Synthesis And Characterization Of Carboxybetaine Functional Polysiloxanes For The Preparation Of Ultralow-fouling Surfaces

The nonspectific adsorption/adhesion of protein and bacteria onto the material surfacesare serious problems for biomedical and engineering applications. For example, theadsorption of protein on the surface of implant biomaterials would cause thrombus and evenlead to surgical failure, adhesion of bacterial onto biomaterial surfaces would lead to infectionand many other problems. And it was noticed that the effective adsorption of protein on thematerial surface is the fundament of the attachment, survival and reproduction ofphytophagous insects on plant surface, if this process could be regulated by changing themicroenvironment of plant surface, we may controlled the pests in a harmless way. And theemphasis of the process is how to create a non-fouling surface. Therefore, it’s a greatchallenge to prevent the nonspecific protein adsorption on surfaces in many areas (such asbiomedical devices, marine engineering, membrane separation technology, pest control, etc).In this thesis, a series of novel carboxybetaine functional polydimethylsiloxane (PDMS-g-CB)were synthesized via a three-step procedure, and we studied the solution properties andbiological properties of PDMS-g-CB. To evaluate the anti-fouling properties and hydrophilicproperties of PDMS-g-CB, PDMS-g-CB were embedded into polydimethylsiloxaneselastomer (PDMS) by blending. As another possible route, we prepared betaine modifiedPDMS by chemical grafting method, and the anti-fouling properties were investigated. Themain research work and results are described as follows:(1) A series of hydrogen-containing polysiloxanes (PDMS-co-PHMS) with a relativelynarrow molecular weight distribution were controlled synthesized via ring-opening polymeri-zation of octamethylcyclotetrasiloxane (D4) and1,3,5,7-tetramethylcyclotetrasiloxane (DH4).Then PDMS-g-CB were synthsized via hydrosilylation reaction and quaternization reaction.The chemical structures of products were confirmed by FT-IR and1H-NMR, and the optimumreaction conditions for the preparation of PDMS-g-CB were determined by orthogonal tests.(2) Analysis of the PDMS-g-CB aqueous solution showed that PDMS-g-CB have sometypical characteristics of zwitterionic polymers: they are water-soluble, having a strong ability to form micelles (CMC <0.1g/L), exhibiting the unique isoelectric point characteristic ofzwitterionic polymers at pH=6. Besides, PDMS-g-CB have good film forming ability, theycan form a hydrophilic film on glass slide surface. And they also have good biocompatibility(no skin irritation, non-toxic, no bacteriostatic/bactericidal effect)(3) PDMS-g-CB were embedded into polydimethylsiloxanes elastomer by blending(b-PDMS), the hydrophilic properties and anti-fouling properties (anti-protein adsorption,anti-bacterial adhesion) of PDMS were improved significantly by introducing PDMS-g-CB,and the b-PDMS still have a good blood compatibility.(4) Carboxybetaine was grafted to PDMS surface by hydrosilylation reaction, themodified surface (g-PDMS) shows good hydrophilicity, it can dramatically reduce theadsorption/adhesion of protein and bacteria.