The Molecular Design And Performance Study Of Poly(Ether Ether Ketone) Grafted With Sulfoalkylamine

Poly(ether ether ketone)is a kind of special engineering plastic,which has many outstanding properties,including high temperature resistance,chemical stability,corrosion resistance,excellent mechanical properties,dimensional stability,good insulation and so on.Therefore,it has been applied to various fields,such as aerospace aviation,defense science and technology,biomedicine,energy and environmental protection,electrical and electronic,automotive manufacturing and other fields.In order to improve the performance of poly(ether ether ketone),expand its use range and solve some problems such as poor solubility of some polymers,functionalization has become an effective method in decades.There are many active sites on the benzene ring for tethering many special functional groups,such as sulfonic acid groups,carboxyl groups,quaternary ammonium groups and nitro groups.Among these polymers containing functional groups,sulfonated poly(ether ether ketone)has received a lot of attention.Another useful approach for polymer modification is cross-linking,which is divided into physical and chemical cross-linking.Chemical crosslinking can achieve the purpose of improving the strength,heat resistance,abrasion resistance,solvent resistance and other properties through using the functional groups in the polymer system or introducing cross-linking agent.This work is aiming to synthesize a new type of sulfonated poly(ether ether ketone)containing sulfoalkylamine,and then improve the properties by ionic cross-linking and explore its applications in fuel cells and humidity sensors.First of all,we synthesized 4-aminophenyl hydroquinone(APHQ),which is a bisphenol monomer with amino groups on the side groups,and then polymerized with methylhydroquinone and 4,4'-difluorobenzophenone.By adjusting the ratio of APHQ to methylhydroquinone,a series of poly(ether ether ketone)s NPEEK-x with different contents of amino groups were obtained.In the third chapter,a series of side-chain-type sulfonated poly(ether ether ketone)polymers with different contents of sulfonic acid groups(SNPEEK)were prepared by reaction between NPEEK-x and 1,4-butanesulfonate.The results of~1H-NMR showed the polymer was synthesized successfully.The results of TEM showed that the SNPEEK-x polymer could form a distinct hydrophilic/hydrophobic phase separation,which made SNPEEK-x polymer have high proton conductivity.As the proton exchange membrane in direct methanol fuel cell(DMFC),SNPEEK-x membranes exhibit good water absorption,acceptable swelling rate and methanol permeability,indicating that under the appropriate contents of the sulfonic groups,the SNPEEK-x membranes meet the requirements of the proton exchange membrane in DMFC.Due to the introduction of a large number of sulfonic acid groups into the SNPEEK-x polymer,in order to maintain dimensional stability while maintaining high proton conductivity and improve the alcohol resistance of the polymer membrane,we chose the SNPEEK-1.0 polymer with the highest conductivity and the highest swelling ratio as the base polymer and used the interaction between protonated imidazole and sulfonic acid group,putting the imidazole group based around the sulfonic acid group,then CSNPEEK-x crosslinking proton exchange membranes were prepared through means of double bond polymerization by UV in situ initiating.The experimental results showed that the thermal stability and dimensional stability of these crosslinked membranes were improved significantly.Comparing the cross-linked membrane of CSNPEEK-x and SNPEEK-1.0membrane,it was worth mentioning that the methanol permeability reduced by two orders of magnitude,which greatly improved the alcohol resistance of the polymer membrane.In the third chapter,we found that SNPEEK-x had good water absorption capacity and high proton conductivity,so we explored the application of SNPEEK-x in the field of humidity sensors.SAXS results showed that all SNPEEK-x could form a distinct phase separation between hydrophilic and hydrophobic domains.The size of the ion clusters formed by the aggregation of sulfonic acid groups increased with the content of sulfonic acid groups increasing.This is consistent with the TEM result in the third chapter.The results of the humidity-sensing measurements of SNPEEK-x showed that the response time of the SNPEEK-x was about 2-3 s and the SNPEEK-x had good sensitivity and good long-term stability.