Aromatik poliimid ve poliamidler

Abstract

Günümüzde yeni ve üstün özellikli malzemelere olan ihtiyaç ve buna cevap verebilecek malzeme arayışları yoğun bir biçimde devam etmektedir. Bu alanda yapılan araştırma ve geliştirme çalışmalarının hedefi, üstün özellikli yeni malzemelerin üretimine imkan verecek farklı kimyasal yapılardaki monomer ve polimerlerin tasarımı, sentezi ve karakterizasyonuna yöneliktir. Bu çalışmada, işlenebilir, çözünebilir ve termoplastik yeni poliimidlerin ve poliamidlerin sentezi ve karakterizasyonu amaçlanmıştır. Bu amaçla, yukarıda sözü edilen özellikleri taşıyacağı düşünülen ve literatürde bugüne kadar sentezi gerçekleştirilmemiş olan üç yeni aromatik diamin monomeri, 1,1'-sülfonil-bis-(2,5-dimetil-3-amino) benzen (DATMDS), bis-(3-aminofenil) fenilfosfin oksit (m-DATPPO) ve 1,3- Bis-(3-aminobenzoil)-5-tersiyer bütil benzen (5-t-but-DABB) sentezlenmiş ve FTIR, NMR, MS ve elementel analiz gibi enstrümental analiz teknikleriyle karakterize edilmişlerdir. Bu yeni monomerlerden, ticari olarak bulunan 4,4'-oksidiftalik anhidrit (ODPA), 4,4'-hekzafluoroizopropiliden-bis(ftalik anhidrit) (6FDA), 3,3', 4,4'- benzofenon tetrakarboksilik dianhidrit (BTDA), 3,4,3', 4'-bifenil tetrakarboksilik dianhidrit (BPDA) ve piromellitik dianhidrit (PMDA) gibi çeşitli dianhidritlerle termal çözelti imidizasyonu tekniğiyle homo ve kopoliimidler sentezlenmiştir. Yine bu monomerlerden DATMDS ve m-DATPPO ile ticari olarak bulunan tereftalik asit (TPA), izoftalik Asit (İPA), 5-tersiyer-bütil-izoftalik asit (5-t- but-İPA), 4,4'- dikarboksi difenilsülfon (DCDS), 1,4- dikarboksi siklohekzan (DCC), ve 2,6- naftalen dikarboksilikasit (NDA) gibi çeşitli diasitlerle doğrudan polikondenzasyon tekniğiyle poliamidler sentezlenmiştir. Elde edilen poliimid ve poliamidlerin intrinsik viskoziteleri, çözünürlükleri, FTIR spektrumları, NMR spektrumları, DSC ve TGA ile camsı geçiş sıcaklıkları ve termooksidatif kararlılıkları ile karakterizasyonları yapılmıştır.

