Preparation and properties of waterborne polyurethane–urea anionomers—influences of the type of neutralizing agent and chain extender

Waterborne polyurethane–urea anionomers were prepared by polyaddition reaction using isophorone diisocyanate (IPDI), poly(tetramethylene ether) glycol (PTMG, Mn=1000), dimethylolbutanoic acid (DMBA), and hydrazine monohydrate (HD), ethylene diamine (EDA), 1,4-butane diamine (BDA) as a chain extender, followed by neutralization of pendant COOH groups by NH₄OH/Cu(OH)₂ or triethylamine (TEA) as a neutralizing agent. The effects of the types of neutralizing agent such as NH₄OH/Cu(OH)₂ and TEA with various chain extenders on the properties of waterborne polyurethane–urea ionomers were investigated. Two loss modulus peaks for all samples are observed owing to the glass transition temperature of soft segments (Tg_s) and the glass transition temperature of hard segments (Tg_h). The conductivity, Tg_h, Tg, and tensile strength/modulus of TEA-based samples increased in the order of BDA>EDA>HD; however, those of NH₄OH/Cu(OH)₂-based samples increased in the order of HD>EDA>BDA. TEA-based film samples were found to have higher thermal stability, Tg_h, Tg, tensile strength/modulus, and storage modulus than NH₄OH/Cu(OH)₂-based ones at the same chain extender. On the other hand NH₄OH/Cu(OH)₂-based samples had higher conductivity and stronger antibacterial halo than TEA-based samples.     

聚合物片晶中链折叠模型的对称性讨论

本文从对称的观点讨论了在聚合物片晶中链折叠的问题.提出只有当分子链在折向相反方向后对称性不改变时,近邻规整折叠才是可能的.它是近邻折叠的必要条件.根据折叠时“对称性不变”这一论点,可以预言分子链近邻规整折叠的可能性及可能的折叠方向.     

Synthesis and Crystal Structures of Two Cadmium Coordination Chain Polymers

Hydrothermal reactions of cadmium precursors with 2, 2′‐bipyridine, fumaric acid or NaN₃ in basified aqueous solutions gave rise to two cadmium complexes [Cd(bipy)(fum)(H₂O)]_n ( 1 ), and [Cd(bipy)(μ_{1, 1}‐N₃)₂]_n ( 2 ) (fum = fumarate dianion), which were characterized by X‐ray crystallography. Complex [Cd(bipy)(fum)(H₂O)]_n ( 1 ) crystallizes in the orthorhombic system, space group Pbca, with a = 9.0488(8), b = 16.246(3), c = 19.810(4) Å, and Z = 8 while complex [Cd(bipy)(μ_{1, 1}‐N₃)₂]_n ( 2 ) in the monoclinic system, space group C2/c, with a = 12.378(3), b = 14.788(3), c = 6.6139(13) Å, β = 91.49(3)°, and Z = 4. The photoluminescence spectra for compounds 1 and 2 have also been studied.     

Octa-membered Water Ring Chain Based on Sulfonic Group in Ni(Ⅱ) Complex with 2-[(E)-(2-Oxidophenyl)methyleneamino]Ethanesulfonato and 2,2''-Bipyridinyl

The title compound, [Ni(tssb)(2,2-bipy)2]·5(H2O) 1 (tssbH2 =2-[(E)-(2-oxido-phenyl)methyleneamino]ethanesulfonato, 2,2-bipy = 2,2'-bipyridinyl), belongs to orthorhombic,space group Pbcn with a = 20.3983(18), b = 17.6929(15), c = 17.0897(15) nm, V = 6167.8(9) nm3,Mr= 688.38, Z = 8, Dc = 1.481 g·cm-3, F(000) = 2880, μ = 0.758 mm-1 and S =1.099. Each NiⅡ atom is six-coordinated by one N and one O atoms from one tssb2- anion and four N atoms from two 2,2-bipy ligands to give a distorted octahedral geometry. Noticeably, there exists a rare octa-membered water ring which presents a 1D chain by sulfonic group.     

Fluorine-bridged chain compounds as models in magnetochemistry: structures and magnetism of (imidH)2[Fe2oxF6] and [Fe2oxF4(DMSO)4]

