聚硫醚醚酮(砜)芳香环状低聚物的合成与自由基开环聚合

在“拟高稀释”条件下,通过亲核缩聚反应高产率地合成了含硫醚键的芳香醚环状低聚物.应用核磁、GPC和激光质谱(MALDI-TOFMS)等手段对环状低聚物的结构进行了确认,并研究了环状低聚物的组分分布.聚硫醚醚酮环状低聚物在硫醚自由基的引发下进行快速熔融聚合,得到热稳定性很好的高分子量线性聚合物.     

聚间苯硫醚和聚对苯硫醚的对比表征

聚对苯硫醚[poly(pphenylenesulfide),简称pPPS]的分子链是由对苯撑基和硫原子交替连接构成而使制品抗冲击能力差[1](有些研究者用共聚或共混的方法在pPPS中引入间位结构来达到减少其结晶度,增强韧性的目的)。余自力等[2]用硫磺溶液法合成了mPPS、pPPS及其共聚物,认为在pP...     

苯硫醚环状低聚物的合成与初步聚合研究

以硫化钠和对二氯苯为原料,加入锂盐复合助剂,在六甲基磷酰三胺溶剂中,常压下合成了苯硫醚环状低聚物（CPS）,研究了助剂用量、单体浓度和反应时间等条件的影响,并对合成的产物进行了初步表征和热聚合试验。结果表明：采用助剂后,可以在提高反应物浓度、缩短反应时间的同时,得到较高的合成产率;合成产物的红外、紫外光谱与文献一致;CPS的热聚合产率高。     

环状碳酸酯低聚物的合成及其开环聚合的研究

环状碳酸酯低聚物的合成及其开环聚合的研究陈雨萍魏玮李革（中国科学院化学研究所工程塑料国家重点实验室北京１０００８０）关键词环状碳酸酯低聚物，聚碳酸酯，开环聚合环状单体的开环聚合在合成高聚物方面具有突出的优点，即在聚合过程中没有副产物、热效应低、聚合...     

环状芳香低聚物的合成及应用研究进展

综述了近年来环状芳香低聚物的合成及应用研究发展状况,对其合成方法和应用情况进行了综述和分析,并对今后的研究发展进行了预测。     

基质辅助激光解吸电离质谱表征新型环状聚芳酯预聚体

应用基质辅助激光解吸电离质谱技术对新型环状聚芳酯预聚体进行了表征，从而确定了该环素聚合物不同聚合度（ｎ＝１，２……８）的存在，获得了满意的结果。实验证明本方法是测定环状聚合物不同聚合度快速、有效、准确的方法。     

用MALDI-TOF-MS法表征系列环状预聚体

应用基质辅助激光解吸电离飞行时间质谱（MALDI－TOF－MS）技术对系列环状预聚体进行了表征,分别确定了系列环状预聚体各自不同的聚合度,同时对它们的结构进行了确认,获得了满意的结果。实验结果表明MALDI－TOF－MS是分析环状预聚体准确、快速工具之一。     

MALDI-TOF质谱表征聚芳醚酮环状低聚物及其组分分布

应用介质辅助激光解吸离子化飞行时间质谱(MALDI-TOFMS),以二羟基苯甲酸为介质、N₂(337nm)为激光源,对两种聚芳醚酮环状低聚物的结构进行了确认,研究了环状低聚物不同聚合度组分的分布规律,并且与GPC质量分析法作了比较,实验结果表明,MALDI-TQF质谱是分析环状低聚物的准确、快速的工具之一.     

