Preparation And Characterization Of A Crosslinkable Sulfoxide Containing Poly(Aryl Ether Sulfone)

Plastic is a kind of organic synthetic polymer material which is widely used in the fields of social production and social living.Special engineering plastics,one of the high-performance plastics,have attracted extensive attention because of their unique and excellent thermal and mechanical properties.Among them,poly(aromatic ether sulfone)has better hydrolysis-resistance,flame retardance,processability,higher glass transition temperature compared with other special engineering plastics due to the simultaneous presence of rigid groups(benzene ring,sulfone group,etc.)and flexible groups(ether linkage,etc.)in the molecular segment.In particular,the biphenyl-type poly(aromatic ether sulfone)synthesized by biphenyl bisphenol and dihalogen monomer exhibits superior performances,including mechanical properties,thermal properties,hardness,and creep-resistance than other poly(aromatic ether sulfone)(bisphenol A,bisphenol S)owing to the introduction of biphenyl structure in the molecular backbone.For example,the heat-resistance temperature of the polyphenylsulfone(PPSU)is up to 180 ℃,and the maximum service temperature is as high as 220 ℃ in the case of short-term use.Compared with other special functional engineering plastics,polyaryl ether sulfone polymers have many excellent properties.For example,compared with polyaryl ether ketone,polyaryl ether sulfone polymers have good fluidity in high temperature environment,so that polyaryl ether sulfone polymers exhibit excellent processing properties.However,as a typical type of amorphous polymer,it has poor solvent-resistance.Especially in high temperature environments,organic solvents can cause polymer cracking by promoting residual stress,affecting the use and life of product.Therefore,improving the solvent-resistance of poly(aromatic ether sulfone)has been the focus of researchers.Among the numerous modification methods,the introduction of a crosslinkable reactive group into the molecular segment will be a common and effective way.Before crosslinking,the polymer containing a reactive group is highly soluble in organic solvents,which makes it easy to process;aftercrosslinking,the crosslinked network structure formed by chemical reaction of the crosslinkable reactive group leads to excellent solvent-resistance.In this paper,we selected 4,4’-dihydroxybiphenyl as the bisphenol monomer,4,4’-dichlorodiphenyl sulfoxide and 4,4’-dichlorodiphenyl sulfone as the dihalogen monomer.By controlling the ratio of the two dihalogen monomers,a series of poly(aromatic ether sulfone)polymers containing novel active sulfoxide groups were synthesized through a nucleophilic substitution reaction.The test results show that although the introduction of sulfoxide groups can increase the flexibility of the polyphenylsulfone(PPSU)molecular segment,making its thermal properties worse.Nevertheless,even the polymer with a sulfoxide content of 100% still possesses a high glass transition temperature of 180 ℃ and a 5% weight loss temperature of above 380 ℃.However,there are currently few studies on the cross-linking behavior of sulfoxide groups.To further investigate the cross-linking mechanism of sulfoxide groups,the optimized polymers with a sulfoxide content of 0% and 40% were subjected to heat treatment and salt-added heat treatment,which is expected to explore the crosslinkability of sulfoxide and the effect of the temperature,ion on the cross-linking degree of sulfoxide group.It was finally proved that the sulfoxide group can be crosslinked at a certain temperature,and the incorporation of the ferric ion will further promote the crosslinking of the sulfoxide group.