Applications Of Low Temperature Plasma In Surface Modification And Initiated Polymerization Of Polymers

As an environmentally friendly, high efficiency technology, low temperatureplasma has attached lots of researchers’ interests and attentions and has been appliedin surface modification, surface initiated polymerization and initiated polymerizationdue to its advantages, such as no affect on mechanical properties and solvent avoid.In this dissertation, N₂+H₂, Ar+O₂, NH₃+O₂gas mixtures plasma were appliedunder vacuum conditions to modify the surface of PCL eletrospun membranes and theplasma treatment effects on cell proliferation and morphology were also determined.HA fibers and additives were used to improve the mechanical properties of PCLmembrane. Normal plasma at atmorsphere was used to graft GMA on the surface ofPTFE plates and plasma flames at atmosphere pressure were used to modify PCLmembrane’s surface. DBD was used to initiate the styrene-maleic anhydridecopolymerization, copolymers’ chemical structure and effects of solvents were alsodetermined.From the results, nitrogen-containing and oxygen-containing functional groupscould be grafted on the surface of PCL membranes. The hydrophilic properties couldincrease with prolonging the treatment time. Cell culture data indicated that PCLmembranes after each plasma treatment had the nearly same bioactive properties anddifferent degrees of surface wetablitiy had effects on the cell proliferation. Twodimensional aligned membranes were obtained and proved that the aligned nanofiberscould guide cell growth direction and adjust the cell morphology.The results showed that HA fibers had no effect on the PCL mechanicalproperties due to their incompatible interface. Plasma etching, surface graftpolymerization and additives were applied to improve the interface compatibility,only the additive could improve the ultimate tensile stress3times of that of the purePCL, due to that the addition of additive could induce the increase of crystallinitydegree and molecular chain orientation.After plasma treatment, the surface roughness increased and O-containing groupscould be grafted on the surface of PTFE. GMA could be grafted on the plasmamodified surface of PTFE and formed aligned stripes. The thermal treatment provedthat the stretch induced aligned GMA stripes on PTFE surface. Dc plasma treatment at atmosphere temperature had slightly effect on the surface of PCL, due to the lowenergy of electron and high temperature of plasma flame.The copolymerization could be initiated by DBD at atmosphere temperature. Thatthe chemical structure of copolymer had dominant alternating structure with ratherlittle randomness. Prolonging the post-polymerization time could increase the yieldand molecular weight when using acetone as the solvent, but had little effect on thosewhen using xylene as the solvent.