Evolution of Fiber Morphologies during Poly (acrylonitrile) Electrospinning

Summary: In this study, we used a facile approach to examine the evolution of fiber morphologies during electrospinning, via solidifying the newly electrospun polyacrylonitrile (PAN) nanofibers in an ethanol bath at different electrospinning distances (2 cm to 10 cm). It has been observed that a massive jet-thinning took place at the initial stage of whipping instability, followed by uneven fiber-stretching. The fiber-stretching at the later whipping stage was mainly concentrated on beaded fiber sections, which improved the uniformity of the resultant fibers.     

Synthesis of Poly(dialkylphosphazenes) from N-Silylphosphinimines

Many N-silylphosphinimines Me₃SiN?P(X) RR′ undergo facile thermal decomposition with elimination of substituted silanes Me₃SiX and formation of cyclic or polymeric phosphazenes (RR′PN). The process which is a new, general synthesis of phosphazenes has been used to prepare poly(dimethylphosphazene), (Me₂PN), in nearly quantitative yield from Me₃SiN?P(OCH₂CF₃)Me₂. Convenient synthetic routes to the necessary silicon-nitrogen-phosphorus precursors are described and the results of their decomposition reactions are reported.     

从含氢硅油制取水性氟硅聚合物

在无溶剂的条件下, 通过硅氢加成法将烯丙基聚氧乙烯聚氧丙烯醚, 氟化丙烯酸烷基酯接枝共聚到甲基含氢硅油侧链, 成功地合成了一系列有机氟硅聚合物. 通过高速剪切乳化法可制得不同质量投料比时的水性氟硅聚合物水分散物. 采用FTIR, ¹H NMR和TEM对有关产物和乳液进行了结构分析, 并进一步系统研究了水分散物表面张力, 流变性等性能, 结果表明: 质量分数为2.0%的水性氟硅聚合物水分散物的表面张力降低至22.00～26.00 N/m, 其黏度随着剪切速率的增大有剪切变稠现象发生, 且不同质量投料比时, 其粒子粒径大小及形状也有较大差别.     

聚丁二酸乙二醇酯的合成

以十氢萘为溶剂,丁二酸和乙二醇直接聚合,合成了高相对分子质量的聚丁二酸乙二醇酯(PES),其结构经1H NMR和IR表征。考察了单体比例对聚合反应的影响,结果表明,当n(乙二醇)∶n(丁二酸)=1.01∶1.00时,合成的PES数均相对分子质量最高(48 640),产率93%。同时测定了PES的力学性能和热性能。     

苯并双噁唑类聚合物的合成

详细介绍了以4,6-二氨基间苯二酚盐酸盐(DADHB)为原料,采用多聚磷酸法、三甲基硅烷基化法、中间相聚合法、单体成盐法合成聚对苯撑苯并双噁唑(PBO),还有以4,6-二硝基间苯二酚(DNR)为原料,先选择还原制得4-氨基-6-硝基间苯二酚盐酸盐,进而与对甲氧羰基苯甲酰氯进行缩环合获得苯并噁唑化合物,再催化加氢合成AB型PBO新单体2-(对甲氧羰基苯基)-5-氨基-6-羟基苯并噁唑,最后自缩聚反应制备PBO的新路线.另外,本文还介绍了直链烯烃型、直链脂肪烷烃型、稠环芳烃型、联苯取代基型、杂环型、聚醚型等苯并双噁唑类聚合物的合成方法.     

Prospect of Sulfurized Pyrolyzed Poly(acrylonitrile) (S@pPAN) Cathode Materials for Rechargeable Lithium Batteries

Lithium–sulfur (Li–S) batteries are one of the most promising next‐generation batteries owing to their ultra‐high theoretical energy density and that sulfur is an abundant resource. During the past 20 years, various sulfur materials have been reported. As a molecular‐scale sulfur‐composite cathode, sulfurized pyrolyzed poly(acrylonitrile) (S@pPAN) exhibits several competitive advantages in terms of its electrochemical behavior. Although it was first reported in 2002 S@pPAN is currently attracting increasing attention. In this Minireview, we summarize its molecular model and explore the correlation between its structure and its exceptional electrochemical performance. We classify the modification strategies into three types, including material improvement, binder, and electrolyte screening. Several research and development directions are also suggested.     

