Materials Properties Derived from INSITE Metallocene Catalysts

Novel metallocene catalysts for the synthesis of ethylene/α‐olefin copolymers are reviewed here. The technology used—single‐site constrained geometry catalyst technology—is demonstrated to be useful for the preparation of a wide array of copolymers with unique materials properties, such as a high melt fracture resistance, as illustrated in the Figure.     

On the nature of multiple melting in poly(ethylene terephthalate) (PET) and its copolymers with cyclohexylene dimethylene terephthalate (PET/CT)

The multiple melting behavior of poly(ethylene terephthalate) (PET) homopolymers of different molecular weights and its cyclohexylene dimethylene (PET/CT) copolymers was studied by time-resolved simultaneous small-angle X-ray scattering/wide-angle X-ray scattering diffraction and differential scanning calorimetry techniques using a heating rate of 2 °C/min after isothermal crystallization at 200 °C for 30 min. The copolymer containing random incorporation of 1,4-cyclohexylene dimethylene terephthalate monomer cannot be cocrystallized with the ethylene terephthalate moiety. Isothermally crystallized samples were found to possess primary and secondary crystals. The statistical distribution of the primary crystals was found to be broad compared to that of the secondary crystals. During heating, the following mechanisms were assumed to explain the multiple melting behavior. The first endotherm is related to the non-reversing melting of very thin and defective secondary crystals formed during the late stages of crystallization. The second endotherm is associated with the melting of secondary crystals and partial melting of less stable primary crystals. The third endotherm is associated with the melting of the remaining stable primary crystals and the recrystallized crystals. Due to their large statistical distribution, the primary crystals melt in a broad temperature range, which includes both second and third melting endotherms. The amounts of secondary, primary and recrystallized crystals, being molten in each endotherm, are different in various PET samples, depending on variables such as isothermal crystallization temperature, time, molecular weight and co-monomer content.     

MA与AM二元共聚物的合成及其对泥浆性能的影响

采用水溶液聚合法合成了ＭＡ（马来酸酐）－ＡＭ（丙烯酰胺）二元共聚物。考察了ＭＡ与ＡＭ的摩尔比、单体浓度、引发剂用量、反应温度与时间对共聚产物在泥浆中的性能的影响。结果表明，ＡＭ／ＭＡ（摩尔比）大于１／１．５时，共聚物可作为增粘剂和降失水剂；ＡＭ／ＭＡ，小于１／１．５时，共聚物可作为稀释剂。     

羧甲基纤维素系列高分子表面活性剂与大庆原油的界面活性研究

研究了羧甲基纤维素系列高分子表面活性剂复配体系与大庆原油形成超低界面张力的条件,结果表明盐,醇的加入对高分子表面活性剂的界面活性影响不大;碱的加入能改善高分子表面活性剂分子在界面上的吸附,使界面张力大幅度下降,在适当配比下,高分子表面活性剂碱水溶液与原油可达到超代界面张力值（１０＾－３ｍＮ／ｍ）。     

超声辐照HEC／AEOn共聚物的合成及水溶液性能的研究

对三次采油用高分子表面活性剂的结构进行分子设计,采用简便、安全的超声波合成技术,获得了羟乙基纤维素（ ＨＥＣ）与脂肪醇聚氧乙烯醚活性大单体（ ＡＥＯｎ ,ｎ＝ ３ ,７,２０）共聚物,通过ＩＲ与ＤＳＣ表征了所制备的ＨＥＣ／ＡＥＯ 系列共聚物的结构,研究了共聚物水溶液的性能。结果表明,这种共聚物可以用作三次采油用高分子表面活性剂,其最低表面张力为２８ ．７ ｍ Ｎ／ｍ ,最低界面张力（５ ％ 大庆原油煤油溶液／０ ．５ ％ 共聚物水溶液） 为１ ．０６ｍ Ｎ／ｍ ,１ ％ 的共聚物水溶液表观粘度为２．９０ ｍＰａ·ｓ。     

国内油田用水溶性AMPS共聚物

介绍了２－丙烯酰胺基－２－甲基丙磺酸（ＡＭＰＳ）的合成以及油田用水溶性ＡＭＰＳ共聚物的研究与应用情况。水溶性ＡＭＳ共聚物热稳定性好,抗盐能力强,具有广泛开发前景的油田化学品。     

