Synthesis of polyimides by photoaddition of bismaleimides to benzene

Polyimides have been synthesized by the sensitized photoaddition of aliphatic and aromatic bismaleimides to benzene. The reaction involves 2+2 cycloaddition to give homoannular diene intermediate followed by Diels-Alder addition to give polymer. Proof of structure is based mainly on a comparison of infrared spectra with those of the corresponding polyimides prepared from maleic anhydride-benzene photoadduct and diamines. The very low solubility of the polymers indicates that crosslinking probably occurred during photolysis. All the polyimides appear to decompose by decyclization at about 420–485°C. Polymer yield was dependent on bismaleimide structure.     

Recent development of polyimides: Synthesis,processing, and application in gas separation

High-performance polymers have been concomitant with advanced technology for half a century. With the advancement of synthetic chemistry, the recent development of high-performance polymers has provided superior properties and enabled wide applications. This article reviews recent research progress in aromatic high-performance polymers. Particularly, we focus on the synthesis and processing of polyimides, as well as the application in gas separation membranes. We begin with a brief introduction to highlight important history and physiochemical characteristics of polyimides. Then, we review the various synthesis methods, followed by recent advances for improving processability. Finally, we evaluate the use of high-performance polymers in gas separation membranes with focus given to the key issues of plasticization and aging. Overall, the information presented herein provides an up-to-date overview of high-performance polymers, polyimides particularly, and serves as a guide for further research involving the applications in membrane technologies.     

New monomers and polymers via Diels-Alder cycloaddition

The series of new bis(naphthalic anhydrides) was prepared through Diels-Alder cycloaddition. The Diels-Alder cycloaddition was used as a synthetic route to new phenylated monomers as well as to polymers. All polymers synthesized revealed to be soluble in a wide range of organic solvents such as toluene, THF, chloroform, and displayed high thermostability. Therefore, they can be processed easily and are promising candidates for advanced coating systems as well as for electrooptical applications.     

Advances in cycloaddition polymerizations

Cycloaddition reactions have been employed in polymer synthesis since the mid-nineteen sixties. This critical review will highlight recent notable advances in this field. For example, [2 + 2] cycloaddition reactions have been utilized in numerous polymerizations to enable the construction of strained polymer systems such as poly(2-azetidinone)s that can, in turn, afford polyfunctional beta-amino acid derived polymers. Polymers have also been synthesized successfully via (3 + 2) cycloaddition methods utilizing both thermal and high-pressure conditions. 'Click chemistry'--a process involving the reaction of azides with olefins, has also been adopted to generate linear and hyperbranched polymer architectures in a very efficient manner. [4 + 2] Cycloadditions have also been utilized under thermal and high-pressure conditions to produce rigid polymers such as polyimides and polyphenylenes. These cycloaddition polymerization methods afford polymers with potential for use in high performance polymers applications such as high temperature resistant coatings and polymeric organic light emitting diodes.     

New processable polyaromatic ether–keto-sulfones curable by Diels-Alder cycloaddition

New Processable polyaromatic ether-keto-sulfones were prepared from the acid chloride of bis-m-carboxyphenyl acetylene (XII), isophthaloyl chloride (XX), diphenyl ether (XVIII), and 4,4′-diphenoxydiphenyl sulfone (XIX) in a Friedel-Crafts-type polymerization. These polymers were cured by Diels-Alder cycloaddition with 1,4-diphenyl-1,3-butadiene. The cured polymers showed an increase in T_g and in thermal and heat stabilities. The polymers form colorless, transparent, brittle films and can be cast into a glass fiber laminate. Both meta-and para-substituted acid chlorides of biscarboxyphenyl-1,3-butadiene yielded insoluble polymers under the same conditions but form processable polymers where combined with acetylene units in the polymer chain. Polymers that contained both acetylene and butadiene units were prepared but could not be cured by an intramolecular Diels-Alder cycloaddition reaction.     

