键形成多缔体结构. 此外, 分子动力学统计的平均氢键数的变化和文献报导的核磁共振化学位移变化趋势相同, 实验和理论的结果吻合较好.     

温度对液态水结构的影响：中子及X射线散射研究

采用中子散射和X射线散射研究了液态水在298～373 K温度范围内的结构,通过偏径向分布函数(PDF)、配位数分布(CN)、角分布(ADF)及空间密度分布(SDF)等讨论了温度对液态水结构的影响。整体来看,液态水具有"不规则四面体"氢键网络的短程有序结构,该有序度可延续到第三水合层。液态水分子的第一水合层中,围绕中心水分子约有4.8个水分子,然而其中仅有约3.3个水分子与中心水分子通过氢键相键合,约1/3进入到第一水合层的水分子并未与中心水分子直接键合,也正是这些间隙水分子的存在加剧了液态水结构的复杂性。温度对液态水的有序度存在一定的影响,在298～373 K的有限温度变化范围内,温度对液态水中氢键的键长、键角分布及第一水合层SDF的影响不大。从298K升温到373K,O(W)-O(W)距离仅增加0.03?,氢键数目也仅有微小减少,温度对第二和第三水合层的影响则要显著很多。     

核—壳结构聚丙烯酸酯—聚氨酯微乳液膜的相行为

用动态力学、红外光谱和差热分析方法研究了非交联核－壳结构聚丙烯酸酯－聚氨酯（ＰＡＣ－ＰＵ）微乳液膜的相行为．结果表明：核壳间的氢键增强了壳层软硬段间的相分离，同时破坏了硬段相中的短程有序结构，但增强了核壳相容性     

CdS量子点与CdSe量子点间荧光共振能量转移研究

在有机相中合成了不同尺寸的CdS和CdSe量子点, 并利用Langmuir-Blodgett (LB)技术将相同尺寸的CdS和CdSe量子点组装成多层复合纳米有序结构. 采用荧光光谱研究了CdS和CdSe量子点在混合体系和多层复合纳米有序结构状态下的荧光共振能量转移(Fluorescence resonance energy transfer, FRET). 我们观察到CdS和CdSe量子点混合溶液与当溶剂挥发形成固态膜中, CdS量子点的荧光强度较溶液状态下强烈猝灭, 表明当颗粒间距离减小时CdS和CdSe量子点间产生较高效率的荧光共振能量转移. 在多层复合纳米有序结构中, 随着给体CdS量子点层数的增加, 单层受体CdSe量子点的荧光逐步增强, 这表明层间纵向能量转移率随给体层数的增加而提高.     

α-生育酚在模型生物膜中的分子动力学模拟

用分子动力学方法模拟了280, 310和350 K下α-生育酚在二豆蔻酰磷脂酰胆碱、二豆蔻酰磷脂酰乙醇胺、二硬脂酰磷脂酰胆碱和二硬脂酰磷脂酰乙醇胺双层膜中的性质, 包括了空间位置、氢键、取向和动力学性质, 取得了如下的结论. 第一, 生育酚头部的羟基一般位于脂双层亲疏水界面的下方, 升高温度将促进羟基向膜双层的中心移动, 在350 K时观察到了在上下两个单层间的翻转. 第二, 生育酚主要与磷脂的酯基形成氢键, 几乎不与磷脂酰乙醇胺的氨基形成氢键; 比较生育酚与磷脂酰胆碱和乙醇胺形成的氢键后发现, 后者更稳定. 第三, 生育酚的头部在膜中取向多变, 与膜的法线夹角不固定, 尾部的构象也很复杂. 第四, 在温度较低时, 生育酚的侧向扩散系数与磷脂的相当, 但在350 K时其扩散速度明显加快; 在垂直方向生育酚的扩散速度很慢.     

磷脂酸Langmuir-Blodgett膜分子结构的原子力显微术研究——分子排列有序性,分子间氢键作用,超分子结构以及晶格结构转变

利用原子力显微镜(AFM)研究了二棕榈酰磷脂酸(DPPA)的单层,双层和三层Langmuir-Blodgett膜的分子排列结构,发现相邻的(2～6个)DPPA分子的极性头磷酸基团通过分子间氢键形成局域超分子结构.分子分辨的AFM图象表明,DP-PA LB膜中分子排列具有长程的取向和位置有序.DPPA分子的晶格排列随着LB膜层数的增加由单层和双层的六方晶格转变成三层的正交(四方)晶格.探讨了不同的pH下的DPPA极性头磷酸基团的分子间氢键作用及其对膜分子有序排列以及云母基片对DPPALB膜中分子排列的晶格结构的影响.     

