Regioregulated Syntheses of Poly(aminopyridine)s by Pd‐catalyzed Amination Reaction

Regioregulated poly(aminopyridine)s were synthesized by a Pd‐catalyzed C N coupling reaction. The polymerization using Pd(0) and a bulky monodentate phosphine ligand distinctively produced the para‐linked and meta‐linked poly(aminopyridine)s, without the need for a protection process. The regioregularity of the polymer was confirmed by ¹H NMR spectroscopy. Model reactions were studied to evaluate the possibility of crosslinkage in the polymer. A large difference in reactivity was observed between 5‐amino‐2‐bromopyridine and 2‐amino‐5‐bromopyridine, which should have afforded same product. Density functional theory (DFT) calculations indicated that electron densities of the Br‐bound carbon atom and the pyridine‐nitrogen atom determine the reactivity of the monomers.

     

Poly(cyclodiborazane)s

This paper summarizes our recent works on the synthesis and properties of the organoboron polymers, especially poly(cyclodiborazane)s. The polymers consist of boron–nitrogen four-membered rings, and are highly stable against air and moisture. The obtained polymers exhibited interesting properties as a novel type of π-conjugated polymers with intramolecular charge transfer structure. Their stability and potential as functional materials would be important and informative both in industry and boron chemistry.     

Poly(thioester)s

Syntheses and properties of aliphatic and aromatic polythioesters (PTEs) were reviewed including polythiocarbonates and polythiourethanes. The content is subdivided into the following sections: PTEs of aliphatic α‐mercapto carboxylic acid, PTEs of ω‐mercapto carboxylic acids, PTEs derived from α,ω‐dimercapto alkanes, aromatic poly(thioester)s, aliphatic poly(thiocarbonate)s, aliphatic poly(thiourethane)s and aromatic polythiocarbonates. The synthetic strategies reviewed in this article include anionic and cationic ring‐opening polymerizations, polycondensations in bulk, polycondensations in solutions, interfacial polycondensations and in vitro enzymatic polycondensations.     

Poly(aryl ether amide)s

A general method for the preparation of poly(aryl ether amide)s has been developed where the generation of an aryl ether linkage is the polymer-forming reaction. The amide linkage was found to be sufficiently electron-withdrawing to activate halo-substituents towards nucleophilic aromatic substitution analogous to conventional activating groups (i.e., sulfone, ketone, etc.). Model reactions demonstrated that the amide-activated displacement occurred with high selectivity in near quantitative yield and was judged suitable as a polymer-forming reaction. Appropriately fluoro-substituted amides were prepared and subjected to displacement polymerization with bisphenoxides in a N-methyl-2-pyrrolidone (NMP)/N-cyclohexyl-2-pyrrolidone (CHP) solvent mixture. High molecular weight polymers with glass transition temperatures in the 200–225°C range were obtained. © 1993 John Wiley & Sons, Inc.     

Well-defined Poly(lactic acid)s Containing Poly(ethylene glycol) Side-chains

Poly(ethylene glycol) (PEG) side-chain functionalized lactide analogues have been synthesized in four steps from commercially available L-lactide. The key step in the synthesis is the 1,3-dipolar cycloaddition between PEG-azides and a highly strained spirolactide-heptene monomer, which proceeds in high conversions. The PEG-grafted lactides analogues were polymerized via ring-opening polymerization using triazacyclodecene as organocatalyst to give well-defined tri- and hepta-(ethylene glycol)-poly(lactide)s (PLA) with molecular weights above 10 kDa and polydispersity indices between 1.6 and 2.1. PEG-poly(lactide) (PLA) with PEG chain M(n) 2000 was also prepared but GPC analysis showed a bimodal profile indicating the presence of starting macromonomer. Cell adhesion assays were performed using MC3T3 E-1 osteoblast-like cells demonstrating that PEG-containing PLA reduces cell adhesion significantly when compared to unfunctionalized PLA.     