Perfluoroalkylene-linked aromatic polyimides. II. Further property studies

The synthesis and general physical characteristics of the perfluoroalkylene-linked aromatic polyimides have been discussed in Part I. In this paper the hydrolytic, oxidative, and thermal stabilities of these polymers are compared with those of certain wholly aromatic polyimides. Comparative studies are also made on the effect of the fluoroalkylene chain on the glass transition temperatures. The polymer from di-(4-aminophenyl) ether and 1,3-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride has been studied in most detail and various mechanical and electrical properties of this polymer in film and solid molded form are discussed.     

Diels-Alder反应在硅橡胶工业及聚硅烷化学中的应用

本文总结了Diels—Alder反应在硅橡胶加工和聚硅烷合成方面的应用,其中包括:(一) 利用该反应合成了含多苯苯基或稠环的硅橡胶交联剂和耐热助剂;(二) 通过该反应建立了硅橡胶新型硫化体系,不外加催化剂;(三) 通过该反应合成了含多苯苯基或稠环的有机硅单体,进而制出许多新型聚硅烷;(四) 探讨了影响硅橡胶各种性能的因素及大芳基对聚硅烷性能的影响。     

Synthesis and properties of novel regioirregular polyimides from easily synthesized asymmetrical dichlorophthalimide monomers

New asymmetrical aromatic dichlorophthalimide monomers containing pendant groups (trifluoromethyl or methyl) were conveniently prepared from inexpensive and commercially available compounds. With these monomers, a new class of soluble polyimides with a regioirregular structure within the polymer backbone was obtained by the Ni(0)‐catalyzed polymerization method. The structures of the polymers were confirmed by various spectroscopic techniques. The polyimides displayed better solubility and higher thermal stability than the corresponding regular polyimides. In addition, fluorinated polyimides in this study had low dielectric constants ranging from 2.52 to 2.78, low moisture absorptions of less than 0.59%, and low thermal expansion coefficients between 10.6 and 19.7 ppm/°C. The oxygen permeability coefficients and permeability selectivity of oxygen to nitrogen of the films were in the ranges of 2.99–4.20 barrer and 5.55–7.50, respectively. We have demonstrated that the synthetic pathway for polyimides provides a successful approach to increasing the solubility and processability of polyimides without sacrificing their thermal stability. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3550–3561, 2007     

Synthesis and characterization of soluble fluorine‐containing polyimides based on 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene

The synthesis and properties of a class of soluble fluorine‐containing aromatic polyimides are described. Substituents of trifluoromethyl groups on the aromatic rings of paralinked aromatic ether diamine conferred the polymer prepared thereof with enhanced solubility, low‐moisture absorption, and low dielectric constants. The polyimides also exhibited exceptional thermal stability, good mechanical properties, and excellent hygrothermal resistance. These outstanding combined features ensure the polymers are desirable candidate materials for advanced microelectronics applications. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2581–2590, 2001     

Novel soluble thermally stable silane-containing aromatic polyimides with reduced dielectric constant

Bis(p-aminophenoxy)diphenylsilane (BPS), bis(m-aminophenoxy)diphenylsilane (BMS) and bis(5-amino-1-naphthoxy)diphenylsilane (BAS) as three silane-diamines were prepared by the reactions of 4-aminophenol, 3-aminophenol, and 5-amino-1-naphthol respectively, with dichlorodiphenylsilane in the presence of triethylamine. The related silane-containing polyimides were prepared by two-step polycondensation reactions of these diamines with three different aromatic dianhydrides. All the polymers were characterized and their physical and thermal properties were studied. The polymers showed high thermal stability while their solubility was greatly increased in polar aprotic solvents. Wide angle X-ray diffraction showed that all the polyimides were almost amorphous. Also their dielectric constants were decreased due to the incorporation of softening and low-polarizing siloxane units into the polymer backbone.     

Preparation and properties of azopolyimides-I

A new class of aromatic and heterocyclic polyimides were synthesized from benzothiazoleamines benzidine, 4,4′-diaminodiphenyl ethane and 4,4′-diamino diphenyl sulfone with 4,4′-azodipthalic anhydride and/or pyromellitic dianhydride. The synthesis involved the reaction of the dianhydride with the respective diamine to yield an intermediate, soluble, open chain precursor polymer, the polyamic acid, which on cyclodehydration yielded the less soluble, heat resistant polyimides. All these polyimides were characterized by IR and NMR. Solubility, density, viscosity, and thermal stability of these polymers were also studied.     

