无皂乳液聚合制备高浓度单分散聚(苯乙烯-甲基丙烯酸甲酯)胶体粒子

通过添加聚乙烯醇和丙酮，找到了一种无皂乳液聚合制备高浓度单分散苯乙烯－甲基丙烯酸甲酯共聚胶体粒子的新途径，粒子半径达纳米数量级，体系的固含量大于50％，研究了聚乙烯醇和丙酮对反应过程，胶乳粒子大小的影响，结果表明聚乙烯醇和丙酮对高浓度无皂纳米胶乳粒子的形成与稳定起重要作用。     

电阻型湿敏材料的核磁共振研究

利用核磁共振氢谱研究了不同湿度和温度条件下聚乙烯亚胺，聚乙烯铵盐及环氧乙烷３种电阻型湿敏材料，通过化学位移变化分析了感湿机理，指出３种材料中的活泼氢和水作用后能形成新的活泼氢，新旧活泼氢可发生快速交换现象，并产生带电离子，因而材料的电阻值随湿度的增加而大幅度地降低。     

交联方法对交联聚乙烯结晶行为的影响

研究了硅烷交联聚乙烯和过氧化物交联聚乙烯由于结晶和交联的顺序不同而造成的结晶行为的差异，交联密度相同时，过氧化物交联聚乙烯的结晶度和熔点明显低于硅烷交联聚乙烯，交联聚烯非等温结晶动力学表明：交联前后聚乙烯的Ａｖｒａｍｉ指数ｎ基本不变，交联后，半结晶期ｔ１／２延长、结晶速率常数ＺＣ下降，其中过氧化物交联聚乙烯的变化幅度大于硅烷交联聚乙烯。     

聚乙烯在石墨表面结晶的分子动力学模拟

采用分子动力学方法模拟了聚乙烯在石墨(001)表面的吸附和结晶过程;直观的给出了聚乙烯链被石墨(001)面吸附并诱导形成有序的片层晶体的过程;发现结晶温度对得到的有序结构中的聚乙烯链相对石墨表面的特定取向有影响(300 K和600 K时的取向方向不同);表面覆盖率影响聚乙烯吸附层的厚度,对取向的方向无影响.     

粉状白钨酸研究（XIX）：聚乙烯醇水溶液中十聚钨酸的稳定性 …

粉状白钨酸在含聚乙烯的水溶液中能够形成十聚钨酸，通过紫外－可见吸收光谱，顺磁共振，ｐＨ滴定及五价钨的测定十聚钨酸的稳定性和光致变色性质进行了研究，结果表明，十聚钨酸的还原程度与溶液的酸度有关，在较高的ｐＨ条件下形成单电子还原物种，而在较低的ｐＨ条件下则主要形成双电子还原物种。     

聚乙烯接枝香豆素衍生物作为多功能助剂的应用探究

以商品化乙烯醋酸乙烯酯共聚物(EVA)为原料，通过Mitsunobu衍生化反应合成了以香豆素为功能侧基的多功能聚乙烯.香豆素及其衍生物是一种多功能性的化合物，拥有抗菌、抗癌、光敏性、抗紫外线吸收以及抗氧化等特性，引入聚乙烯骨架可以赋予聚乙烯相似特性.以红外和核磁表征手段对聚乙烯基香豆素衍生物结构进行了确认.将其用作聚乙烯的加工助剂，不仅能够赋予聚乙烯基底抗菌和抗氧化的特性，而且还能够起到抗紫外线老化的效果；与此同时，相比于商用抗紫外线吸收剂，其不仅具有更为优越的抗紫外线老化性能，而且还能够有效避免助剂的迁移.     

α-萘基丁二亚胺氯化镍/MAO制备双(宽)峰聚乙烯

合成了一种新型α 二亚胺镍配合物———α 萘基丁二亚胺氯化镍 ,此配合物作为催化剂在MAO的活化下催化乙烯聚合得到支化聚乙烯 ,聚合活性高达 7 18× 10 5gPE molNi·h ,1 3C NMR、FTIR测试结果表明制备的聚乙烯含有末端双键 ;GPC结果表明所制备的聚乙烯分子量呈双 (宽 )峰分布 ,其原因有两个 ,一是此催化剂能产生分子量较低的α 烯烃 ,在聚合过程中一部分α 烯烃会“就地”与乙烯原位共聚形成分子量较高的聚合物 ,二是此催化剂存在立体异构体 ,而不同异构体在MAO活化下形成的活性中心的配位环境不同 ,因而得到的聚乙烯的分子量也不同 .研究了聚合温度、聚合压力、铝镍摩尔比 (nAl nNi)对催化活性、聚乙烯分子量、支化度的影响 .聚乙烯的分子量随聚合温度的升高而下降 ,支化度增大 ,熔点则降低 .     