聚酯酰胺的合成

聚（酯酰胺）（PEA）的主链中同时具有酯键和酰胺键,兼具了聚酯（polyester）的生物降解性和相容性以及聚酰胺（polyamide）优异的机械性能,在药物控释、组织工程以及热塑性弹性体等领域应用广泛。缩合聚合是合成聚酯酰胺最初的方法,近年来开环聚合（ROP）成为制备聚酯酰胺的主要策略,本文从环状单体均聚、环状单体共聚、环状单体和线形单体共聚等方面总结了聚酯酰胺合成的研究进展。同时,介绍了基于多组分聚合反应（MCP）的新合成方法,并对聚酯酰胺材料的发展进行了探讨和展望。     

Poly(vinyl acetate) as a template for the radical polymerization of acrylonitrile

The template polymerization of acrylonitrile (AN) along with atactic-poly(vinyl acetate) of M _v (47,090), at 60°C for 120 min in dimethyl formamide (DMF) has been studied dilatometrically to study the effects of template, monomer, and initiator (benzoyl peroxide) concentration upon kinetics. Viscometric measurements showed that complexation between at-PVAc and PAN was maximum when template/polymer ratio was 1:1 and time required for complete complexation was 15 min. The overall energy of activation was 57.76 and 77.01 kJ/mol in the presence and absence of, PVAc, respectively. The overall system follows mechanism I, i.e., the monomer molecules get adsorbed on the surface of the template macromolecules and then propagation proceeds.     

The Synthesis of Poly(Dimethylsiloxane-b-Isobutylene-b-Dimethylsiloxane) and Poly-(Dimethylsiloxane-b-Isobutylene-b-Dimethylsiloxane) from Alcohol-Telechelic Polyisobutylenes

The purpose of these studies was to combine polydimethylsiloxane (PDMS) and polyisobutylene (PIB) sequences into novel triblock, PDMS-b-PIB-b-PDMS, and multiblock, (-PDMS-b-PIB-b-PDMS-)n, copolymers. The key toward syntheses was the definition of conditions for the initiation of living anionic polymerization of hexamethyl-cyclotrisiloxane (D₃) at the CH₂OLi termini of well-defined tele-chelic PIB sequences. Subsequent deactivation of living D₃ polymerization charges with Me₃ SiCl yielded the target triblock whereas stoichiometric amounts of Me₂ SiCl₂ gave the multiblock copolymer.     

Synthesis of Poly(galactaramides) from Alkylene- and Substituted Alkylenediammonium Galactarates

Polyhydroxypolyamides (PHPAs) represent a class of synthetic polyamides derived from aldaric acid and diamine monomer units. This paper describes the synthesis of some poly(galactaramides), a class of polyhydroxypolyamides, that employs alkylene and substituted alkylenediammonium galactarate salts, with 1:1 molar equivalency of the diacid and diamine monomer components, as precursors for the polyamides. The salts were treated with acid/alcohol and then base in order to initiate the polymerization in methanol. The polyamides, labeled as prepolyamides, precipitated from solution and were then subjected to a second polymerization (postpolymerization) in a different solvent to produce a generally larger polyamide, labeled as a postpolyamide.     

Poly(acrylonitrile) ultrafiltration membranes. II. Membrane morphology and permeation characteristics

The rheology and phase‐boundary characteristics of various solutions comprising three polyacrylonitrile (PAN) grades dissolved in solutions of N,N‐dimethylformamide + salt (LiCl, ZnCl₂, or AlCl₃) additives were correlated with the resulting membrane morphology as determined by microscopy and permeability measurements. The phase separation characteristics of the dope solution were not markedly affected by the PAN molecular weight (MW); however, they were affected by the salt additive. For higher MW grades, the effect of salt addition can also be masked by the increased self‐association tendency of the polymer chains. PAN‐B and ‐C membranes were clearly less asymmetric in structure than the lower MW PAN‐A–based membranes. This is attributed to the higher viscosity/lower diffusivity of the PAN‐B and ‐C solutions, which results in slower solvent–nonsolvent exchange during the phase inversion process. Two factors reduce the incidence of surface defects (increased bubble points): (a) higher solution viscosity dampens surface perturbations during phase inversion, and (b) phase inversion pathways resulting in more homogenous morphology lead to membranes with higher bubble points. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2074–2085, 2005     

可溶性聚对二乙炔苯的合成与表征

一些π-共轭高聚物由于具有优良的荧光性能或三阶非线性光学性能而引起了人们极大的兴趣,合成新型可溶性π-共轭高聚物的研究已成为近年来的研究热点.对二乙炔苯的聚合研究已有报道.     