二氟尼柳/水滑石插层组装结构、氢键及水合特性的分子动力学模拟

采用分子动力学方法模拟二氟尼柳插层水滑石(DIF/LDHs)的超分子结构, 研究复合材料主客体间形成的氢键以及水合膨胀特性.结果表明, 当水分子总数与DIF分子总数之比Nw≤3时, 层间距dc保持基本恒定, 约1.80 nm; 当Nw≥4时, 层间距逐渐增大, 且符合dc=1.2611Nw+13.63线性方程. 随着水分子个数增加, 水合能驻UH逐渐增大. 当Nw≤16时, 由于⊿UH<-41.84 kJ·mol-1, LDHs-DIF可以持续吸收水, 从而使材料层间距不断膨胀. 但当Nw≥24时, ⊿UH>-41.84 kJ·mol-1, 此时LDHs-DIF层间不能再进一步水合, 因此LDHs-DIF在水环境中膨胀具有一定的限度. 水滑石层间存在复杂的氢键网络. DIF/LDHs水合过程中, 水分子首先同步与层板和阴离子构成氢键; 当阴离子趋于饱和后, 水分子继续与层板形成氢键, 并逐步发生L-W型氢键取代L-A型氢键, 驱使阴离子向层间中央移动, 与层板发生隔离; 最后水分子在水滑石羟基表面形成有序结构化水层.     

粘度法研究壳聚糖与两性聚氨酯胶束间的相互作用

通过粘度法考察了壳聚糖(CS)在盐酸水溶液中与表面带有正电荷的两性聚氨酯(APU)胶束的相互作用，并研究了小分子盐浓度、pH及不同混合方式对复合体系粘度的影响．结果表明：在壳聚糖／APU盐酸混合体系中，较高浓度下APU胶束与壳聚糖分子间的静电斥力作用导致壳聚糖大分子链的伸展，使体系粘度提高，同时降低了壳聚糖溶液对电解质、pH的敏感性；不同混合过程导致壳聚糖大分子构像及其与APU组装、复合形态有很大差别，使混合体系流变性表现出明显的不同．     

Phase transition properties of vanadium oxide films deposited by polymer-assisted deposition

Vanadium dioxide (VO₂) films were synthesized on mica substrates by a polymer-assisted deposition method, followed by rapid annealing with different annealing temperatures. The crystalline structure and morphology of the films were investigated by XRD and FE-SEM, and their phase transition properties were studied by in situ FT-IR. The results indicated that the annealing temperature affected the crystalline structure and morphology of the films remarkably, which then resulted in varied phase transition properties. In particular, the films annealed at higher temperature showed more polycrystalline structure, increased particle size and reduced phase transition intensity. But the films exhibited the similar hysteresis temperature width with increasing annealing temperature.     

Stabilized micelles of amphoteric polyurethane formed by thermoresponsive micellization in HCl aqueous solution

The thermoresponsive micellization behavior of amphoteric polyurethane (APU) was studied in HCl aqueous solution (pH 2.0) through light scattering, transmission electron microscopy, and fluorescent measurement. When APU concentration is high enough, nonreversible assembly of macromolecules can be observed with temperature decreasing from 25 to 4 degrees C. However, micelles reaching equilibrium at 4 degrees C can self-assemble reversibly in the temperature range of 4-55 degrees C. According to our research, we found it is the temperature sensitivity of the poly(propylene oxide) (PPO) segments that leads to the reassembly of APU at lower temperature. We proposed that core-shell-corona micelles ultimately form with hydrophobic core, PPO shell, and hydrophilic corona when temperature increases from 4 to 25 degrees C. This structure is very stable and does not change at higher temperatures (25-55 degrees C). That provides a new way to obtain stable micelles with small size and narrow size distribution at higher concentration of APU.     

Novel regular network polyester films from benezenetricarboxylic acids and glycols

Novel regular network polyester films were prepared from benzenetricarboxylic acids of trimesic (Y) and trimellitic (Z) acids, and glycols of ethylene (2G), tetramethylene (4G), and hexamethylene (6G) glycols. Prepolymers prepared by melt polycondensation for a short period within 1 h were cast from a DMF solution and successively post-polymerized at various temperatures and times to form a network. The resultant films were transparent, flexible, and insoluble in any solvents. Distortion temperature measured by a penetration mode of thermomechanical analysis (TMA) increased with increasing post polymerization time and temperature, and leveled out at 222, 168, 125 and 75°C, for the 2GY, 2GZ, 4GY, and 6GY films, respectively. Temperatures close to 400°C at which the probe had completely penetrated corresponded to the thermal decomposition temperature of these films. Two broad but strong peaks in the x-ray diffraction curves appears for the 2GY, 4GY, and 6GY, suggesting the formation of some ordered supramolecular structure owing to the regular network formed by symmetrical trimesic acid moiety, and the intensity of diffraction peaks became higher with increasing length of the methylene chain of the glycol monomer. Densities of the 2GY and 2GZ films decreased with increasing post-polymerization time and temperature. Tensile strength and Young's modulus increased and elongation decreased with increasing network formation. These tensile properties was affected by the chemical structure of the network films.     

