活性聚合法合成结构精确的含氟嵌段共聚物

结构精确的含氟嵌段共聚物具有优异而独特的化学和物理性能,有广阔的应用前景,因此受到广泛的关注.含氟嵌段共聚物可分为两类,一类是侧基含氟嵌段共聚物,另一类是主链含氟嵌段共聚物.活性聚合为嵌段共聚物的合成提供了最为重要的方法,利用它可以合成结构精确、分子量可控、分子量分布窄的嵌段共聚物.根据单体的反应特性选择不同的聚合方法,可以得到不同的含氟嵌段共聚物.本文主要综述了近几年利用各种活性聚合方法合成结构精确的含氟嵌段共聚物方面的进展.     

CRYSTALLIZATION KINETICS OF ETHYLENE-PROPYLENE COPOLYMERS PREPARED BY LIVING COORDINATION POLYMERIZATION

In this paper,crystallization kinetics of a series of ethylene-propylene copolymers prepared by living polymerization coordination catalyzed by a fluorinated bis(phenoxyimine)Ti catalyst(FI-EP copolymers)was studied,and was compared with that of ethylene-propylene copolymers prepared by a conventional Ziegler-Natta catalyst(ZN-EP copolymers).It is found that,the Avrami exponent and the crystallization rate constant of the FI-EP and ZN-EP copolymer show similar dependence on crystallization temperature,bu...     

裂解色谱法分析苯乙烯-丙烯酰胺共聚物

本文报道了用裂解色谱法分析一种新型的苯乙烯-丙烯酰胺共聚物的研究结果。考察了裂解温度、共聚物组成同主要裂解产物之间的相关性。提出了用相关曲线对不同类型共聚物的组成进行定量测定和鉴别的方法。讨论了由于分子链结构的差别导致无规和嵌段共聚物的不同的裂解行为。     

Synthesis and characterization of novel biodegradable copolyesters by transreaction of poly(ethylene terephthalate) with copoly(succinic anhydride/ethylene oxide)

Poly(ethylene terephthalate)/copoly(succinic anhydride/ethylene oxide) copolymers, (PET/PES copolymers) were synthesized by the transreaction between PET and PES and characterized with GPC, ¹H NMR, and DSC. Most of the copolymers obtained were random copolymers. The films cast of these copolymers were transparent. The thermal, mechanical properties, and biodegradability of the copolymers obtained were studied with respect to the composition and lengths of aliphatic and aromatic units in the copolymers. In the copolymers having high PET content, the melting points, due to the PET segment, were observed by DSC measurement, although the fusion heats of the copolymers were small. The enzymatic hydrolyzability by a lipase from Rhizopus arrhizus and biodegradability by activated sludge of the copolymers decreased with an increase in PET content. When the length of succinic acid unit in the copolymer was below 2, the hydrolyzability of the copolymers decreased considerably. The tensile strengths of the cast films prepared from the copolymers synthesized by the transreaction increased with an increase in PET content, whereas, the elongations at break decreased. Their tensile strengths were half, and the elongations were double compared to those of PET homopolymer film. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4478–4489, 2000     

非线形嵌段共聚物的合成

主要介绍了非线形嵌段共聚物,如星型嵌段共聚物、杂臂星型共聚物、梳型聚合物等的合成方法,包括多官能团引发剂法、大分子引发剂法等。各种活性聚合方法,如阳离子开环聚合、原子转移自由基聚合(ATRP)和氮氧稳定自由基聚合等都可以用于合成非线形嵌段共聚物。     

~(13)C-NMR方法研究酚酞聚芳醚酮砜共聚物的序列结构

通过亲核共缩聚合成了一系列酚酞聚芳醚酮砜共聚物和嵌段共聚物 ,并利用1 3C NMR方法研究了共聚物的链结构 ,通过观察酚酞单元中三个位置的季碳原子的化学位移及其相应强度的变化 ,计算共聚物中不同链段的共聚物的组成、平均序列长度和无规度 .结果表明 ,除嵌段共聚物外 ,其它共聚物的无规度均接近 1 ,表明共聚物为无规共聚物 ,而且对三个位置的季碳原子分析均得出了相同的结果 .     