聚甲基丙烯酸甲酯型高分子染料的合成

高分子染料的合成研究起于６０年代初［１］．１９７３年，Ｍａｒｅｃｈａｌ等实现了无色高分子材料与有色染料分子的化学键合［２～３］．目前，高分子染料已广泛应用于化妆品、涂料、填料、食品等领域并开始探索在液晶显示、半导体材料、激光记录、非线性光学材料、亲和...     

聚环氧氯丙烷的合成与表征

环氧丙烷-三氯化铁、环氧氯丙烷-二乙基氯化铝和铝卟啉-环氧氯丙烷体系是合成分子量为10~4数量级晶态和10~5数量级非晶态聚环氧氯丙烷的比较理想的体系。利用合成产物的分级试样确定了非晶态聚环氧氯丙烷的Mark-Houwink方程。     

聚硅乙炔烷的合成与性能研究

70年代初苏联学者首次报道了聚硅乙炔烷的合成^[1],1973年有人用炔化钙和二甲基二氯硅烷在熔融盐中反应,结果得到四环体物(Me₂SiC≡C)₄^[2]。为了研究这类聚合物的性能,我们采用了新的合成路线合成可熔的聚硅乙炔烷。乙炔和格氏试剂发生交换反应,生成炔基双格氏试剂,它和有机二氯硅烷发生缩聚反应,生成聚硅乙炔烷。     

聚2,5-呋喃二甲酸1,8-辛二酯的聚合反应

以可再生资源2,5-呋喃二甲酸(FDCA)和1,8-辛二醇(1,8-ODO)为原料,钛酸四丁酯为催化剂,采用直接酯化法制得聚2,5-呋喃二甲酸1,8-辛二酯(1,8-POF)。 考察了原料配比、催化剂用量、酯化温度、缩聚温度及缩聚时间对聚合反应的影响,结果表明,当n(FDCA)∶n(1,8-ODO)=1∶1.2,钛酸四丁酯摩尔分数为0.3%,酯化温度为240 ℃,缩聚温度为260 ℃,缩聚时间为300 min时,缩聚产物的比浓粘度最高（2.1 dL/g）,端羧基含量最低（5.8 mol/t）。 与乙二醇相比,采用1,8-辛二醇为单体降低了酸醇的摩尔比,减少了醇的消耗,同时得到了较高分子量的聚合物。 气质联用仪对酯化馏出液和缩聚产物真空抽出物进行了分析,结果表明,酯化馏出液的主要成分是水,并含有少量的1,8-ODO;缩聚产物真空抽出物的组成为环己酮（56%）、顺式-3-辛烯醇（18%）、4-甲基-3-戊烯-2-酮（17%）和4-羟基-4-甲基-2-戊酮（9%）。     

甲基丙烯酸丁酯接枝纤维素的制备

为开发纤维素基吸油材料,以棉浆粕为基材、甲基丙烯酸丁酯(BMA)为单体、乙二醇二甲基丙烯酸酯为交联剂,采用悬浮接枝聚合法合成了BMA接枝纤维素的聚合物。采用红外光谱(FT-IR)、X射线衍射(XRD)、扫描电镜(SEM)、热重(TG)、差热(DSC)等手段对所得吸油材料结构进行了表征。考察了引发剂的种类及用量、接枝单体及交联剂用量、反应温度、反应时间等因素对BMA接枝纤维素聚合物的接枝聚合反应性能及吸油性能的影响。结果表明:当m(棉浆粕)∶m(K2S2O8)∶m(BMA)∶m(乙二醇二甲基丙烯酸酯)=1∶0.025∶1.5∶0.005,75℃下恒温反应6 h,合成的BMA接枝纤维素的接枝率最高(36.2%),均聚物含量相对较低(5.8%),且吸油性能优良。     

聚对苯基苯酚取代磷腈的合成与表征

环状三聚六氯化磷腈在α-氯代萘中开环聚合得到聚氯化磷腈.后者与对苯基苯酚钠反应合成了标题聚合物.测定了该聚合物的IR、~1H NMR谱.GPC估计其数均分子量为6×10~4.扭辫分析表明,该聚合物的玻璃化转变温度与粘流温度分别为0℃和130℃,硫化温度为210℃.