| Biomaterials,especially polymers,metals and ceramics are a necessity in our everyday lives due to their major contribution to the development of a completely new approach in disease curing.Trauma or congenital defects cause physiological system dysfunctions or loss of body parts,which often require surgical repair.This mostly necessitates replacement of the skeletal parts that include hips,knees,finger joints,vertebrae,elbows,teeth,and other vital organs such as heart,kidney and skin,etc.Biomaterials are used as replacements,to perform the respective functions of the living materials.Polymers are the most convenient materials for biomedical applications including cardiovascular devices for the proliferation and replacement of numerous soft tissues.Silicone polymers have extensively been used as biomaterials due to their good biocompatibility,good oxygen permeability,good mechanical properties,thermal stability,optical transmittance,durability,UV resistance and low cost.However,polydimethylsiloxanes are naturally hydrophobic,this leads to the historical problems such as increased lipid interaction,decreased surface wettability as well as accentuated lens-binding,hence the need for continuous refining of PDMS materials.Polyurethane materials are used extensively due to their excellent properties such as excellent chemical resistance,oil resistance,abrasion resistance,good shock absorption effect,tensile strength and high elongation.Therefore,developing methods for combining polysiloxanes and polyurethanes to prepare a polysiloxane-polyurethane copolymer material that combines their excellent properties and modifying their surface from hydrophobic to hydrophilic would bring us a novel class of biomaterials.In this thesis,simple,nature friendly(solvent-free)and cost effective methods for fabricating a biomaterial based polysiloxane-polyurethane,hydrophilic surface modifications and responsive hydrogel were developed and optimized,followed by characterization of the prepared materials.The experimental details of are as follows;In the first research,an intermediate macromonomer PDMS-IPDI was prepared by the condensation reaction between carbinol(hydroxyl)terminated polydimethylsiloxane and a crosslinker isophorone diisocyanate.2-hydroxyethyl methacrylate(HEMA)was incorporated into the intermediate to obtain PDMS-HEMA macromonomer.The(PDMS-HEMA)polysiloxanepolyurethane film was prepared via ultraviolet radical polymerization.The whole process did not utilize any solvent or additive.Infrared spectroscopy was employed to verify the formation of PDMS-HEMA film.The as-prepared PDMS-HEMA films were thereafter,hydrophilized via physical treatment with heptamethyltrisiloxane.The surface properties of the obtained PDMSHEMA films were characterized in terms of wettability,morphology,topography,swelling,mechanical properties and protein adsorption.Compared to pristine PDMS-HEMA as control,the surface wettability,roughness and protein adsorption of the hydrophilized PDMS-HEMA films were significantly improved while the films also exhibited excellent optical properties.However,the improvement of the swelling properties remains insignificant,indicating that the interior morphology was still based on the hydrophobic siloxane PDMS.The long-term hydrophilicity was considered good,as no significant hydrophobic recovery was noticeable in a period of five months after treatment.In the second research,silicone hydrogels were fabricated by combining previously prepared hydrophobic(PDMS-HEMA)with typical hydrophilic polymer poly(ethylene glycol)methacrylate(PEGMA)via radical polymerization reaction without using any solvent or additive to obtain PDMS-HEMA-PEGMA film.The Infrared spectroscopy results confirmed the PDMSHEMA-PEGMA network formation,while the hydrophilicity of the as-prepared block copolymer was dependent on(PDMS-HEMA)/PEGMA ratio.Increasing the PEGMA content resulted in increased equilibrium water content(EWC),phase separation,surface roughness and tensile strength,while the elongation at break,optical transmittance and decreased water contact angle(WCA)and protein adsorption.The TGA results also revealed that the PEGMA content had no obvious effect on thermal stability of hydrogels.In the third research,a series of silicone hydrogels,which displayed multiple response towards pH and solvent stimuli were prepared via radical copolymerization of the hydrophobic macromonomer PDMS-IPDI and the hydrophilic reaction mixture(HEMA-NVP-DMA).A series of multifunctional responsive hydrogels were prepared and visual inspection method was used to observe their responsive capabilities based on their swelling lengths.The hydrogels were able to estimate the pH of the solutions,distinguish different solvents and detected the content of organic solvent in water.Interestingly the hydrogels were reusable. |