Preparation and properties of waterborne polyurethaneurea consisting of fluorinated siloxane units

A series of polyurethaneurea (PUU) aqueous dispersions were prepared via a prepolymer process from polyester polyol, α,ω‐dihydroxypoly[(3,3,3‐trifluoropropyl) methylsiloxane] (PTFPMS), dimethylolpropionic acid, isophorone diisocyanate, and ethylenediamine. These anionic‐type aqueous dispersions were stable at the ambient temperature for more than 6 months, with particle sizes ranging from 69 to 127 nm. For these aqueous dispersions, the surface tension decreased with increasing PTFPMS content, but the particle size increased with a maximum value. The film prepared from the PUU aqueous dispersion consisting of 5 wt % PTFPMS (APU‐FS‐5) exhibited excellent waterproof performance. Furthermore, the tensile strength of the APU‐FS‐5 film increased nearly 3 times compared with that of the PUU film without PTFPMS, whereas the elongation at break only decreased a little; this indicated that the water‐resistant and mechanical properties could be enhanced markedly and simultaneously for the PUU films containing both silicon and fluorine groups. The experimental results showed a high degree of hydrogen bonding for urea groups and an increased microphase‐separation degree between the hard and soft segments in the PTFPMS‐modified system, which resulted in the excellent mechanical properties of these films. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3365–3373, 2006     

脂肪族水性聚氨酯的力学性能研究

考察了软段的种类、分子量大小、混合软段的组成对产物力学性能的影响作用。同时还研究了二羟甲基丙酸(DMPA)用量以及中和剂的影响作用．实验结果表明。软段结构对脂肪族水性聚氨酯成膜的力学性能影响很大，聚酯型产物具有较高的模量和拉伸强度。聚醚型产物则具有较高的伸长率．混合软段对产物力学性能的影响较为复杂，随着软段中聚醚含量的升高，产物的硬度和模量均大幅度下降，但拉伸强度和伸长率的变化并不是一个线性关系．产物的模量随软段分子量的提高而降低，但伸长率和拉伸强度却有所提高．当DMPA用量较高时。产物的模量和拉伸强度均较高：当DMPA用量较低时，产物则具有较高的伸长率．中和剂的种类对产物力学性能的影响明显，当以NaOH为中和剂时，产物具有较高的硬度、模量、拉伸强度：以三乙胺为中和剂时，产物具有较高的伸长率．     

Carbon dots embedded nanofiber films: Large-scale fabrication and enhanced mechanical properties

Valuable application prospects and large-scale production technologies are powerful driving forces for the development of materials science. Carbon dots(CDs) are a kind of promising carbon-based fluorescent nanomaterials, which possess wide application prospects based and even beyond the fluorescence properties. Herein, we report the fast and high-yield synthesis of CDs and the large-scale preparation of fluorescent nanofiber films with enhanced mechanical properties. CDs were prepared from magn...     

Morphological effect on spectral property of poly(9,9-dihexylfluorene-alt-2,5-dihexyloxybenzene) films

In this study the optical property and film morphology of a conjugated polymer, poly(9,9-dihexylfluorene-alt-2,5-dihexyloxybenzene) (PF6OC6), are investigated. It is found that the intensity of the 0-1 emission relative to the 0-0 emission in the PL spectra and the full width at the half-maximum (fwhm) of PL spectra of the PF6OC6 films decrease firstly and then increase with increasing the annealing temperature. The polymer films also exhibit different morphological features after annealing at different temperatures. The optical and morphological results suggest that the vibronic structure of PF6OC6 is closely related to the film morphology, and its formation is enhanced in the amorphous (or less ordered) films and inhibited in the ordered films.     

Temperature-assisted photochemical construction of CdS-based ordered porous films with photocatalytic activities on solution surfaces

Taking a colloidal monolayer floating on the surface of a precursor solution as template, free-standing CdS/Cd composites and pure CdS (CdS-based) ordered porous films had been prepared by a temperature-assisted photochemical strategy. After irradiation with UV-light and heat treatment, the films formed hemi-spherical pores due to the preferable deposition of CdS and Cd onto the PS spheres during the photochemical and interfacial reactions. When the temperature increased from 15 to 60°C, the air/water interface gradually changed into a vapor/water interface on the surface of the solution, resulting in variations of the final compositions. The optical properties of the films were hence changed. Because of the free-standing characteristic, the ordered porous films were first transferred on surface of polluted solutions as photocatalysts, which was a new mode in application of photocatalysts. The photocatalytic activities of films showed regular variations with the compositions in photodegradation of Rhodamine B. This method provides a simple route for tuning the properties of porous films through control of its composition and a flexible application of films on any surface.     

核壳结构三维有序水凝胶的制备

随着科学技术的发展 ,人们不断地寻求具有新特性、新功能的高分子材料 .聚合物凝胶作为一种智能高分子材料 ,受到极大的关注[1,2 ] .聚合物凝胶具有外场响应特性 ,其体积可随外界环境如溶剂、温度、电场、磁场、ｐＨ值、化学物质或光照等条件的改变而变化 ,因而在药物可控释放、吸附分离及传感器等方面具有潜在应用价值 .对聚合物凝胶进行图案化处理 ,使之成为有序结构 ,大大拓宽了凝胶的应用范围 .Ｈｕ等[3 ,4 ] 首先报道了环境响应水凝胶表面图案的调控技术 ,图案的特征尺寸在微米级 ,此类凝胶作为光栅 ,在光纤、传感器和光通信中具有潜在…