光致发光聚酰亚胺研究进展

聚酰亚胺是一类重要的高性能高分子材料,具有优异的热性能、机械性能、电学性能和尺寸稳定性等,同时具有良好的结构可设计性,已逐渐成为有机光电领域的研究热点.然而,传统聚酰亚胺材料一般不发光,文献中有关发光聚酰亚胺的研究并不多.同时,所报道的荧光量子产率普遍较低,极大地限制了其作为发光功能层在有机光电器件领域的应用.为了更好地了解聚酰亚胺发光的规律,拓展高性能聚酰亚胺材料在有机发光器件中的应用领域,本文介绍了聚酰亚胺光致发光的机理,综述了国内外有关光致发光聚酰亚胺的研究进展,总结了提高聚酰亚胺荧光量子产率的方法,并对未来高性能高效发光聚酰亚胺材料的研究方向做了展望.     

Synthesis and properties of alkylene-linked aromatic polyimides

Alkylene-linked aromatic polyimides were prepared from a family of new dianhydride monomers and aromatic diamines. The dianhydrides were synthesized by Friedel-Crafts catalysis of the condensation of ditertiary alcohols with o-xylene, subsequent oxidation of the aryl methyl groups to carboxy, and finally, dehydration of the ortho-carboxy substituents to anhydride groups. Alkylene-linked aromatic polyimides, with up to 8 methylene groups in the polymer chain, are stable to 400°C in air and can be extruded or compression-molded at 300°C. In addition, these polymers are soluble in solvents within the solubility parameter range of 10.4 ± 1.2.     

New polyimides incorporated with diphenylpyrenylamine unit as fluorophore and redox‐chromophore

A series of novel polyimides based on N,N‐di(4‐aminophenyl)‐1‐aminopyrene and aromatic or alicyclic tetracarboxylic dianhydrides were synthesized. The polymers exhibited good solubility in many polar organic solvents and could afford robust films via solution casting. The polyimides derived from aromatic dianhydrides exhibited high thermal stability and high glass‐transition temperatures (333–364 °C). Cyclic voltammetry studies of the polymer films showed that these polyimides are both p and n dopable and have multicolored electrochromic states. For the polyimides derived from alicyclic dianhydrides, they revealed a strong blue‐light emission with high fluorescence quantum yields (?_PL > 45%) and a marked solvatochromic behavior. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis and properties of polyimides from 4,4′-binaphthyl-1,1′,8,8′-tetracarboxylic dianhydride

4,4′-Binaphthyl-1,1′,8,8′-tetracarboxylic dianhydride was synthesized from 4-chloro-1,8-naphthalic anhydride and polymerized with aromatic and pliphatic diamines in m-cresol or N-methyl-2-pyrrolidinone (NMP). The polyimides, except for two derived from p-phenylenediamine and hydrazine, are soluble in 1,1,2,2-tetrachloroethane and NMP. Their intrinsic viscosities ranged from 0.36 to 2.20 dL/g. The polymers showed excellent thermal and thermooxidative stabilities and displayed weak glass transition temperatures. Young's moduli of some polymer films were in the range of 2.5 and 5.4 GPa at 30°C. The aliphatic polyimides exhibited a stronger fluorescence than the aromatic polyimides. © 1995 John Wiley & Sons, Inc.     

Aromatic polypyromellitimides from aromatic polyamic acids

Aromatic diamines react with pyromellitic dianhydride in solvents such as dimethyl-acetamide to form solutions of high molecular weight polyamic acids. These soluble polymers can be converted to insoluble aromatic polyimides. The aromatic poly imides exhibit zero strength temperatures above 700°C. and possess excellent thermal and oxidative stability. The stability characteristics of films and the relation of chemical structure to thermal and hydrolytic stability and to polymer properties such as crystallinity are described.     

