Preparation Of 4D Printed Shape Memory Poly Aryl Ether Ketone And Its Tribological Study

As a highly sought-after engineering plastic,poly aryl ether ketone（PAEK）is widely utilized in aerospace,electronics,electrical appliances,and other specialized environments.However,the specificity of its molecular structure makes it difficult to dissolve and melt,thus limiting its processing potential through molding process.The molecular design enables modulation of the solubility and mechanical properties of PAEK materials,granting them unique properties（light curing）and excellent shape memory properties.In this paper,molecular design strategy was employed to synthesize a poly aryl ether ketone oligomer（PAEKO）with improved solubility,and cyanate ester was utilized as a crosslinking agent to fabricate PAEK with desirable form and performance.Secondly,to address the requirements of intricate components in engineering,photocuring 4D printing of PAEK was achieved through chemical modification and integration of active monomer.Finally,to investigate the correlation between shape memory and tribological properties,the friction behaviors of photocured PAEK at different temperatures were examined,and the potential of using photocured shape memory PAEK as an intelligent friction material was elucidated.The primary focus of this paper is as follows.（1）A soluble precursor of polyaryl ether ketone（PAEKP）was designed by utilizing monomers 4,4-difluorobenzophenone（DFBP）,hexafluorobisphenol A（BPAF）,and bisphenol acid（DPA）.After that,by adding the crosslinker bisphenol A cyanate（BPCE）,a thermosetting shape memory PAEK was prepared.The corresponding mechanical properties of the material were found to be adjustable by varying the amount of BPCE to regulate the degree of crosslinking,with the tensile strength reaching 47.3 MPa.More importantly,incorporating cyanate ester with a-CNO:-COOH ratio of 1:1 reduced the number of triazine rings between the PAEK molecular chains,resulting in improved toughness and better deformation above the transition temperature.The shape memory PAEK demonstrated excellent shape memory performance,with a shape fixation ratio（R_f）of up to 98%and shape recovery ratio（R_r）of up to 83%.（2）PAEK is a high-performance resin that is difficult to dissolve and melt,posing challenges for photocurable printing.To overcome this issue,photocurable PAEK oligomers（PAEKO）were developed by grafting hydroxyethyl methacrylate（HEMA）onto PAEKP.This modified molecular structure facilitated the dissolution of PAEKO in N-vinyl-2-pyrrolidone（NVP）,allowing for the preparation of a light-curable PAEK ink by adding the functional monomer polyethylene glycol diacrylate（PEGDA）.The ink containing 15 wt%PEGDA600exhibited good mechanical properties（42.6 MPa）,excellent printability（P_r=1.082±0.044）,and exceptional shape memory performance with Rf of 93-98%and Rr of>100%.The cross gripper printed by direct ink-write printing（DIW）was able to function in high-temperature（140°C）environments.（3）The tribological properties of light-cured shape-memory PAEK were investigated under varying conditions.It was observed that the coefficient of friction（COF）and wear rate decreased with an increase in load.In addition,the variations in coefficient of friction（COF）and wear rate with temperature changes demonstrated that the light-cured shape memory PAEK had adjustable friction properties.Based on the alteration in wear scar at high temperatures,a mechanism of shape reversion for wear self-compensation was proposed,and the intelligent response friction behavior of thermally responsive polymers was elucidated from the viewpoint of shape reversion and thermogenic phase transition.Finally,the tribological behaviors of the PAEK were significantly enhanced through physical blending modification,yielding a frictional coefficient and wear rate of 0.19±0.01 and 1.81×10^-4±0.53×10^-4 mm³/N·m,respectively.