MALDI-TOFMS表征均聚芳香硫酚环状低聚物

采用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)对4种合成的均聚芳香硫酚环状低聚物进行了质谱表征;并且对4种合成产物的组成、结构进行了分析及确认;得到了均聚芳香硫酚环状低聚物的相对分子质量及其分布信息;研究结果显示：MALDI-TOF MS是分析均聚芳香硫酚环状低聚物的有效工具。     

亲电缩聚反应合成芳香环状低聚醚酮砜及其开环聚合

"假高稀"条件下,以邻苯二酰氯为酰基化试剂,Lewis碱NMP存在下,通过亲电缩聚反应高产率地合成了2种芳香环状聚醚酮砜低聚物,利用MALDI-TOF-MS,NMR,GPC,FTIR,DSC等手段对环状结构进行了精确的表征.在负离子引发剂联苯双酚钾存在下,环状低聚物3a进行熔融开环聚合,得到了高分子量的线型聚合物,Tg为221.8℃.利用流变仪监测了环状低聚物3a开环聚合过程中的流变行为,结果表明,开环聚合初期的引发阶段,熔融体的黏度低于10Pa.s,随着时间的延长,黏度快速增长,而且低黏度的引发阶段随着引发剂浓度的增加而变短.     

Crystal and molecular structures of cyclohepta(p-phenylene sulfide) and cycloocta(p-phenylene sulfide)

The crystal structures of two cyclic poly(phenylene sulfides) have been determined. The structure of the (p–C₆H₄–S)₁ heptamer contains four crystallographically independent molecules, which are related in pairs by approximate symmetry centers. The molecules in the pairs have similar conformations and form alternating monomolecular layers parallel to the ab plane. The molecule of the (p–C₆H₄–S)₈ octamer has S₄ crystallographic symmetry (a saddle-shaped conformation), and solvent molecules are found in the intramolecular cavities in the crystal.A. N. Nesmeyanov Institute of Organometallic Compounds, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 2, pp. 125–132, March–April, 1991.     

Cyclopenta(p-phenylene sulfide) and cyclotetra(p-phenylene sulfide): examples of a new macrocyclic series

Cyclotetrameric and pentameric(p-phenylene sulfides) have been isolated from poly(p-phenylene sulfide) and identified and charachterized.     

Synthesis and characterization of ran-copoly (p-phenylene sulfide sulfone/ketone)s

Random copoly(p-phenylene sulfide sulfone/ketone)s (PPSS/K) are prepared in high yield by the polycondensation of sodium hydrosulfide (NaSH) with bis(4-chlorophenyl) sulfone (BCPS) and 4,4′-dichlorobenzophenone (DCBP). The polymerization is conducted between 200–220°C, depending on the composition of the copolymer, and in the presence of water without any detrimental effects to the molecular weight. The copolymers with sulfone/ketone mole ratios (S : K) > 25 : 75 are amorphous, while the copolymers with S : K ratios ≤ 25 : 75 are crystalline. These materials form tough, creaseable films and exhibit a linear increase in the glass transition temperature with increasing sulfone content. Sulfuric acid solutions of the copolymers are dark orange to red and display an increasing λ_max in the uv-visible spectra as the S:K ratio of the copolymers decreases. © 1994 John Wiley & Sons, Inc.     

Electrical properties of ion-implanted poly(p-phenylene sulfide)

Ion implantation of impurities into thin films of poly(p-phenylene sulfide) (PPS) is found to increase the conductivity of the material by up to 12 orders of magnitude. The increase is stable under exposure to ambient conditions, in contrast to the instability of the conductivity increases in PPS produced by chemical doping with AsF₅. PPS films 0.1–0.2 μm thick are spin cast from solution onto interdigitated electrodes patterned on an oxidized silicon substrate. The room-temperature interelectrode resistance is measured as a function of implantation fluence. An estimate of film conductivity is obtained from this resistance with a simple model for the electrode and film geometry. A first experiment yielded similar conductivity increases for implantation of either arsenic or krypton. At a fluence of 1 × 10¹⁶cm^?;2, which corresponds to an average impurity concentration of 2.5 × 10²¹cm^?3, the conductivity reaches an apparently saturated value of 1.5 × 10^?5 (Ω cm)^?1. Infrared spectra of the films before and after implantation suggest that crosslinking may be present in the implanted films, and Auger studies show stoichiometric changes throughout the implanted layer. These results suggest that the observed conductivity changes are the result of molecular rearrangements produced by the implantation rather than the result of specific chemical doping. Specific chemical doping may, however, explain the results of a second experiment in which implantation of bromine resulted in substantially larger conductivities found to increase at an approximate linear rate from a value of 1.0 × 10^?4 (Ω cm)^?1 at a fluence of 1 × 10¹⁶ cm^?2 to a value of 4.0 × 10^?4 (Ω cm)^?1 at a fluence of 3.16 × 10¹⁶ cm^?2.     

