Bionic Structure Design And Fabrication Of Temperature Sensitive Smart Hydrogels

Materials are not only the material cornerstone of production and life,but also the embodiment of human science and technology development.As a typical intelligent material,smart hydrogel has excellent water absorption/water retention performance,high mechanical strength,diverse intelligent response mode and good biocompatibility,and has broad application prospects.Among them,the temperature-sensitive smart hydrogel has been widely used in important fields such as flexible actuators,artificial muscles,carrier transport release,intelligent surfaces and biological organs due to its simple stimulation form,high response efficiency and excellent mechanical strength.However,the wide application of temperature-sensitive smart hydrogels has raised a higher demand for high load capacity,diversified response,high response sensitivity,precise structural form,diversification and controllability.The comprehensive performance such as self-driving deformation is also a technical problem that it urgently needs to solve.Many plants in nature provide high-efficiency self-driven deformation and motion under the premise of good mechanical strength,which provides an important bionics enlightenment for the solution of the temperature-sensitive smart hydrogel bottleneck problem.Among them,the yellow stalk seed awns use the precise microscopic structure difference between the cell fibers,and the water absorption and release as the main driving force to achieve excellent self-driving deformation.In this paper,based on its microstructural characteristics and self-driven deformation function,the bionic doublelayer structure model and the bionic layered network structure model were designed to guide the design of bionic temperature-sensitive intelligent hydrogel.preparation.Nisopropyl acrylamide is used as monomer,XLG type synthetic lithium magnesium silicate is used as cross-linking agent,nano-wood pulp cellulose is used as reinforcing phase,and high mechanical properties are prepared by "one-step" mold forming technology and 3D printing technology.Temperature-sensitive bionic smart hydrogel with high strength,high molding efficiency,high preparation accuracy and high intelligent response.Through the analysis of material properties,mechanical strength and self-driven deformation,the corresponding deformation mechanism is revealed,which provides a way to solve the bottleneck problem of high-mechanical strength,high response rate and high-precision molding preparation of temperature-sensitive smart hydrogel.An effective new method of bionics.The main research contents and conclusions of this thesis are as follows:(1)The seed of the yellowback grass has the function of self-driven spiral deformation under humidity conditions,and its microstructure exhibits a multi-layered porous helical torsion structure,and the angle between the inner and outer fibers of the spiral torsion and the axis of the spiral is different,and The outer layer fiber has high water absorption performance and low water retention performance;the inner layer fiber has low water absorption performance and high water retention performance,and the two layers cooperate with each other to cause anisotropic reversible spiral motion between the inner and outer layers.(2)Based on the self-driven deformation mechanism of the seed awning of the yellow back grass,the bionic double-layer structure model and the bionic layered network structure model were constructed respectively to provide reference for the design of the temperature-sensitive intelligent hydrogel bionic structure.(3)Based on the biomimetic two-layer structure model,N-isopropyl acrylamide is used as the monomer,XLG type synthetic lithium magnesium silicate is used as the crosslinking agent,and nano-wood pulp cellulose is used as the reinforcing phase.A biomimetic double-layer temperature-sensitive smart hydrogel with both mechanical strength and deformation properties was prepared by the technique.Nano-wood pulp cellulose has good performance control ability for temperature-sensitive smart hydrogel.As the cellulose content of nano-wood pulp increases,the hydrogel crosslink density increases,the internal micro-pore diameter decreases,and the swelling ratio decreases.The higher the swelling ratio,the greater the breaking strength,the smaller the elongation at break,and the larger the tensile modulus.At the same time,the nano-wood pulp cellulose can be used to control the swelling property of temperaturesensitive smart hydrogel,and the anti-swelling anisotropy between the two-layer structure is the self-driven mechanism.Under the temperature stimulation,the bionic double-layer temperature sensitivity is realized.The type of smart hydrogel is effective for bending deformation.(4)By adjusting the ratio of temperature-sensitive smart hydrogel materials,the UV-curing molding method of 3D printing was realized,and the photoinitiator content of 35mg/mL and the irradiation time of 3min were selected as the optimal photocuring molding parameters.At the same time,the feasibility of temperature-sensitive smart hydrogel 3D printing is realized by using the nano-wood pulp cellulose to control the storage modulus,loss modulus and apparent viscosity of the temperature-sensitive smart hydrogel solution.NFC10-BASF-UV35 with a nano-wood pulp content of 10 mg/mL was selected as the best material system for the preparation of temperaturesensitive smart hydrogels by 3D printing.(5)Based on the biomimetic layered network structure model,a high-precision microstructure-structured temperature-sensitive intelligent hydrogel was prepared by 3D printing technology.By changing the arrangement angle,aspect ratio and fill rate parameters of the biomimetic layered network structure model,the effective control of the self-driving deformation of the bionic 3D print sample is realized.Among them,the "distribution angle" affects the final three-dimensional shape effect of the self-driven swelling deformation: 0°/90° structure can realize a semicircular groove shape curved along a short axis,and a 45°/135° structure can realize a spiral hollow cylinder,90 The °/0 structure can realize the semicircular groove shape curved along the long axis;the "horizontal to longitudinal ratio" affects the pitch of the spiral hollow cylinder: the larger the aspect ratio parameter,the smaller the pitch of the spiral hollow cylinder;the "filling rate" affects the spiral The pitch of the hollow cylinder and the swelling rate of the smart hydrogel: the smaller the filling rate,the smaller the pitch of the spiral hollow cylinder,and the faster the swelling rate of the hydrogel filament.(6)The bionic temperature-sensitive smart hydrogel prepared by 3D printing has reversible self-driven spiral deformation characteristics under temperature driving conditions,and the self-driving function of the biological model is realized efficiently,and the bionic function is realized efficiently.