Multifunctional Poly(ethylene glycol)s

In the rapidly evolving multidisciplinary field of polymer therapeutics, tailored polymer structures represent the key constituent to explore and harvest the potential of bioactive macromolecular hybrid structures. In light of the recent developments for anticancer drug conjugates, multifunctional polymers are becoming ever more relevant as drug carriers. However, the potentially best suited polymer, poly(ethylene glycol) (PEG), is unfavorable owing to its limited functionality. Therefore, multifunctional linear copolymers (mf‐PEGs) based on ethylene oxide (EO) and appropriate epoxide comonomers are attracting increased attention. Precisely engineered via living anionic polymerization and defined with state‐of‐the‐art characterization techniques—for example real‐time ¹H NMR spectroscopy monitoring of the EO polymerization kinetics—this emerging class of polymers embodies a powerful platform for bio‐ and drug conjugation.     

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.     

Micellization and Thermogelation of Poly(ether urethane)s Comprising Poly(ethylene glycol) and Poly(propylene glycol)

A series of multiblock poly(ether urethane)s comprising poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) segments were synthesized. Their aqueous solutions exhibited thermogelling behavior at critical gelation concentrations (CGC) ranging from 8 to 12 wt%. The composition and structural information of the copolymers were studied by GPC and ¹H NMR. The critical micellization concentration (CMC) and thermodynamic parameters for micelle formation were determined at different temperatures. The temperature response of the copolymer solutions were studied and found to be associated with the composition of the copolymers.     

Improving Gene Delivery Efficiency of Bioreducible Poly(amidoamine)s via Grafting with Dendritic Poly(amidoamine)s

Dendritic poly(amidoamine)s (PAMAM)s were introduced into the side chains of disulfide‐containing poly(amidoamine)s via repetitive Michael addition and amidation. The bioreducible poly(amidoamine)s grafted with dendritic polyamidoamines showed high buffer capacity, low cytotoxicity and strong DNA binding ability at low N/P ratio. They were able to condense DNA into small sized polycation/DNA complexes, which degraded and released the incorporated DNA under reductive conditions. In comparison to the original disulfide‐containing poly(amidoamine) with aminoethyl side chain, the grafting of the bioreducible poly(amidoamine) with dendrimer greatly improved the transfection efficiencies of 293T and HeLa cells with foreign DNA at various N/P ratios. The structure–gene delivery property relations of dendrimer‐grafted polycations will provide valuable insight into the design of highly efficient and less toxic polycationic gene carriers.

     

聚噻吩的合成方法

自从1977年白川英树等发现聚乙炔这种导电聚合物以来,打破了高分子材料长期以来被认为是绝缘体的观点。随后聚苯胺、聚吡咯、聚噻吩等的出现使导电聚合物的种类不断出新,其用途也扩展到如导电材料、电极材料、催化材料以及太阳能电池等应用中,且已有部分产品实现了商品化。其中,聚噻吩因其良好的稳定性、易于制备、掺杂后具有良好的光电化学性能等特点而受到广泛关注。本文总结了几种合成聚噻吩及其衍生物的常见方法,包括化学氧化聚合法、电化学聚合法、金属催化偶联法、光致合成法、光电化学沉积法,以及近年来新发现的固相聚合法和酸催化聚合法,并简要介绍了各自的合成机理及优缺点。     

Gelation Dynamics and Mechanism(s) in Stereoregular Poly(Methyl Methacrylate)s

Chain conformation and gel structure of syndiotactic PMMA thermoreversible gels have been investigated using small angle neutron scattering (SANS). A double helix model for the chain conformation is proposed alongside a gel network model where the fibrils are formed by the proposed double helix and the junctions by the aggregation of 3 double helices. Preliminary results, also obtained by SANS, for stereocomplex gels prepared in bromobenzene are presented.     

