Study On The Bionic Structure Design And Preparation Of Magnetic Response Intel Igent Hydrogel

Intelligent hydrogel is a kind of polymer material with continuous three-dimensional network structure which can be fully expanded in water without dissolving,that hava many superior characteristic such as high water absorption,high water retention,good biocompatibility,fast response and high mechanical strength.It can be used as medical treatment,biological engineering,electronics,artificial muscles,etc.The magnetic response intelligent hydrogels have the advantages of non-contact response,convenient driving,high efficiency,no capacity loss and harmless to biological tissue.It is widely used in medicine carrier,cell engineering,flexible actuator and other fields.With the expansion of the application range of magnetic response intelligent hydrogels,taking into account both mechanical strength and multi-form intelligent response has become a bottleneck problem.Under the premise of good mechanical strength,many plants in nature have highly efficient self-driven deformation function.It provides a significant biomimetic inspiration for solving the bottleneck problem of magnetic response intelligent hydrogels.The hygroscopic awn of hydrangea seed realized self-driven seeding function by twisting spiral deformation and untwisting spiral deformation under the condition of humidity.This paper takes the hygroscopic awn of hydrangea seed as the biological model.A bionic bilayer structure model with anisotropic swelling degree is established based on the microstructure characteristics of the deformed part and the self-driven deformation mechanism that guided the design and preparation of bionic magnetic response intelligent hydrogels.Taking N,N-Dimethylacrylamide?DMAA?as monomer,XLG type synthetic magnesium lithium silicate as cosslinking agent,nano wood pulp cellulose as reinforced phase,Fe₃O₄ as magnetic response particle,prepared PolyN,N-Dimethylacrylamide?PDMAA?by physical crosslinking method.And we prepared the bionic bilayer intelligent hydrogels with the characteristics of swelling and self-driven by magnetic response successfully through the"one-step method"molding technology.It realized the effective balance between mechanical strength and multi form intelligent response and provided an effective new idea and method for solving the bottleneck problem of intelligent hydrogels.The specific research content and main conclusions are as follows:?1?The hygroscopic awn of hydrangea seed is very sensitive to the humidity of air that has self-driving deformation function under humidity condition.It consists of awn base,awn spiral and awn tail.The main function of the bending rotation of the hygroscopic awn is the awn spiral part which is composed of the spiral inner layer and the spiral outer layer.?2?The self-driven deformation mechanism of the hygroscopic awn is as follows:in dry condition,the content of cellulose in spiral inner layer is low,the cell loses water,wall becomes thinner,radius becomes smaller;the content of cellulose in spiral outer layer is low,The length of the fiber will not shorten and the overall size of the spiral outer layer is basically the same with the decrease of air humidity.In humid condition,the inner cells absorb water,the radius increases,and the overall size of the inner tissues increases.The inner tissue drives the outer tissue to start stretching and getting longer.The outer layer mainly plays a guiding and regulating role.?3?Established the bionic bilayer structure model based on the microstructural properties of the hygroscopic awn of hydrangea seed.The model is divided into two layers,and there is anisotropy in the degree of swelling between each layer.This model can realize the self-driving function similar to the biological model through the difference of swelling degree between the two layers.?4?Prepared PDMAA intelligent hydrogel material system by In situ free radical polymerization combined with die forming technology based on the bionic bilayer structure model from the hygroscopic awn of hydrangea seed and analyzed the structural properties,material properties and mechanical properties.Taking nano wood pulp cellulose as reinforced phase,prepared NFC-PDMAA hydrogels with controllable swelling.The increase of NFC content increased mechanical strength of nfc-pdmaa hydrogel,and effectively regulated its swelling property.Taking Fe₃O₄ as magnetic response particle,prepared Fe₃O₄-PDMAA hydrogels with magnetic responsiveness.Increasing the content of Fe₃O₄ did not improve the crosslinking density of the Fe₃O₄-PDMAA hydrogel.Fe₃O₄ reduces it's mechanical properties but realizes the magnetic response of intelligent hydrogels.The magnetic response of Fe₃O₄-pdmaa hydrogel can be effectively changed by regulating the content of Fe₃O₄.NFC-Fe₃O₄-PDMAA Hydrogels with high mechanical strength,controllable swelling and good magnetic response were prepared based on the optimal nano wood pulp cellulose and ferric oxide content.?5?Taking PDMAA?NFC-PDMAA?NFC-Fe₃O₄-PDMAA as materials,prepared NFC-PDMAA—PDMAA and NFC-Fe₃O₄-PDMAA—PDMAA bionic bilayer intelligent hydrogels successfully through the"one-step method"molding technology based on the bionic bilayer structure model from the hygroscopic awn of hydrangea seed.The upper layer of bionic bilayer intelligent hydrogels has larger pore size,lower crosslinking density and higher swelling performance.The lower layer has smaller pore size,higher crosslinking density and lower swelling performance.There is good bonding strength between layers.Due to the difference of swelling characteristics between the bionic bilayer intelligent hydrogels,it has the function of swelling and bending deformation in the water environment,and the deformation degree increases with the increase of cellulose content in the lower layer.Bionic biayer intelligent hydrogels have high magnetic response and high mechanical properties.It can grab objects up to 10 times their own weight.Good soft characteristics make it has a good grasp adaptability.