Hydrolytic degradation and thermooxidative stability of polyimides based on 3,5-diaminodiphenyl oxide and 2-methyl-3,5-diaminodiphenyl sulfide

For a number of new polyimides prepared from 3,5-diaminodiphenyl oxide, 2-methyl-3,5-diaminodiphenyl sulfide, and various dianhydrides of aromatic tetracarboxylic acids, the hydrolytic stability in DMF and 96% H₂SO₄ and the thermooxidative stability in the bulk have been studied. Hydrodynamic techniques have been employed to determine the molecular parameters of these polymers at various stages of degradation. It has been shown that the polymers under study form stable solutions in DMF but turn out to be unstable in 96% H₂SO₄ even at room temperature. Degradation accompanies dissolution of the polymer. The correlation between the chemical structure of polymer molecules and their hydrolytic stability in both solvents has been established. It has been demonstrated that the majority of the said polyimides are stable in the solid state at temperatures up to 400°C and marked degradation begins only above 500°C.     

碳纳米管上分子印迹微反应器的构建及催化Diels-Alder反应研究

分子印迹聚合物（MIP）在合成与催化方面的应用受到越来越多的关注.传统的本体聚合生成的聚合物往往具有活性中心的利用率低、活性中心不均一、底物难以到达等问题.由于纳米材料具有很高的比表面积,将MIP制备成纳米级别的材料将有可能解决这些问题.本研究的目的是在纳米材料上构建分子印迹微反应器(MIM).通过多壁碳纳米管(MWNTs)上羟基的酯化反应在碳纳米管表面枝接双键,以蒽和马来酸的加成反应产物为模板分子,甲基丙烯酸(MAA)为功能单体,乙二醇二甲基丙烯酸酯(EDMA)为交联剂,通过微波辐射聚合在碳纳米管表面枝接一层厚度约为30 nm 的分子印迹催化剂. 该催化剂对蒽和马来酸的加成反应具有明显的催化作用,反应开始后的180min内,催化反应速率是不加催化剂反应速率的1.77倍. 催化动力学遵守Michaelis-Menten方程,催化反应最大速率（vmax）为0.713 umolL-1S-1,米氏常数（KM）为17735.24 umolL-1.     

Soluble and Colorless Polyimides from Alicyclic Diamines

Abstract

A series of novel polyimides was synthesized from alicyclic diamines and various aromatic dianhydrides by one-step polymerization in m-cresol without a catalyst. The polymerization was conducted for 4 hours with refluxing, which was enough to obtain the polymers with high molecular weight. The inherent viscosities of the resulting polyimides were in the range of 0.30 ～1.29 dL/g. The prepared polyimides showed excellent thermal stabilities and good solubility. All the polymers were readily soluble in common organic solvents such as chloroform, tetrachloroethane (TCE), dimethylacetamide (DMAc), etc and the glass transition temperatures were observed at 199 to 311°C. UV-visible spectra were obtained to measure the transparency of polymer films. All the polymers showed high transmission above 90% in the wavelength of 400 ～700 nm.     

Solid-phase synthesis of polymers using the ring-opening metathesis polymerization

We report a general method for the solid-phase synthesis of polymers via the ring-opening metathesis polymerization (ROMP). The method involves polymerization in solution to form a block copolymer, immobilization of the polymer via reaction of one block with a resin-bound functional group, modification of the other block, and liberation of the polymer from the resin. We demonstrated the utility of this approach by generating a block copolymer with an N-hydroxysuccinimidyl ester-substituted block (for on-resin functionalization) and a maleimide-substituted block (for conjugation to the resin). We showed that the Diels-Alder reaction can be employed to immobilize the polymers and that amines of diverse structure can be used to modify the resin-bound polymers. The reversibility of the furan-maleimide Diels-Alder adduct was exploited to liberate the polymer from the support. Specifically, treatment of the resin with cyclopentadiene resulted in complete polymer release. The resulting polymers are functional: they were as potent in assays with the lectin concanavalin A as polymers generated by traditional solution routes. We anticipate that this method can be used for the rapid synthesis of diverse polymers via ROMP.