Amorphous Carbon Nanotubes with Tunable Properties via Template Wetting

Amorphous carbon nanotubes have been prepared by casting thin films of polyacrylonitrile (PAN) and polystyrene‐block‐polyacrylonitrile (PS‐b‐PAN) within a porous anodic aluminum oxide (AAO) membrane followed by pyrolysis. Raman and wide‐ angle X‐ray diffraction (WAXD) measurements indicate that the carbon nanotubes are of low crystallinity. The thickness of the carbon nanotube walls is controlled by either changing the concentration of the precursor solution or by using multiple casting and pyrolysis steps. When diblock copolymers of PS‐b‐PAN are used, it is found that nanopores are created within the nanotube walls after pyrolysis. The carbon nanotubes can be used to create carbon coated nanorods of polystyrene‐block‐polybutadiene (PS‐b‐PBD).     

Chiral Nematic Polymer Mixture Containing Crosslinker and Photosensitive Chiral Dopant: New Type of Materials with Tunable Photo‐Optical Properties

A cholesteric mixture based on a menthyl‐containing copolymer, photosensitive chiral dopant, mesogenic diacrylate, and photoinitiating agent has been prepared. The mixture shows a selective light reflection in the visible light spectral region. The action of UV irradiation (313 or 365 nm) on the planar‐oriented films generates the occurrence of two parallel processes: E/Z (i.e., cis–trans) photoisomerization of the chiral dopant and photopolymerization of the diacrylate. The first process leads to the untwisting of the cholesteric helix and shifts the selective light‐reflection maximum to the long‐wavelength spectral region, whereas the second process leads to the development of a polymer network that fixes the helical supramolecular structure. As a result of a simultaneous occurrence of the two above‐mentioned processes, the shift in the selective light‐reflection maximum is thermally irreversible, even though the Z/E isomerization of the chiral dopant itself can be reversed by annealing. On irradiation with visible light (>450 nm), the dopant experiences the E/Z isomerization but photopolymerization is absent because the photoinitiator shows no absorption in this spectral region. In this case, the shift in the selective light‐reflection maximum can be reversed to its initial value by annealing, whereby the original helix pitch is recovered. The kinetic features of helix untwisting at different temperatures and light wavelengths were studied. The experimental data obtained in this work allow one to conclude that the as‐prepared mixture presents a new multifunctional material with “tunable” photo‐optical properties and may be used for recording and storage of optical information.     

A Molecularly Imprinted Copolymer Designed for Enantioselective Recognition of Glutamic Acid

A newly designed molecularly imprinted polymer (MIP) material was developed and successfully used as recognition element to fabricate a capacitive sensor for enantioselective recognition of glutamic acid (Glu). The MIP with a well‐defined structure was synthesized on a gold electrode in one step by electrochemical copolymerization of o‐phenylenediamine (o‐PD) and dopamine (DA) in the presence of template molecule Glu. The resulting MIP material was characterized with a potentiostatic frequency scan method, cyclic voltammetry, capacitance measurements, atomic force microscopy, and X‐ray photoelectron spectroscopy. The structure and recognition behaviour of the copolymer film to template molecule depended on its composition. The optimal composition was at the o‐PD to DA molar ratio of 3:2. With a potentiostatic time scan method the copolymer displayed high enantioselectivity and sensitivity to the stereoselective rebinding of L ‐ or D ‐Glu to their corresponding artificial receptor due to the exact definition of the imprint cavity. The capacitance response of the sensor for L ‐Glu or D ‐Glu was proportional to their concentration in the range of 16.7 to 250 μM . The enantiometric selectivity coefficients for L ‐Glu and D ‐Glu imprinted films against their respective enantiomers are 24 and 15, respectively. The resulting MIP capacitive sensors showed good reproducibility, stability and repeatability. This strategy opened a convenient way for preparation of enantioselective MIPs and recognition of enantiotropic molecules.     

驱油用AST共聚物及其室内性能评定

本文简介了ＡＳＴ共聚物（丙烯酰胺、丙烯酸、甲基丙烯酸十二烷基酯三元共聚物）的合成，考察了实验室定型产品ＡＳＴ－２和ＡＳＴ－３作为驱油剂的使用性能：增稠性、耐盐性、耐温性、剪切安定性、表面活性、静态吸附、驱油效率、阻力系数和残余阻力系数等，并与国内外一些驱油聚合物进行了对比。