Preparation Of PBA Microspheres Toughening Physical Crosslinking Dual-network Hydrogels

Hydrogels are a kind of wet and soft materials with high water absorption performance,and can't be dissolved in the water.This material is consisted of a large amount of water and the hydrophilic three-dimensional polymer network,its structure is very similar with biological tissue,therefore,hydrogels in biomedical,conduction release,medical equipment,tissue engineering and other fields have a wide range of applications.However,these applications usually rely on the strong mechanical properties of hydrogels,and the weak performance of them severely affects their application.Although people have paid more attention on relevant research,there are still many problems to be solved,such as the recoverability.Dual-network hydrogels(DN hydrogels)are a class of hydrogels synthesized by combining two different chemicalnetworks.It has excellent mechanical properties,such as strength and toughness.However,the traditional dual-network hydrogel has a lot of restrictions: First,as the sacrifice of the first network can not be restored after the destruction;Second,the synthesis process is complicated,and difficult to control.These issues need to be addressed further.In this paper,we use gelatin as a first network of hydrogels with sol-gel transition properties,and it can not only provide energy loss for hydrogel loading,but also possess the recoverability of the physical network structure.At the same time,the hydrophobic association network with PBA latex microspheres(MMs)as the hydrophobic association centers acts as the second network of hydrogel,which can effectively improve the toughness of DN hydrogel.Based on this model,the DN hydrogel completely composed of physical networks was prepared,and the experimental results shown the following situations: Firstly,the introduction of gelatin effectively changed hydrogel's network type,and spiral physical crosslinking gelatin network as “sacrificial bonds” effectively improve the energy loss of hydrogel under the load thereby increasing the toughness of hydrogel.Secondly,the introduction of hydrophobic emulsion microspheres could enhance the toughness of the hydrogel.The hydrophobic association interaction with hydrophobic microspheres as centers could separate and restructure under the action of external force,and this process made the interior network distribution of hydrogel more uniform and dissipated greatly energy thereby endowing the hydrogel with excellent mechanical properties.Thirdly,the content,particle size of emulsion microspheres,the content of hydrophobic monomer,and the content of gelatin had influence on the hydrogel performances.When the content of gelatin was 10mg/mL and the contents of emulsionmicrospheres(422.3 nm)and hydrophobic monomers were 1.0wt% and 0.3mol% for AAm monomer,the hydrogel possessed excellent mechanical properties,including the elongation of 2100%,the fracture strength of 1.49 MPa and the fracture energy of 8.83MJ/cm3.Finally,the machinal strength and loss of hydrogel hardly changed and the hydrogel had strong recoverability under the cyclic tensile loading test(by 500%)and the cyclic compression test(90% compression deformation).The hydrogel is put forward as a novel strategy for the study of the hydrogel toughening ways,and it is expected to be as strong human tissue materials for applications in the future.