嵌段共聚物PVCH-b-PE-b-PVCH的多重结晶行为

通过采用差示扫描量热仪(DSC)主要研究了结晶-非晶嵌段共聚物聚乙烯基环己烷-b-聚乙烯-聚乙烯基环己烷(PVCH-b-PE-b-PVCH)溶液结晶样品的熔融与非等温再结晶过程.探讨了溶液结晶样品中微相分离结构的形成对嵌段共聚物受限结晶的影响,并发现样品在熔融后的非等温结晶过程中出现了多重结晶峰.通过对嵌段共聚物有序、...     

在聚乙烯吡咯啉酮—盐—水的液—固萃了以体系中溴络阴离子的萃取…

本文研究了在聚乙烯吡咯啉酮－盐－水度的液－固萃取体系中，Ａｕ（Ⅲ）、Ｂｉ（Ⅲ）、Ｚｎ（Ⅱ）和Ｆｅ（Ⅲ）与Ｂｒ＾－形成的络阴郭，在两相间的分配行为。     

聚合所得初生聚乙烯的晶型

聚合所得初生聚乙烯的晶型伍青，张启兴，卢泽俭，王海华，欧阳巍，林尚安，张光华（中山大学高分子研究所，广州，５１０２７５）（中国科学院广州化学研究所）关键词聚乙烯，结晶，单斜晶，颗粒形态热力学稳定的聚乙烯晶型为正交晶系［１］．当聚乙烯受一定应力作用时如...     

Pressure-induced hexagonal phase in a ternary microemulsion system composed of a nonionic surfactant, water, and oil

The pressure-induced phase transition in a microemulsion, consisting of pentaethylene glycol mono-n-dodecyl ether, water, and n-octane, was investigated by means of small-angle neutron scattering. A pressure-induced phase transition from a lamellar structure to a hexagonal structure was observed. The temperature-pressure phase boundary shows a positive slope with dTdP approximately 0.09 KMPa. The structure unit of the high-pressure hexagonal phase was an oil-in-water cylinder with the membrane thickness of 15.5 A, identical to the low-temperature hexagonal phase. Pressurizing was found to have the same effect by decreasing temperature. This behavior was satisfactorily explained with the pressure dependence of the spontaneous curvature of surfactant membranes. That is, the volume change of surfactant tails plays a dominant role in the structure change of the microemulsion with applying pressure.     

Diffraction techniques for nonlamellar phases of phospholipids

A neutron diffraction method applicable to nonlamellar phases of substrate-supported lipid membranes is described and validated. When prepared on a flat substrate, the resulting nonlamellar phases have layered symmetry which provides some advantages over powder diffraction for detailed structure determination. This approach recently led to the detection of a rhombohedral phase and a distorted hexagonal phase of lipids. Here the determination of intensity and phase information for such phases is demonstrated by application to the hexagonal phase of diphytanoyl phosphatidylcholine (DPhPC). The hexagonal symmetry is used to verify the data reduction procedure for the intensities of the diffraction peaks. Diffraction intensities measured while varying the D2O/H2O ratio in the relative humidity was used to solve the phase problem. The neutron scattering length density distribution of the hexagonal phase was constructed and analyzed to elucidate the packing of the lipid molecules. The structure of DPhPC in the hexagonal phase is of interest in connection with its stalk structure in the rhombohedral phase. We also found that the incorporation of tetradecane into the DPhPC hexagonal phase is limited, similar to the case for dioleoyl phosphatidylethanolamine.     

