Synthesis And Properties Of Shape Memory Poly(aryl Ether Ketone)s Containing Flexible Alkyl Chains

Poly(aryl ether ketone)s have attracted lots of attention from researchers because of its excellent thermal stability,corrosion resistance,mechanical properties and high glass transition temperature.However,there are little work has been reported on the shape memory properties of poly(aryl ether ketone)s materials.Shape memory polymers as a kind of functional materials has been widely concerned since the 1980 s and developping rapidly which has paly an important role in aerospace,biomedical,packaging materials,structural components.etc.It is a necessary smart material for the development of new technologies in the future.The purpose of this article to prepare a new type of thermoplastic poly(aryl ether ketone)s material which can behave good shape memory properties under high temperature and new photo-thermo staged-responsive behaviors by molecular designing and maintain its outstanding properties at the same time.Firstly,according to the structural features of alternating soft and hard segments of the shape memory polymers,a new flexible monomer-1,14-tetradecanediol p-fluorobenzoic acid diester was designed and synthesized,and 3,3,5,5-tetramethyl-4,4-bisphenol and 4,4-difluorobenzophenone were used as reaction materials.The shape memory poly(aryl ether ketone)s containing different flexible monomers were prepared by nucleophilic substitution reaction and its structure and properties were characterized and studied.It can be see that polyaryletherketones poly(aryl ether ketone)s containing different flexible monomers both behave excellent mechanical properties and thermal properties,but with the increase of flexible monomer content,the thermal properties of polymers performed a significantly reduced.The DMA testing results show that the polymers exhibited a certain shape memory ability,but the shape recovery rate needs to improve further.In addition,polymers containing more flexible monomers show better shape memory properties.Next,the carboxyl structure was introduced into poly(aryl ether ketone)s with different flexible monomers.Aim to provide physical cross-linking points on the shape memory process using hydrogen bonds between the molecular chains formed by introducing a carboxyl group,thereby improving shape memory behaviors of the polymers.The test results show that the polymers are little different in mechanical properties and thermal properties from the previously synthesized polymer and the variation law of the properties is consistent.However,the polymers with the carboxyl structure have a significant improvement in shape recovery rate which is about 12% higher than the poly(aryl ether ketone)s without carboxyl.Finally,the photo-responsive group azobenzene molecule was introduced into the flexible poly(aryl ether ketone)s with the carboxyl structure main chains in order to impart additional stimulating response behavior to the polymer and prepare a kind of shape memory poly(aryl ether ketone)s contain azobenzene groups with dual stimuli response behaviors.It has been found by testing that polymers containing azobenzene groups still exhibit good mechanical and thermal properties and maintain outstanding thermal induced shape memory properties.What's more important is that the polymer can occur large deformations under ultraviolet light and this photo response behavior is we expect.Moreover,the response speed and deformation ability for UV light of polymer films containing different azobenzene groups are also discussed and summarized.The photo-response speed and deformation ability of polymers with different azobenzene contents were investigated.The results show that the poly(aryl ether ketone)s polymers with azobenzene structure in the main chain can undergo large deformation under ultraviolet light,and has excellent thermo-induced shape memory properties and photodeformation characteristics.At the same time,the polymers both perform good mechanical properties and thermal properties.