The Preparation And Characterization Of Nanocomposite Polyelectrolyte Hydrogels

Hydrogels have been widely applied in biomedicine,tissue engineering,artificial muscle,chemical sensor and so on.We have successfully prepared physical hydrogels crosslinked by electrostatic attraction through CO₂-induction and AgNO₃-induction.The preparation methods are environmentally-friendly and original,providing a new way to prepare hydrogels.The research results are as following:?1?In this thesis,we compounded poly?sodium 4-styrenesulfonate??PSS?and poly?dimethylamino-propyl-methacrylamide??PDMAPMA?,then blew CO₂ to the surface.PDMAPMA got positively charged after being protonated,the protonated PDMAPMA crosslinked with negatively charged PSS by electrostatic interaction.At the same time,different solid content of negatively charged CNC with-SO₃-were added into the system.CNC could interact with protonated PDMAPMA by electrostatic attraction and hydrogen bonds,leading to the increase of crosslinking density and moduli of the hydrogels.In order to explore the properties of the hydrogels,we have conducted tests such as scanning electron microscopy?SEM?,fourier transform infrared spectroscopy?FTIR?,swelling behavior,rheological property,biocompatibility and moldability.It can be easily found there were micro-nano scale pores and CNC/polymer clusters distributing uniformly in the composite.When CNC loading increased from 0 to 5%,the pore size was getting smaller,the reason was that there were more CNC/polymer clusters and attraction in the system with the increase of CNC.FTIR spectrum depicted that the peaks of C-N in amino groups shifted from 1180 cm-1 to 1174 cm-1,demonstrating that most of the amino groups were protonated by getting H+.The equilibrium swelling ratio of hydrogels decreased when the solid content of CNC increased,it indicated that CNC was contributed to build more compact physical crosslinking system.In the process of rheology frequency sweep tests,we found that storage modulus?G??and loss modulus?G??of hydrogels went up sharply as CNC loading increased.Furthermore,CCK-8 assay showed that polyelectrolyte hydrogels had good biocompatibility to confluent osteoblasts?SD rat?cells.Hydrogels loaded with CNC supported better proliferation of osteoblasts than neat hydrogels,the difference was likely associated with the favorable biocompability of CNC.Therefore,many potential biomedical applications could be envisioned.Meanwhile,this system possesses fabulous moldability,which means we can prepare some free-standing hydrogels with different shapes.?2?Polyelectrolyte precursor can also be transformed into polyelectrolyte hydrogel with AgNO₃-induction.This might be associated with the redox reaction between PDMAPMA and Ag+: PDMAPMA could be oxidized into quaternary ammonium salt by Ag+,Ag+ was reduced into silver.Protonated PDMAPMA can then integrate with negatively charged PSS by electrostatic interaction.When the AgNO₃ solution concentration increased,it accelerated the membrane forming speed.The anti-bacteria test demonstrated that AgNO₃-induced film has excellent antibacterial property.