The Molecular Design And Performance Study Of Poly (Aryl Ether Ketone) Containing Naphthalene

Poly(aryl ether ketone)(PAEK) is a kind of high-performance polymer with excellent mechanical property, heat resistance and chemical stability, which has already been widely used in many high-tech fields such as aerosapace, national defense technology,biomedicine and energy. However, it still suffers the problems such as poor solubility and machinability. Thus design and synthesis of novel PAEK with good comprehensive properties is very imprortant. Naphthalene-based PAEK gains extensive research in the past 20 years. Firstly, the introduction of naphthalene ring makes the polymer more rigid and improves Tg of the polymer. Secondly, the introduction of naphthalene with functional groups can make the material possess some unique physical and chemical properties.Thirdly, the polymer can be further modified by the high reaction activity of naphthalene ring.With the scientific and technologic progress, functionalization is becoming one of the trends in developing of polymers. Design and synthesis of polymers with special functional groups is an important mean to bring out funtionalization. Nowadays, there are many studies on the funcionalization of PAEK, such as sulfonation, carboxylation,quaternization, nitrification, etc. Among them, sulfonated PAEK gains the most extensive researches and applications, for example, in selective separation and proton exchange membrane(PEM). Especially in fuel cell, because of the high confuctivity, low methanol permeability and swelling, sulfonated PAEK has good application prospect.This work is aiming to design and synthesize novel nathphalene-based PAEK with different functional groups. And then study the properties of the functional polymers and explore their application foreground in new fields.Firstly, we synthesized a fluorine monomer containing methoxy:1,5-bis(4-fluorobenz-oyl)-2,6-dimethoxynaphthalene. Then PAEK with methoxy(PAEK-OCH3) and hydroxyl(PAEK-OH) were obtained through polycondensation and demethylation. In Chapter 2, side-chain-type sulfonic PAEK(PAEK-SO3H-x) with different Ds were syntheszised by reacted PAEK-OH with 1,4-butanesultone. The structure the polymers were confirmed by 1H NMR. The properties of the proton exchange membrane based on PAEK-SO3H-x were characterized. The results showed that this kind of PEM possessed excellent performance. This side-chain-type PEM achieved high proton conductivity as well as relatively low methonal permeability. They also possessed satisfactory mechanical and thermal stability. The results illustrated this side chain type sulfonated PAEK containing naphthalene could be used as a kind of proton exchange membrane material with good comprehensive performance.The introduction of –SO3- enabled the material to have remarkable ability to absorb water, meanwhile it could exist stably in high humidity environment. So we inferred that this kind of material had humidity response. In Chapter 3, firstly, we synthesized a series of naphthalene-based PAEK containing sulfobutyl sodium salts(PAEK-SO3Na) using the method described in the last chapter. The microstructure and water adsorption properties of PAEK-SO3 Na with different Ds were characterized in detail. Then we fabricated the resistive-type humidity sensors with these polymers and investigated the influence of Ds on the humidity sensing properties. The sensors showed high sensitivity and responsiveness among the whole humidity range. The response time could reach the polymeric humidity sensor application demand. These demonstrated that this side-chain-type SPAEK have a potential use as humidity sensitive materials. However, the PAEK-SO3Na-based humidity sensors suffered a shortcoming of high humidity hysteresis.Keeping the goal to minify the humidity hysteresis of the sensors in the last chapter,we modified the material by blending nano-silica with PAEK-SO3 Na. In Chapter 4, we prepared the composite membranes with different silica contents. IR and EDS results illustrated the successful preparation of the composite. Then we fabricated the resistive-type humidity sensors based on the coposite and investigated the humidity sensing properties. Within an appropriate range of silica content, the sencors showed a good sensitivity and responsiveness. Furthermore, the humidity hysteresis decreased remarkably with the increase of silica content. The humidity hysteresis of PAEK-SO3Na-5% could almost be negligible. Meanwhile, the addition of Si O2 could shorten the response time and improve the performance of the humidiy sensor.In Chapter 5, we explored a novel functional PAEK containing thermally labile Boc groups by reacting PAEK-OH with Boc2 O. The structure was confirmed by 1H NMR spectra. The thermal properties of the polymers were characterized by DSC and thermogravimetry coupled time-resolved mass spectrogram(TG/MS). The resulting polymers exhibited relatively high Tg because of the existence of a rigid naphthalene moiety. The Boc groups thermally decomposed and in-situ generated CO2 and isobutene gases as the foaming agents. Then closed microcellular porous membranes with a wide range of expansion ratio were obtained by a simple thermal treatment, without using any other physical or chemical foaming agents. Furthermore, we investigated the relationship between the foaming temperature and the morphology of membranes in detail by using density measurement and scanning electron microscopy.