Shape Memory Of Hydrophobically Associated Hydrogels With High Strength And 3D Complex Deformation

Hydrophobically associated hydrogels?HA gels?are physical hydrogels formed by physical hydrophobic interactions as cross-linking points.In contrast to conventional chemically cross-linked gels,these hydrophobic HA gels have unique rheological behavior due to physical hydrophobic associations,which can be used to prepare PH,thermal response,and injectable hydrogels.On the other hand,such gels have a good self-healing ability due to the reversibility of hydrophobic association.At the same time,since the long side chain alkyl groups in the hydrophobic region can form microcrystalline regions,the temporary shape can be well fixed,and therefore,it is also the candidates for preparing shape memory functional materials.In this thesis,shape memory semi-crystalline HA gel,ion transfer printing shape memory hydrogel and near infrared responsive shape memory hydrogel were prepared by optimization of composition.The strengthening and toughening mechanism,self-recovery,self-healing performance,shape memory function and complex three-dimensional?3D?deformation were studied,the specific contents are as follows:?1?Shape memory semi-crystalline HA gel with high strength and toughness:The physical HPAAm-A11AUA HA gel was prepared by free radical micelle polymerization.The mechanism of gelation and the effects of different experimental conditions on the tensile mechanical properties of HA gel were investigated.Under the optimal preparation conditions,the HA gel shows that the tensile stress??_f?,tensile strain??_f?,elastic modulus?E?,fracture energy?W?and tearing energy???can reach 0.75 MPa,29.50 mm/mm,1016 kPa,17.53 MJ/m³ and 7540 J/m²,respectively.Furthermore,the HA gel shows rapid self-recovery property?at 60? for 2 min,toughness recovery⁹4%?and excellent self-healing properties?at 60? for 2 h,tensile stress recovery⁶4%,tensile strain recovery⁸5%?.In addition,the HA gel also possesses superior shape memory function?under the condition of 80 C,it can be recovered from the complex 3D deformation to the original 2D plane structure in 15 s?;?2?Ion transfer printing shape memory hydrogel and its complex 3D deformation:HPAAm-A11AUA-AAc HA gel with shape memory function was prepared by free radical micelle polymerization with acrylic acid?AAc?on the basis of HPAAm HA gel.The deformed HPAAm-A11AUA-AAc HA gel was dip-dyed with Fe³⁺ions on its surface,and then it was immersed in water bath of 80 ^oC to investigate deformation behaviors.The experimental results show that Fe³⁺can well control the deformation of the hydrogel,and can well realize the transition of the gel from simple two-dimensional structure to three-dimensional or more complex structure.Moreover,we have well realized the control of deformation behavior from the line to plane.?3?Near infrared responsive shape memory hydrogel and its controllable deformation:Based on the preparation of HPAAm-A11AUA HA gel,by introducing graphene oxide?GO?,the physical nanocomposite HPAAm-A11AUA/GO HA gel with near infrared response was prepared by free radical micelle polymerization.The gel's deformation is controlled by radiating the surface of the gel using near infrared light.The experimental results show that the hydrogel has a good response to the near infrared light.Besides,it can simultaneously memorize many times of deformation process and produce continuous deformation process.Moreover,we have well realized the control of deformation behavior from the point to plane.