Synthesis And Performance Study Of Composite Hydrogels

This thesis focuses on the preparation of hydrogels with good strength and toughness by a simple method,and correlates the hydrogel structure,properties and applications by systematically determining the mechanical properties,swelling behavior and structure of hydrogels.The first chapter is a literature review,the second and third chapters are the study,and the last chapter is the conclusion.（1）.Three organically cross-linked hydrogels were prepared using free radical copolymerization of 2-acrylamido-2-methylpropanesulfonic acid（AMPS）,acrylic acid（AA）,acrylamide（AM）,and N,N-diethylacrylamide（DEAA）as monomers:poly（AMPS-co-AA）hydrogel,poly（AMPS-co-AA-co-AM）hydrogel,poly（AMPS-co-AA-co-DEAA）hydrogels.How the hydrogel composition（2-acrylamido-2-methylpropanesulfonic acid,acrylic acid,acrylamide,N,N-diethylacrylamide）contributes to the mechanical properties of the hydrogels was examined,the effects of composition and environmental factors（p H and salt concentration）on the swelling behavior were determined,and the structure of the hydrogels was explored.The elongation at break of the hydrogels was only 43% when only two monomers,AMPS and AA,were present in the polymer chains.The addition of AM and DEAA,respectively,can regulate and optimize the mechanical properties of the hydrogels（58% elongation at break and 0.02 MPa tensile strength after the addition of AM;160% elongation at break and 0.06 MPa tensile strength after the addition of DEAA）.Meanwhile,the hydrogel can swell highly and deeply in water with unique swelling behavior and responsiveness to PH and salt concentration.（2）.Because of the special structural composition of montmorillonite（MMT）,which allows montmorillonite to increase the physical cross-linking point of hydrogels by adsorbing macromolecular chains and thus enhance the mechanical properties of the composites,drawing on one of the properties,10 samples were first prepared to investigate the effect of the variation of the content of each monomer on the mechanical properties of the hydrogels.The results showed that the tensile strength and elongation at break of the hydrogels were significantly improved（maximum tensile strength of 0.2 MPa and elongation at break of 1800%）while maintaining the simple preparation method,high stretchability and unique swelling behavior.In addition,five samples were prepared to investigate the effect of the variation of montmorillonite content on the mechanical properties of the hydrogels,and the results showed that the tensile strength tended to increase and the elongation at break tended to decrease with increasing montmorillonite content.It is assumed that the interaction between montmorillonite and polymer,such as hydrogen bonding,acts as a stress transfer,which makes the hydrogel more rigid and has the property of resisting crack growth.The main significance of this thesis is the use of a simple method to prepare a class of hydrogels with excellent mechanical properties,which have promising applications in drug delivery and release,smart materials（microvalves）,etc.