Surface composition and property of film prepared with aqueous dispersion of polyurethaneurea-acrylate including fluorinated block copolymer

The aqueous dispersion of polyurethaneurea-acrylate (PUA) including small amount of fluorinated block copolymers containing carboxyl groups (PATF), which can be dissolved in water, was used to make films and the surface properties of these films were examined. The experimental data show that the modified PUA film exhibits a hydrophobic surface property, although the original surface of PUA film is hydrophilic. The surface composition of the modified PUA film was measured by ATR and XPS. The results indicate that there is a concentration gradient of the fluorine groups along the lines of thickness of the modified film and towards the outmost surface layer, resulting from the migration of fluorinated blocks to the air side surface of the modified PUA film during the film formation process. However, the PUA film can not be modified effectively by adding the sodium salt of PATF, since the urethane groups in the system are easy to occupy on the surface of the film.     

Solid state extrusion of thermoplastic elastomers 4

A solid state extrusion technique is applied as to produce oriented block copoly(ether ester) under various physical conditions. The morphology of the extruded samples is characterized in relation to the extrusion parameters and hard segment compositions of the polymer, using thermal analysis and X-ray methods. The lateral dimensions of the crystalline domains are found to be approximately 150 Å depending on the extrusion conditions. The statistics of the long range periodicity of the structure along the extrusion direction is in agreement with a one-dimensional two phase model, the crystalline portion of which does not vary much in thickness (35 – 45 Å). The unexpected increase in the long period and the thermal shrinkage suggest the existence of strained interlamellar amorphous chains (tie molecules). The observed variations in tensile properties are interpreted under the assumption that both the number of such tie molecules and their fully extended lengths are determined by the hard segment composition and the extrusion conditions. It is also argued that the increase in the glass transition temperature is not only a function of the composition of hard segments in the amorphous phase but also of the number of strained tie molecules.Herrn Dr. Dr. h. c. H. Hellmann zum 70. Geburtstag gewidmet.Part 3 cf. lit [11]     

用含偶氮基的聚苯乙烯大分子引发剂合成两亲性嵌段共聚物

采用含偶氮基的聚苯乙烯预聚物（ＰＳ ＡＣＰＣ）作为引发剂，合成了苯乙烯（Ｓｔ）分别与甲基丙烯酸（ＭＡＡ）、甲基丙烯酸（β 羟丙酯）（ＨＰＭＡ）的嵌段共聚物，考察了ＰＳ ＡＣＰＣ引发第二单体的聚合反应行为，以及影响第二单体转化率和均聚物含量、共聚物组成的因素．用溶解性、凝胶渗透色谱（ＧＰＣ）、红外光谱（ＩＲ）、核磁共振（ＮＭＲ）、动态接触角（ＤＣＡ）等表征了嵌段共聚物．     

聚己内酯聚醚嵌段共聚物和共混物的表面性质对其药物释放行为的影响

聚己内酯聚醚嵌段共聚物和共混物的表面性质对其药物释放行为的影响王卫华，贝建中，王智峰，王身国（中国科学院化学研究所北京１０００８０）关键词聚己内酯聚醚嵌段共聚物，共混物，电子能谱，表面性质，药物释放行为聚己内醋（ＰＣＬ）具有优良的药物通透性和生物相容...     

聚酯-聚酯多嵌段共聚物的合成及其动态力学性能

聚酯-聚醚多嵌段共聚物的动态力学性能谱上有两个T_8,不宜做阻尼材料。本文报道聚对苯二甲酸乙二醇酯(PET)-端羟基聚己二酸乙二醇酯(PEA)共聚物(简称嵌段共聚酯),比聚醚-聚酯多嵌段共聚物有更好的相容性。我们研究了PEA的分子量,间苯二甲酸的用量对嵌段共聚酯的结晶度,以及结晶度对嵌段共聚酯的动态力学性能的影响。     

Monolayer films of PS-b-PEO diblock copolymers at the air/water- and an oil/water-interface

 Amphiphilic diblock copolymers consisting of a hydrophobic polystyrene block (PS) and a hydrophilic poly(ethylene oxide) block (PEO) with block sizes of 1000 or 3000 g/mol for both blocks were studied at the air/water and toluene/water interface. Measurements of the film pressure π of spread monolayers at the water surface reveal two limiting regimes of the π−a _m isotherms, in which the mean molecular area a _m is determined either by the size of the hydrophilic or the hydrophobic blocks of the PS-PEO molecules. The interfacial activity of the block copolymers at the toluene/water interface was studied by measuring the interfacial tension σ over a wide range of concentrations. Pronounced differences in the temperature dependence of the interfacial tension were observed, depending mostly on the block length of the hydrophilic PEO block. From the temperature dependence of σ it is inferred that for the block copolymers with the PEO block size of 3000 g/mol the phase inversion temperature (PIT) is well above 60 °C while for those with a PEO block size of 1000 g/mol the PIT is below or near 25 °C in the toluene/water system. Received: 5 February 1998 Accepted: 16 February 1998     

