邻苯二甲腈基联苯酚醛树脂中空微球的制备与性能研究

Preparation and Properties of Phthalonitrile Biphenyl Novolac Resin Hollow Microspheres

以苯酚及4,4′-二氯甲基联苯为单体,盐酸作催化剂经Friedel-Crafts烷基化反应,合成了联苯酚醛(BN)树脂,并在此基础上通过BN树脂和4-硝基邻苯二甲腈发生亲核反应合成了邻苯二甲腈基联苯酚醛(PBN)树脂,采用高温发泡法制备了邻苯二甲腈基联苯树脂中空微球.利用红外吸收光谱(FTIR)、核磁氢谱(~1H-NMR)、凝胶渗透色谱(GPC)、热失重(TG)以及扫描电子显微镜(SEM)等对制备的PBN树脂以及PBN中空微球进行了结构与性能表征.研究结果表明,采用自固化和固化剂固化的PBN树脂中空微球均已完全固化,2种固化产物中都形成了异吲哚啉和酞菁环结构,固化剂固化产物中还有三嗪环结构的形成.PBN树脂的自固化产物和固化剂固化产物固化物在1000°C氩气氛围残炭率分别为67%和70%,在600°C空气氛围残炭率分别为70%和47%.PBN树脂中空微球粒径分布范围为350~800μm,数均粒径和体积平均粒径分别为562和583μm,单分散指数为1.04.

Started from phenol and 4,4-dichloro-methyl-biphenyl, biphenyl-type novolac （BN） was synthesized by Friedel-Crafts alkylation reaction. Phthalonitrile biphenyl novolac （PBN） was then synthesized through nucleophilic substitution between 4-nitro-phthalonitrile and BN. Hollow PBN microsphere was prepared by high-temperature foaming for the first time. Structure and thermal properties of PBN and its cured products were examined by Fourier transform infrared spectroscopy （FTIR）, 1H nuclear magnetic resonance spectroscopy （1H-NMR）, gel permeation chromatography （GPC）, thermal gravimetric analysis （TG） and laser particle measurement, respectively. Structure of the PBN microspheres was characterized by optical microscopy and scanning electron microscope （SEM）. FTIR showed that nucleophilic substitution occurred for phenolic hydroxyl group and phthalonitrile was successfully grafted to BN backbone. Grafting rate of phthalonitrile was 53.63% calculated from 1H-NMR analysis. GPC analysis indicated that PBN and BN had similar dispersion index, indicating that nucleophilic substitution did not alter the molecular structure of BN main chain. FTIR analysis of the cured PBN indicated that the cure mechanism was dependent on the grafting rate of phthalonitrile. PBN underwent crosslinking through phenol-mediated reaction of its nitrile groups. By self-curing without curing agents, cured PBN formed rigid structures with isoindoline and phthalocyanine rings. With curing agents, triazine ring was formed in cured PBN, in addition to isoindoline and phthalocyanine rings. TG analysis showed that char yield of cured PBN was 67% by self-curing and it was 70% with curing agents used when curing was done in argon at 1000 ℃, while those figures became 70% and 47% at 600 ℃ in air. Hollow PBN microsphere was highly spherical as seen under SEM. The number average particle diameter was 562 μm and the volume average particle diameter was 583 μm, respectively, with a polydispersity index of 1.04.