Synthesis and characterization of conjugated diblock copolymers

This paper reports the synthesis and characterization of a new class of diblock copolymers (co-oligomers), rod-rod conjugated diblock copolymers. A general synthetic strategy is outlined, and the structures of the copolymers (oligothiophene-co-oligophenylenevinylene) are fully characterized. It was found that these copolymers exhibit efficient intramolecular energy transfer. An interesting self-assembly ability of these rod--rod copolymers was also revealed.     

醋酸乙烯酯及丙烯酸丁酯半连续法乳液共聚合

我们曾对丙烯酸丁酯(BA)与醋酸乙烯酯(VAc)一步法乳液共聚合机理进行过研究,并对其胶膜及胶乳性能进行了表征。结果表明一步法共聚乳胶粒具有类似于“核壳结构”的形态,其内核由BA含量高的共聚物组成,外壳基本是PVAc均聚物,对此用不同的方法进行了验证。在此基础上我们以VAc-BA进行了半连续法乳液共聚合,以与一步法相比较,从而探讨反应过程与胶粒结构及材料性能的关系。     

三烯丙基异氰尿酸酯交联共聚物的研究(Ⅱ)——醇解物的制备、结构及其性能

将醋酸乙烯酯与三烯丙基异氰尿酸酯共聚物进行皂化制得含有羟基和羧基盐的共聚物以增强共聚物的亲水性,用作气相色谱固定相,考察了不同交联度对皂化反应的影响,测定了皂化后共聚物的孔结构参数及溶胀性能,并对该固定相的色谱性能进行评价。     

环形嵌段共聚物的胶束化行为模拟简

利用Monte Carlo模拟,对比了相同组成下环形二嵌段共聚物AB和线形三嵌段共聚物ABA在选择性溶剂中的胶束化行为. 结果发现,相同链组成的环形和线形嵌段共聚物的临界胶束浓度(cmc)的差别与A嵌段的比例(fA)及B嵌段间的吸引强度(ε)密切相关. 在fA较小、ε较大的情况下,相应环形嵌段共聚物的cmc值更小;而在fA较大、ε较小的情况下,线形嵌段共聚物的cmc值更小. 为了进一步理解胶束化行为同fA及ε的关系,计算了胶束化过程中熵和势能部分对自由能的贡献. 结果表明,在所研究的fA和ε范围内,环形嵌段共聚物形成胶束时的熵损失更小,因而从熵贡献角度来看,环形嵌段共聚物更易发生胶束化. 而从势能贡献角度来看,当fA较小、ε较大时,环形嵌段共聚物形成胶束时势能有较大程度的降低,对自由能的贡献更大,因而此时环形嵌段共聚物更易发生胶束化. 而当fA较大、ε较小时,线形嵌段共聚物形成胶束时势能有较大程度的降低,对自由能的贡献更大,因而此时线形嵌段共聚物更易发生胶束化. 由此可见,对体系的胶束化自由能进行系统分析,有助于更好地理解环形和线形嵌段共聚物的胶束化行为.     

高交联大孔苯乙烯/二乙烯苯共聚物的合成及其孔结构的研究Ⅱ

本文对高交联大孔苯乙烯/二乙烯苯共聚物在干态、湿态与溶胀态的孔结构进行了研究。结果表明,在不同的状态中,高交联共聚物的孔结构是不相同的,它们的孔结构会发生变化。但是,它们的孔结构变化远小于低交联共聚物,也就是说,高交联大孔共聚物的孔结构比低交联共聚物的孔结构稳定。 鉴于高交联大孔共聚物的孔结构较稳定,作者把它用作高效液相色谱的进行了初步实验。结果表明,高交联共聚物可做为高效液相色谱的载体固定相。     