During the last two decades, in parallel to the demands from the industry, material performance specifications are continuously upgraded and new criteria are added. The growing need for new and high performance materials has triggered the search for materials that will fulfill the standards. The research and development activities in this field are mostly geared to the design, synthesis, and characterization of new monomers and polymers of different chemical structures which will meet the requirements and enable the production of new high performance materials. Aromatic polyimides are of high interest for engineering and microelectronic applications due to their unique property combinations.There are many applications for polyimides including high temperature insulators and dielectrics, high temperature coatings, adhesives, and matrices for high performance composites. Their exceptional thermal and oxidative stability and solvent resistance are complemented by excellent mechanical and electrical performance, dimensional stability over a wide temperature range, and resistance to high energy radiation. However, insolubility in common and/ or environmentally acceptable solvents and high glass transition temperatures make these systems difficult to process. Therefore much effort has been spent on synthesizing processable, tractable polyimides without compromising desired properties.To accomplish this, the incorporation of flexible bridging units into the rigid polyimide backbone has been widely used. Wholly aromatic polyamides (aramides) are another class of polymers which show promise of meeting many of the requirements for high-temperature resistant polymers. They exhibit a number of useful properties such as high thermal stability, chemical resistance, low flammability, and they have excellent mechanical properties as fibers. They find applications in uses like high-temperature filtration, protective clothing, conveyor belting, electrical insulation and reinforcement where high temperature and wear resistant fiber-based materials are needed. However, the versatile applications of these polyamides have generally been reduced by the high crystallinity and limited solubility in common solvents. Introduction of flexible bridging groups and distortion of symmetry are the most frequently used methods to increase solubility and decrease crystallinity. XV The objective of this study was to synthesize a series of processable, tractable, soluble and thermoplastic polyimides and polyamides without compromising the desired properties by incorporating flexible bridging units, meta linkages and bulky bridging groups between the aromatic rings to increase the solubility. To accomplish this goal, three new aromatic diamine monomers, namely,1,1'-sulfonyl-bis- (2,5-dimethyl-3-amino) benzene (DATMDS), bis-(3-aminophenyl) phenyl phosphine oxide (m-DATPPO) and 1,3- bis-(3-aminobenzoyl)-5-tertiary-butyl benzene (5-t-but-DABB) were synthesized in our laboratories. The structures of the diamine monomers were confirmed by instrumental analysis techniques using FTIR, NMR, MS, and elemental analysis. H,N H,N (f\) NH, m-DATPPO H2N Jjl NH, 5-t-but-DABB The diamine monomers were than used in the synthesis of polyimides by two step thermal solution imidization technique using commercially available dianhydrides, 4,4'-oxydiphthallic anhydride (ODPA), 4,4'-hexafluoro isopropylidene-bis(phthallic anhydride) (6FDA), 3,3',4,4'-benzophenone tetracarboxyllic dianhydride (BTDA), 3,4,3', 4'-biphenyl tetracarboxyllic dianhydride (BPDA) and pyromellitic dianhydride (PMDA). The synthetic route is schematically represented in Scheme 1. Polyimides synthesized are summarized in Table 1 The structures of the polyimides were confirmed by FTIR and 1H-NMR spectra. XVI 1. Polyamic acid formation cosolvent system: NMP/ODCB 85:15 room temp., 24 hrs, N2 atm. Poly (amic acid) 2. Solution imidization cosolvent system: NMP/ODCB 85:15 180°C,24hrs,N2atm. O O II II Ar_/Xv o o Polyimide p4« [t^!-Q X= C,0,C(CF3)2,- a b c d Scheme 1 The synthesis of polyimides by two step thermal solution imidization technique XVll Using DATMDS (1) as diamine, soluble polyimides were obtained (S 1 and S 2) when ODPA (5b) and 6FDA (5c) were used as dianhydrides, whereas precipitation occured during cycloimidization step when BTDA (5a), BPDA (5d), and PMDA (4) were used and soluble homopolyimides could not be obtained. By incorporating various amounts of 6FDA (5c) into the dianhydride portion as comonomer, soluble copolyimides were obtained (S 3,2 (50:50), S 3,2 (75:25), S 4,2 (50:50), S 4,2 (75:25), and S 5,2 (50:50). The homo and copolyimides prepared were all soluble in N-methyl pyrrolidone (NMP), N,N-dimethyl acetamide (DMAc), and chloroform and all can be cast into transparant and flexible films from their solutions. Using m-DATPPO (2) as diamine, soluble homopolyimides were obtained with all of the dianhydrides (P 1, P 2, P 3, P 4, and P 5). All the polyimides were soluble in N-methyl pyrrolidone (NMP), N,N-dimethyl acetamide (DMAc), and chloroform with the exception of P 4 and P 5 which showed limited solubility in chloroform. All can be cast into transparant and flexible films from their solutions. Soluble polyimide synthesis using 5-t-but-DABB (3) as diamine and BTDA (5a) and 6FDA (5c) as dianhydrides resulted in precipitation during cycloimidization step and the polyimides obtained were insoluble (C 1 and C 2). Intrinsic viscosities and thermal analysis results of the polyimides synthesized are given in Table 2. The diamine monomers were also used in the synthesis of polyamides by direct polycondensation technique using commercially available diacids, terephthallic acid (TPA) (6), isophthallic acid (İPA) (7), 5-tertiary-butyl- isophthallic acid (5-t-but-İPA) (8), 4,4'- dicarboxy diphenylsulfone (DCDS) (11), 1,4- dicarboxy cyclohexane (DCC) (9)^ and 2,6- naphthalene dicarboxyllic acid (NDA) (10). The synthetic route is schematically represented in Scheme 2. Polyamides synthesized are summarized in Table I.The structures of the polyamides were confirmed by FTIR and 1H-NMR spectra. All the polyamides synthesized were soluble in polar aprotic solvents like N- methyl pyrrolidone (NMP), N,N-dimethyl acetamide (DMAc), and insoluble in chloroform, toluene and tetrahydrofuran (THF). All can be cast into transparant films from their solutions.