Crystal and molecular structure of cyclohexa-(p-phenylene sulfide)

Institute of Heteroorganic Compounds, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 31, No. 3, pp. 160–162, May–June, 1990.     

Poole-Frenkel effect in amorphous poly(p-phenylene sulfide)

The conductivity of poly(p-phenylene sulfide) (PPS) amorphous samples sandwiched between metallic electrodes has been studied as a function of applied voltage, temperature, and electrode material. The voltage (U) dependence of the currents for electric fields within the range 10³–10⁶ V/cm exhibits exp βU^1/2 behavior with β = β_Schottky below the glass transition temperature (T_g ≊ 90°C), and β = β_{Poole-Frenkel} above T_g. Coordinated temperature measurements of dc currents with different metallic contacts and thermally stimulated currents (TSC) indicate, however, that the conductivity at T < T_g is consistent with the so-called “anomalous” Poole-Frenkel effect rather than the Schottky effect. Consequently, the p-type conductivity in amorphous PPS is proposed to be a bulk-limited process due to ionization of two different types of acceptor centers in the presence of neutral hole traps. © 1996 John Wiley & Sons, Inc.     

Isolation and characterization of stable iron(i) sulfide complexes

The first examples of iron(I) sulfide complexes are presented, in contrast with the +2 and +3 oxidation states that are well-known in synthetic and biological systems. Spectroscopic and computational studies show a high-spin d(7) configuration at the metal. Alkali metal cations play a key role in supporting the unusually low oxidation state.     

Ultraviolet photoelectron spectroscopy of poly(p-phenylene sulfide) (PPS)

Ultraviolet photoelectron spectra were measured for films of poly(p-phenylene sulfide) (PPS) prepared by vacuum evaporation. The threshold ionization potential was determined to be 6.0 ± 0.1 eV. The peaks in the photoelectron spectra are assigned by comparison with theoretical calculations, and the π bandwidths of PPS and related compounds are discussed.     

Drawing of poly(p-phenylene sulfide) by solid-state coextrusion

The effects of drawing temperature on the physical and mechanical properties of poly(p-phenylene sulfide) have been studied. A melt-quenched film was drawn by solid-state coextrusion both below (75°C) and above (95 and 110°C) the glass transition temperature T_g (85°C) of PPS. The maximum extrusion draw ratio (EDR_max) increased from 3.4 to 5.6 with increasing extrusion temperature T_e from 75 to 110°C. It was found that extrusion drawing just above the T_g of PPS (95°C) produced more stress-induced crystals. A high efficiency of draw in the amorphous region was achieved by extrusion at T_e-75°C. The tensile modulus at EDR_max decreased from 5.1 to 3.5 GPa with increasing T_e from 75 to 110°C. The low efficiency of draw for the samples extruded at 110°C is explained in terms of disentanglement and chain slippage during drawing due to a less effective network.     

Thermolysis of reactive oligo(p-phenylene sulfide) containing disulfide bond

Oligo(phenylene sulfide) (OPS) containing one disulfide bond at the end of the chain, which was obtained by the oxidative polymerization of diphenyl disulfide, had a relatively low Td_10%(temperature for 10% weight loss) of 412 °C because of degradation of the disulfide bond. But this thermal cleavage of the disulfide bond promoted the curing reaction through thiophenoxy radical formation. OPS was allowed to react with diiodobenzene at 220 °C. The thermal stability of OPS was improved through the consumption of the disulfide bond and the coupling of the chain.