| Janus spherical particles are widely used in solid surfactants,polymer interface compatibilization,biomedicine and other fields due to their special chemical composition.Janus nanosheets have higher interface energy than Janus spherical particles.In this paper,Janus nanosheets were synthesized by sol-gel method,and the toughening and strengthening effect of Janus nanosheets on epoxy resin(EP)and hydrogels were studied.The preparation and application of Janus smart hydrogels were also studied.The main research contents and results are as follows:1.Two types of Janus nanosheets were synthesized by sol-gel method,namely nanosheets with amino on one side and double bonds on the other side(JNS1)and nanosheets with amino on one side and epoxy on the other side(JNS2);And EP/JNS1 and EP/JNS2 epoxy composites were prepared by in-situ polymerization.Janus nanosheets have toughening and strengthening effects on EP at the same time.It is sterically hindered by rigid sheet-like JNS1,which is suspended on the EP main chain;but JNS2 and EP matrix together form a three-dimensional framework network structure,so JNS2 has better toughening and enhancing effect.When the content of JNS2 is 0.5%,EP/JNS2 has the best impact effect,which is 33.19 k J/m~2,which is 57.08%higher than that of pure EP;In addition,since Janus nanosheets can block heat transfer,the thermal stability of the two composite materials has also been improved.2.Janus hydrogel whose water phase is poly dopamine-poly acrylic acid(PDA-PAA)and the organic phase is poly butyl methacrylate-poly isooctyl methacrylate(PBMA-PEHMA)was successfully prepared by one-step polymerization of incompatible monomers.The adhesion effect of DA makes the water phase gel have good adhesion performance;DA and AA,the chemical bond and hydrogen bond between each other,and the?-?stacking of DA make the water phase gel have good self-healing performance.When Janus hydrogel is placed in aqueous solution and organic solvent respectively,the internal stress difference caused by swelling make the gel bend in different directions in different media.In addition,after adding sodium chloride to the water phase,due to the ionic conductivity of sodium chloride in the water phase,Janus hydrogel has good electrical conductivity.It can monitor the hydrophilic and hydrophobic properties of the solution system by observing the changes in its current signal variety.Conductive Janus gel can also be used to monitor large movement and micro movement of human body,the result of this anisotropy is a conductive material with its own insulation,which can reduce the impact of harsh environments on monitoring,so it has certain application prospects in flexible sensing.3.Different contents of JNS1 were added to PAA hydrogels by in-situ polymerization,JNS1 as rigid flake particles could prevent cracks from expanding further under external force.When the amount of JNS1 is 0.03 g and the ratio of water to glycerol is 1:1,the tensile strength of PAA hydrogel is 58.75 k Pa,the elongation at break is 305.76%,and the compressive strength is 284.64 k Pa,which is 55.42%,59.72%and 69.88%higher than that of hydrogel without JNS1.Due to the antifreeze property of glycerol at low temperature,the hydrogel has good anti freezing ability with the increase of glycerol content in PAA hydrogel.Janus nanosheets as rigid fillers,coupled with their surface groups,can form a three-dimensional network skeleton structure with polymer matrix(epoxy resin,hydrogel),and play a good toughening and strengthening effect on matrix.At the same time,anisotropic Janus smart hydrogel provides a new research idea for the preparation of new materials. |
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