Cis-coordination of the chromate anions in helical Co/Ni block-type polymeric systems. Structural and spectroscopic characteristics of catena(μ-CrO4-O,O′)[Co(HIm)3H2O] and catena(μ-CrO4-O,O′)[Co0.43Ni0.57(HIm)3H2O]

Two polymeric complexes: catena(μ-CrO₄-O,O′)[Co(HIm)₃H₂O] (1) and catena(μ-CrO₄-O,O′)[Co_0.43Ni_0.57(HIm)₃H₂O] (2) (where HIm=imidazole) with a cis-bridging coordination mode of the CrO₄ ²⁻ anion have been synthesized and characterized by X-ray and spectroscopic methods. These crystals were isolated from nine systems of varying reagent molar ratios and three excluding anions: Cl⁻, NO₃ ⁻ and SO₄ ²⁻ exclusively as mer [M(HIm)₃O₃]-type isomers. The unit cell of these isostructural complexes (monoclinic crystal system P2₁ /n) contains two independent helixes, left- and right handed, stabilized by intrahelical and interhelical hydrogen bonding and π–π interaction between pairs of the imidazole rings from neighbouring helixes. The Raman spectra at 77 K of 1 and 2 deconvoluted into lorentzian components revealed the block-type polymeric structure of the complexes. Moreover, the solution studies at millimolar concentrations of 1 and 2 indicated their complete decomposition in water. Four K electronic spectral analysis of the crystals (band deconvolution into gaussian components) enhanced with the data obtained in the polarized light allowed for assignment of the bands to the respective d–d transition (D_4h symmetry). It was found that the metallic centres are independently absorbing species, which supports the suggestion of a block-type structure of the polymers. The respective crystal field parameters for Co and Ni were calculated.     

Hydrogenated polybutadiene–polymethyl methacrylate (HPB–PMMA) block copolymer. I. Synthesis of polybutadiene–polymethyl methacrylate (PB–PMMA) block copolymer

To get hydrogenated polybutadiene-polymethyl methacrylate (HPB-b-PMMA) block copolymer to be used as a compatibilizer for blends of polyolefin/polar polymer, PB-b-PMMA was synthesized by anionic-free radical mechanism transformation polymerization. Selective extraction, gradient elution thin layer chromatography, and oil-oil emulsion separation techniques were tried to attempt to separate the copolymerization products. Hydrogenation of the PB sequence in PB-b-PMMA yielded HPB-b-PMMA. The compatibilizing function of PB-b-PMMA was shown in blending experiments. © 1993 John Wiley & Sons, Inc.     

Dielectric relaxation of poly(ester-ether-carbonate) multiblock terpolymers

The dielectric properties of a series of poly(ester-ether-carbonate) multiblock terpolymers have been investigated as a function of ether and carbonate composition in the frequency range of 10³–10⁶ Hz. The degree of polymerization of the samples was determined by viscosimetry measurements. The weight fraction, degree of crystallinity, and melting temperatures were characterized by means of x-ray diffraction and DSC methods. Dielectric behavior has been discussed in terms of Havriliak-Negami formulation. The variation of the dielectric properties with temperature has been associated with two relaxation processes: a) the -relaxation process observed at low temperature, which is associated to local motion of polar groups attached to both the soft and the hard segments, and b) the process assigned to long-range molecular motions above the glass transition temperature.     

矩形窗正交时频空检测算法

针对正交时频空(Orthogonal Time Frequency Space, OTFS)调制系统采用矩形窗函数时,信道矩阵结构复杂导致的鲁棒性差的问题,提出了一种基于时域处理和酉近似消息传递的检测算法。该算法首先添加循环前缀,将时域信道转换为分块对角矩阵;然后应用酉变换和近似消息传递建立迭代检测算法。仿真结果表明,所提检测算法能够在不增加复杂度的条件下有效提升检测精度和鲁棒性,特别是存在信道编码的条件下表现出2 dB的性能增益,使得该算法更适用于杂散多径、高速移动等环境,具有较高的应用价值。