Heterocyclic Poly(Bismaleimide)s. II. Synthesis and Characterization of New Poly(Ether-Bismaleimide)s Containing Parabanic Rings

Abstract

New poly(ether-bismaleimide)s containing parabanic rings were obtained by the nucleophilic substitution reactions of 1,3-bis(4-dichloromaleimido-phenyl)parabanic acid (4) with various bisphenols. The structures of the resulting polymers were confirmed by IR and elemental analysis. The polymers are soluble in aprotic dipolar solvents and showed lower thermal stability than other polymers without parabanic rings.     

Die vielen Gesichter des Poly(ethylenglykol)s

Today, a life without poly(ethylene glycol) is hardly imaginable. One encounters PEG in nearly every aspect of our daily needs: from cosmetics to hairstyling products and from medicines to food. Even in maritime military technology and the preservation of recovered cultural possessions PEG can be found. This article deals with the synthesis, the surprising properties, and the application of this structurally simple yet fascinating and important polymer.     

Excellent Redox Properties of Poly(thienylphenylamine)s

Triphenylamines with thienyl groups are electro‐oxidatively polymerized to yield the corresponding branched polymers on an electrode. The resulting polymers show significantly better redox properties, such as redox activity, catalytic activity, and conductivity when compared with for example the linear polymeric analog. The good properties of the branched polymers are based on the higher electronic conductivity (2–6 S/cm), since the branching provides multiple routes for charge carriers. The redox‐active polymers show high capacity (ca. 40 mC/cm²) and catalytic activity for the electron transfer of ferrocene on the electrode.     

Aliphatic Segmented Poly(ether ester amide)s Synthesized from Hexanediamine,Sebacic Acid and Poly(ethylene glycol)s

High molecular weight aliphatic segmented poly(ether ester amide)s(PEEAs) were synthesized via melt polycondensation and chain extension. An oligomeric polyamide(PA) terminated mainly with -COOH groups(HOOC-PA-COOH) was prepared from the reaction of nylon 610 salt with sebacic acid. Melt polycondensation of HOOC-PA-COOH with polyethylene glycol(PEG), such as PEG400, PEG600, PEG1000 and PEG1500, was conducted at 200℃, and several segmented PEEA prepolymers(PrePEEAs) were prepared. Chain extension of PrePEEAs was carried out at 190℃ using 2,2'-(1,4-phenylene)-bis(2-oxazoline) and adipoyl biscaprolactamate as combination chain extenders. Chain extended PEEAs(ExtPEEAs) were characterized by gel permeation chromatography(GPC), Fourier transform infrared spectrophotometer(FTIR), proton nuclear magnetic resonance(¹H NMR), differential scanning calorimetry(DSC), wide angle X-ray scattering(WAXS), thermogravimetry analysis(TGA), and tensile test. The ExtPEEAs exhibited M_n up to 98700, T_m from 164.2℃ to 176.1℃, initial decomposition temperature above 320.6℃, tensile strength up to 34.80 MPa, and strain at break from 111.92% to 353.12%. Aliphatic segmented PEEAs with good thermal and mechanical properties were prepared.     

超支化聚芳醚酮

超支化聚芳醚酮(HBPEKs)由于具有独特的理化特性和潜在的应用价值近年来备受关注.本文综述了HBPEKs最新的研究进展.HBPEKs可以由单单体和双单体方法来制备,文中重点介绍了HBPEKs的一些经典合成方法;同时,对HBPEKs的结构性能、表征手段和应用等进行了详细的描述;最后,指出了HBPEKs研究过程中需要解决的问题.     

Note Synthesis of New Poly(Amide-Hydrazide)s

Poly(amide-hydrazide)s were originally developed to give fibers of high modulus and high strength [1]. They were generally prepared 1) from dicarboxylic acid chlorides and aminohydrazides by low-temperature polycondensation [2,3]; 2) by the phosphorylation method [4, 5]; and 3) from dihydrazides with preformed amide linkages by low-temperature polycondensation [6]. These polymers were found to be thermally stable, but they showed poor solubility in polar aprotic solvents. In this paper we report the synthesis and characterization of some new poly(amide-hydrazide)s with azo groups in the backbone, which were introduced to improve solubility.