SmBO3晶型转变的TEM表征与反射性能

三斜相SmBO3经过1200℃的高温煅烧会出现晶型转变现象,由三斜相全部转变为六方相。采用TEM表征了SmBO3粉体的晶型转变。SmBO3的晶型转变对激光反射率造成一定的影响,主要表现为:三斜相SmBO3对1.06μm激光的反射率较六方相SmBO3稍低,这是由于晶体结构的不同,晶胞常数发生变化,使得六方相SmBO3的吸收峰位置向长波方向红移了12 nm,吸收峰最低点的位置更偏离1.06μm;激光测试结果表明六方相SmBO3粉体对10.6μm激光的反射率要低于三斜相SmBO3粉体。     

Alpha-tocopherol-induced hexagonal HII phase formation in egg yolk phosphatidylcholine membranes

The effect of alpha-tocopherol and its acetate on the membrane structure of egg yolk phosphatidylcholine (egg PC) dispersions was investigated using phosphate-31 nuclear magnetic resonance (31P-NMR) and small-angle X-ray diffraction. The incorporation of alpha-tocopherol into egg PC dispersions induced a change in the 31P-NMR spectrum from a multilamellar bilayer line shape to a hexagonal HII one. The phase transition by alpha-tocopherol was also confirmed by small-angle X-ray diffraction analysis. The amount of hexagonal HII phase increased with increase in concentration of alpha-tocopherol. Egg PC dispersions containing a molar ratio of 0.8 of alpha-tocopherol gave a 31P-NMR spectrum of an approximately hexagonal HII type at 37 degrees C. The amount of hexagonal HII phase increased with increasing temperature, indicating that the alpha-tocopherol-induced phase transition is thermotropic and that the transition temperature of egg PC membranes from the lamellar to the hexagonal HII phase is lowered by alpha-tocopherol. The incorporation of alpha-tocopherol acetate did not induce any phase transition. This fact indicates that the hydroxyl group of alpha-tocopherol may play an important role in the hexagonal HII phase formation of egg PC dispersions.     

Mechanism of the transition between lamellar and gyroid phases formed by a diblock copolymer in aqueous solution

The mechanism of the transition from a lamellar phase to a gyroid phase in an aqueous solution of a diblock copolymer has been studied by time-resolved synchrotron small-angle X-ray scattering. The transition occurs via a metastable perforated lamellar structure. The perforations initially have liquidlike ordering before developing hexagonal packing. The transient phase of irregularly perforated layers is revealed by the development of diffuse scattering peaks, just below the Bragg peaks of the lamellar structure. The diffuse scattering is modeled by Monte Carlo simulations of perforated layers. Following the formation of perforations, Bragg peaks characteristic of a hexagonal structure signal an ordering into a hexagonal lattice (with the concomitant loss of diffuse scattering). Computer simulations based on a dynamic density functional model reproduce these features. The hexagonal perforated lamellar phase is rapidly replaced by the gyroid phase. The domain spacing of the gyroid phase is larger than that of the perforated lamellar structure. The perforated lamellar and gyroid phases coexist for a defined period. The reverse transition from gyroid to lamellae occurs directly, with no transient or metastable intermediates.     

Self-assembly of a hexagonal phase of wormlike micelles containing metal nanoclusters

Stable nanoclusters (approximately 2 nm in diameter) of copper, silver, gold, palladium, and ruthenium coated with hydrophobic coronas are easily trapped in self-assembled "soft crystal" hexagonal phase gels made of water and surfactants. The system's crystal structure and phase behavior are studied in detail. A partial phase diagram showing the hexagonal phase region for the water/SDS/toluene region is presented. High-energy X-ray scattering and cross-polarized optical microscopy experiments show that the clusters are tightly confined within the tubes. The thermal gel-fluid transitions of the hexagonal phase are investigated, and it is shown that the hexagonal phase can melt and recrystallize repeatedly. The melt/gel cycles enable easy trapping of various metal clusters in pre-prepared hexagonal phases. In contrast to spherical micelles, the hexagonal phase doped with metal clusters can grow without limit, basically up to the container walls (Ru-doped soft crystals grew to 0.5 mm over 2 months, forming wormlike tubes that are more than 50 microm long but only 7-10 nm in diameter).     