The crystal structure of a new Fe(III) dimer obtained by fluorination of FeCl₃ with Me₃SnF in the presence of oxalic acid and crystallization from dimethyl sulfoxide (DMSO) has been determined: [Fe₂oxF₄(DMSO)₄] 1, Space group P2₁/n, Z=2, a=7.259(2), b=11.409(3), c=13.374(2) Å, β=97.26(1), R=4.47%. It shows a tetradentate bridging oxalato, equatorial cis fluorine and axial trans DMSO ligands.From an aqueous solution of FeF₃·3H₂O, oxalic acid, and imidazolium fluoride, crystals of (imidH)₂[Fe₂oxF₆] 2 could be precipitated. Space group Pban, Z=2, a=9.143(2), b=20.837(6), c=3.890(1) Å, R=2.51%. The structure shows anionic chains formed by bridging trans fluorine ligands connected, like in the dimer above, by oxalate anions to form a double chain. The magnetic properties were determined on powders by SQUID measurements. Mössbauer experiments were performed on the S=5/2 Fe³⁺ double chain of (imidH)₂[Fe₂oxF₆], where the anisotropy is of dipolar origin and is therefore very weak. The striking result is the characteristic aspect of two magnetic split spectra below T_N and additionally, the coexistence of a temperature dependent paramagnetic component (doublet) and the magnetic split spectra in the temperature range T_N=14.5 and T_H=40 K. The origin of that unusual behaviour is attributed to nonlinear excitations (magnetic solitons) in systems with small local anisotropy. Consequently, the domain wall width should be large. The subspectrum of the doublet was identified with intraband solitons. The relative intensity of the fast relaxing component increases with increasing temperature as ∝exp(−E_s/kT). From the slope of fractional intensity of the broadened doublet as a function of inverse temperature, the activation energy E_s/k=40(1) K was derived. Considering the results of magnetic susceptibility measurements of the intra-chain exchange constant J/k=−17.3(2) K, we found an anisotropy constant of D/k=0.15(2) K in agreement with our magnetic study. Additionally, parameters as the inter-chain constants J′/k=0.08(2) K and J″/k=0.60(5) K were calculated. Speculatively, from the experimental data of the magnetically split spectra the ratio (domain length/domain wall width) ≈ 2 was estimated at T_N, in agreement with the theoretical expectations. Finally, the results obtained for the double chain of (imidH)₂[Fe₂oxF₆] with weak anisotropy are compared with previously reported Mössbauer experiments on -doped powder of (ND₄)₂MnF₅, inelastic neutron scattering, and magnetic susceptibility measurements on single crystals of (ND₄)₂MnF₅ with strong anisotropy.     

RbFe[BP2O8(OH)]: Ein neues Borophosphat mit offen-verzweigten Vierer-Einfach-Tetraederketten

RbFe[BP₂O₈(OH)]: A New Borophosphate Containing Open-Branched Tetrahedral Vierer-Einfach Chains RbFe[BP₂O₈(OH)] is formed under mild hydrothermal conditions (T = 165–170 °C) from a mixture of RbOH_(aq), FeCl₂ · 4 H₂O, H₃BO₃ and H₃PO₄. The crystal structure of the monoclinic compound was solved by x-ray single crystal methods (space group P2₁/c, No. 14): a = 935.8(5) pm, b = 833.9(6) pm, c = 965.6(5) pm; β = 101.69(4)°; Z = 4. The anionic partial structure contains open-branched vierer-einfach chains [BP₂O₈(OH)]^4–, which are formed by alternating borate and phosphate tetrahedra sharing common corners. Fe³⁺ is in an octahedral coordination (FeO₅(OH)), while Rb⁺ is irregularly coordinated by ten oxygen-functions of neighbouring tetrahedra.     

Ferrimagnetic Behavior of meso-Tetrakis(2,3,5,6-tetrafluoro-4-methoxyphenyl)porphyrinatomanganese(iii) tetracyanoethenide, [MnTF4OMePP][tcne]⋅2 PhMe: Structural Evidence for a Second-Order Crystallographic Phase Transition

The quest to identify a new molecule-based magnet led to the discovery that the reduction of meso-tetrakis(pentafluorophenyl)porphyrinatomanganese(iii) chloride, Mn^IIITF₅PPCl, with sodium borohydride and its subsequent reaction with tetracyanoethylene (TCNE) forms the magnet [Mn^IIITF₄OMePP][tcne]. The structure undergoes a reversible phase transition (see picture) below −100 °C, which is not evident from either the magnetic or infrared data.     

高聚物溶液中大分子链尺寸的研究(Ⅲ)——一种测算高分子溶液第二维里系数的新方法

将高聚物溶液中大分子链尺寸对浓度的依赖关系与Zimm稀溶液第二维里系数的统计力学硬球模型相结合,借助聚合物的特性粘数、Mark-Houwink方程或分子量,计算聚合物-溶剂体系在稀溶液浓度范围内π/C或H·C/τ的模拟实验值.再以π/C或H·C/τ与浓度线型回归中的始斜率求体系的第二维里系数A₂,计算了30种聚合物-溶剂体系的295个不同分子量的A₂值,结果均与其实验值吻合较好,且明显优于其它理论模型测算的结果.     

用双硫酯链转移法合成嵌段聚合物

研究了以双硫酯为链转移剂进行的均聚和嵌段共聚物的合成 .首先合成大分子链转移剂 ,得到分子量可控、多分散性系数较小的均聚物PMMA、PBMA、PEMA、PEA、PBA、PMA、PSt,多分散性系数一般小于 1 30 .在相同的条件下 ,甲基丙烯酸酯类的聚合速度最快 ,苯乙烯其次 ,丙烯酸酯类最慢 .用末端带有双硫酯基团的PSt、PBMA、PBA为链转移剂 ,加入多种第二单体聚合得到实测分子量与理论分子量接近 ,且多分散性系数较小的两嵌段聚合物 .在链转移剂和引发剂的比例为 3∶1～ 6∶1的范围内 ,聚苯乙烯同样可以作为第一嵌段得到和其它酯类单体的两嵌段聚合物 .1 H NMR方法证明了聚合物的末端带有双硫酯基团 .嵌段聚合时必须加入微量的自由基引发剂以形成大分子自由基 ,达到较好的控制聚合效果