Temperature responsive methacrylamide polymers with antibacterial activity

<正>A new methacrylamide monomer,hexylamine methacrylamide(MAHA),was synthesized and used in polymerizations.The homopolymer of MAHA and its copolymers were synthesized by free radical polymerization techniques with N-isopropyl acrylamide(NIPAAm) in two different compositions.The quaternization of the homopolymer and copolymers were carried out using 1-bromopropane.The copolymers with NIPAAm and a low MAHA content showed temperature-responsive behavior in an aqueous environment.The lower critical solution temperatures(LCSTs) of these polymers varied between 32℃and 44℃.The LCSTs of quaternized copolymers were higher than those of neutral copolymers because they were more hydrophilic.The obtained homopolymers and copolymers were tested for antibacterial activities against S.aureus and E.coli.The quaternized water-soluble copolymers showed antibacterial activities against S.aureus.The quaternization resulted in the synthesis of both antibacterial and temperature-responsive copolymers.     

Solution properties of styrene-p-chlorostyrene diblock copolymers—I. Conformational behaviour in dilute solutions

The conformational behaviour of styrene-p-chlorostyrene diblock copolymers in dilute solutions was studied and compared with that of the corresponding triblock copolymers. Eight styrene-p-chlorostyrene diblock copolymers, of almost equimolar composition but with different molecular weights, were prepared using an anionic polymerization technique. The intrinsic viscosities of the copolymers were measured in non-selective solvents, such as toluene and 2-butanone, and in a selective solvent, cumene. The osmotic second virial coefficients of the diblock copolymers were measured in toluene. The data were analysed on the basis of two parameter theories. The unperturbed dimensions for the diblock copolymers can be expressed as a composition average of those for the parent homopolymers and the long-range interaction parameters of the diblock copolymers in toluene, 2-butanone and cumene are smaller than those of the triblock copolymers of the same composition. It means that the diblock copolymer chains in these 3 solvents had a more compact conformation than the triblock copolymers of the same composition and molecular weight.     

Modeling branched polyethylene: copolymers possessing precisely placed ethyl branches

A structural investigation of precise ethylene/1-butene (EB) copolymers has been completed using step polymerization chemistry. The synthetic methodology needed to generate four model copolymers is described; their primary and higher level structure is characterized. The copolymers possess an ethyl branch on every 9th, 15th, and 21st carbon along the backbone of linear polyethylene. Melting points and heats of fusion decrease with increased branch frequency. Differential scanning calorimetry and infrared spectroscopy show highly disordered crystal structures favoring ethyl branch inclusion. On the other hand, the EB copolymers contain high concentrations of kink and gauche defects independent of branch frequency. These model copolymers are compared with random copolymers produced using traditional chain chemistry and previously synthesized ADMET EP copolymers.     

疏水化修饰的聚N-异丙基丙烯酰胺高分子的水溶液性质研究

为了研究不同疏水化修饰的聚Ｎ 异丙基丙烯酰胺（ＰＮＩＰＡＭ）高分子的水溶液性质,合成了一系列Ｎ 异丙基丙烯酰胺（ＮＩＰＡＭ）和长链丙烯酸酯及丙烯酸胆固醇酯的共聚物．利用表面张力法证实了该类共聚物在室温下都具有良好的表面活性,在水溶液中能够形成胶束．利用荧光探针法,研究了共聚物的低温临界溶液温度（ＬｏｗｅｒＣｒｉｔｉｃａｌＳｏｌｕｔｉｏｎＴｅｍｐｅｒａｔｕｒｅ,ＬＣＳＴ）,发现,随着丙烯酸酯碳链及其配比（摩尔投料比）的变化,共聚物的ＬＣＳＴ变化不明显,但它们都比均聚的ＰＮＩＰＡＭ要低;利用荧光偏振法研究了共聚物在水溶液中的微粘度,发现其微粘度不随共聚物中丙烯酸酯链长和配比的变化而变化,说明了该类共聚物在室温下能够形成相类同的胶束内核．     