混合超分子液晶模板法合成六方介孔相含钛氧化硅

采用混合十六烷基三甲基溴化铵（CTAB）与不同碳链的脂肪胺（CnNH2n＋3, n=8,10,12,14,16）作模板,在四甲基氢氧化胺为碱源的条件下,合成了具有六方介孔结构的含钛氧化硅Ti MCM 41分子筛材料. XRD和TEM测试表明所合成材料具有高度的长程有序结构,样品的N2吸附/脱附等温线表明,高度有序的Ti MCM 41材料展示了毛细凝聚的陡峭台阶和狭窄的介孔孔径分布.对反应物配比中Ti/Si比、脂肪胺碳链长度n对六方介孔相结构的影响进行了研究,实验发现当Ti/Si< 0.15和n< 16时,均可获得具有六方介孔结构的含钛氧化硅Ti MCM 41;而当Ti/Si≥0.15或n >16时,产物将分别发生从六方向无定形态或从六方向层状介孔相结构的转移,从混合表面活性剂的堆积参数对这种相转移现象进行了分析.     

Dissipative particle dynamics simulation of phase behavior of aerosol OT/water system

The phase behaviors of the binary mixture of an anionic surfactant aerosol OT (AOT) and water are investigated on a mesoscopic level using dissipative particle dynamics (DPD) computer simulations. With a simple surfactant model, various aggregation structures of AOT in water including the lamellar, viscous isotropic, and reverse hexagonal phases are obtained, which agree well with the experimental phase diagram. Special attention is given on the unusual lamellar regions. Water diffusivity shows much useful information to understand how the phase behaviors varied with concentration and temperature. It is proposed that the anomalous lamellar phenomena at intermediate AOT concentration (about 40%) are due to the formation of a defective structure, pseudoreversed hexagonal phase, which evidently decreases the water diffusivity. After increasing temperature above 328 K, the pseudoreversed hexagonal structure will be partly transformed to a normal lamellar phase structure and the system lamellar ordering is therefore enhanced.     

Order-order and order-disorder transitions in thin films of an amphiphilic liquid crystalline diblock copolymer

In this study, we quantitatively investigated the temperature-dependent phase transition behaviors of thin films of an interesting amphiphilic diblock copolymer, poly(ethylene oxide)-b-poly(11-[4-(4-butylphenylazo)phenoxy]undecyl methacrylate) (p(EO)-b-p(MAAZ)) and the resulting morphological structures by using synchrotron grazing incidence X-ray scattering (GIXS) and differential scanning calorimetry. The quantitative GIXS analysis showed that the diblock copolymer in the homogeneous, isotropic melt state undergoes phase-separation near 190 degrees C and then forms a body-centered cubic (BCC) structure of spherical p(EO) domains in the p(MAAZ) matrix, at which point the p(EO) domains and the p(MAAZ) matrix are both in amorphous, liquid states. The BCC structure of spherical p(EO) domains is converted to a hexagonal cylinder structure near 120 degrees C, which is induced by the transformation of the isotropic phase of the p(MAAZ) matrix to the smectic A phase, which is composed of a laterally ordered structure of p(MAAZ) blocks with fully extended side groups. The resulting hexagonal cylinder structure is very stable below 120 degrees C. This microscopic hexagonal cylinder structure is retained as the smectic A phase of the p(MAAZ) matrix undergoes further transitions to smectic C near 104 degrees C and to a smectic X phase near 76 degrees C, while the amorphous, liquid phase of the p(EO) cylinders undergoes crystallization near -15 degrees C. These complicated temperature-dependent disorder-order and order-order phase transitions in the films were found to take place reversibly during the heating run. A face-centered orthorhombic structure of p(EO) domains was also found during the heating run and is an intermediate structure in the hexagonal cylinder structure to BCC structure transformation. We use these structural analysis results to propose molecular structure models at various temperatures for thin films of the diblock polymer.     

层状和MSU结构的介孔纳米二氧化锆

在不添加任何结构稳定剂的条件下, 首次用固态反应结构导向法成功地合成了具有层状结构和MSU结构的介孔纳米二氧化锆. 研究发现, 通过有效地控制晶化条件, 二氧化锆的晶相、比表面和孔结构可以方便地得以调变. 晶相的转变由粒度大小控制, 并且构成无机骨架的相态不同, 合成样品的热稳定性存在差异. 结果显示, 介孔纳米二氧化锆的形成仍遵循超分子液晶模板机制, 且由碱锆摩尔比的大小控制介观相的转化, 低碱锆摩尔比条件下形成层状相, 而高碱锆摩尔比条件下为维持整个体系的低能稳定状态, 在电荷作用下形成反棒状胶束结构.