Antimicrobial and hemolytic activities of copolymers with cationic and hydrophobic groups: a comparison of block and random copolymers

Random and diblock copolymers of 2-(N,N-dimethylamino)ethyl methacrylate and butyl methacrylate are prepared by ATRP. As mimics of cationic antimicrobial peptides, the random and diblock copolymers show similar antimicrobial activities. In contrast, the diblock copolymers have much lower hemolytic activities than the random copolymers. The cell selectivity (HC(50)/MIC, where HC(50) is the concentration to lyse 50% of human red blood cells and MIC is the minimum concentration to inhibit bacterial growth) of the diblock copolymers are 150 to 27,500 times higher than that of random copolymers with similar compositions.     

刚性链嵌段共聚物的研究（Ⅳ）──聚醚醚酮／苯酞圈型聚芳醚砜有规嵌段共聚物的合成与部分性能

以聚醚醚酮（ＰＥＥＫ）和苯酞圈型聚芳醚砜（ＰＤＣ）齐聚物为原料，通过溶液缩聚法制备了ＰＥＥＫ／ＰＤＣ有规嵌段共聚物系列样品。经ＤＳＣ、ＷＡＸＤ、ＴＧＡ、ＤＭＡ等方法研究表明：共聚物没有微相分离现象；其结晶属于简单正交晶系，ＰＤＣ含量对共聚物结晶行为产生很大影响；热稳定性随ＰＤＣ含量增加而明显降低；共聚物具有优异的力学性能，拉伸强度和储能模量高于ＰＥＥＫ。     

PLA大分子单体接枝NVP共聚物的合成与性能

制备了末端为双键的功能化聚乳酸大分子单体(PLA-HEMA),并以此大分子单体与N-乙烯基吡咯烷酮(NVP)进行自由基溶液共聚,合成了具有亲水性PVP-PHEMA主链和疏水性PLA支链的接枝共聚物。用FT-IR1、H-NMR、GPC、DSC、表面接触角测定研究了共聚物的结构与性能。结果表明:共聚物为非晶聚合物;NVP的摩尔投料量对共聚物的性能有显著影响,随NVP投料量增大,共聚物的分子量有所下降,玻璃化转变温度(Tg)增大;由于亲水性PVP和PHEMA链段的引入,共聚物的亲水性优于相应的线型聚乳酸材料。     

聚砜-尼龙6嵌段共聚体的溶液性质及其与聚砜、尼龙6均聚物的相容性的研究

<正> 我们曾在前二篇文章中指出非晶型双酚A聚砜(以下用B表示)与结晶形尼龙6(以下用N表示)经共混得到的共混物很脆,而聚砜-尼龙6嵌段共聚物(以下用B-N和N-B-N表示)却具有较B或N更优的耐溶剂性和耐水性,但是嵌段共聚物中B组分含量不能超过25％,这样就限制了材料的使用范围,然而由于B-N(或N-B-N)在同一分     

Adsorption of polymers at the solution–solid interface. XIV. Adsorption and steric stabilization with styrene–acrylonitrile copolymers

The adsorption of random copolymers of styrene and acrylonitrile of azeotropic composition from their trichloroethylene solutions onto precipitated silica exhibits a maximum at intermediate molecular weights. These copolymers are able to stabilize dispersions of some, but not all, grades of precipitated silica; here, too, a maximum effect is found at intermediate molecular weights. Copolymers are partially desorbed by ethyl cyanide, which destabilizes silica dispersions. Block copolymers of low acrylonitrile contents do not stabilize well but, when preadsorbed, affect the behavior of subsequently adsorbed random copolymers. In particular, high molecular weight random copolymers flocculate the pretreated silica; silica with grafted polyacrylonitrile chains may also be flocculated by these copolymers.