| The DBD plasma polymerization working at atmospheric pressure has been widely concerned in the field of material surface modification. One of its most attractive features is that it does not damage the inherent nature of materials with wide monomers and no solvents. In this thesis, an atmospheric pressure plasma jet(APPJ) system which had a highly conductive liquid-electrode was designed, and its preliminary discharge and polymerization characteristics pushed by the DC pulsed and AC power. Meanwhile, the different characteristics of Ar and He pulsed APPJs polymerization occurred in the PVC tube with AA monomer were investigated, as well as the polymerizing characteristics of AC plasma jet. Moreover, the surface modification of PMMA films by AC plasma polymerization was also explored to improve its hydrophilicity and biocompatibility.It was found that the Ar and He pulsed plasma jets could propagate well in the PVC tube, and their propagation distance in the PVC tube increased obviously with increasing the working gases flow rate. The discharge current of the He and Ar pulsed plasmas increased with applied voltage increasing, and their discharge voltage- current characteristic curves were similar under the same applied voltage. Moreover, in the light of the OES results, there were many reactive species existed in both Ar and He pulsed plasma jets, such as OH and O, which had a significant impact on the plasma polymerization.The remarkable feature of fabricated acrylic acid polymer(PAA) by APPJ s is that PAA films are composed of many nanocones, and the size and density of nanocones influenced by many factors such as discharge gas types, the flow rate of gases, the heated temperature of AA monomer, and the discharge model. The average heights of PAA nanocones deposited by He and Ar pulsed plasma jets were similar under the same condition, which were about 65.84 nm and 66.78 nm, respectively. Moreover, the nanocones density deposited with He pulsed plasma jet was higher, but its uniformity was relatively lower. The hydrophilicity of the inner surface of modified PVC tube increased greatly, and its contact angle increases approximately linear with the plasma intensity propagated in PVC tube. The XPS results indicated that the ratio of COOH/R on the inner surface of modified PVC tube by He plasma jet was higher than that modified with Ar plasma jet, and the ratios of COOH/R were about 6.81% and 4.97%, respectively. The cell adhesion experiment presented that the cells attached on the inner surface of plasma-modified PVC tube showed a ellipse or fusiform profile, and the cells number attached on the inner surface of PVC tube modified by He pulsed plasma jet was about 1×105/mm2 higher than that modified with Ar pulsed plasma jet. In addition, when the AC power supply was used to modify the PVC tube, the density and uniformity of deposited PAA nanocones increased obviously. However, the average height of nanocones was relatively lower, and it was about 14.28 nm. The XPS results revealed that the COOH/R ratio on the inner surface of treated PVC tube by AC plasma jet was about 3.44%, which was lower than that treated by pulsed plasma jet.According to FTIR and XPS results, the concentration of polar group on the surface of PMMA films increased after being modified by AC plasma polymerization, and it increased with the applied power increasing. The ratio of COOH/R on the treated PMMA film with an applied power of 50 W was about two times higher than that of 30 W. CA result revealed that the water contact angle of PMMA film decreased signally after AC plasma modification. The contact angle value of untreated PMMA film was about 100°, and it was smaller than 50° when the applied power was 50 W. The cell adhesion experiment results revealed that the number of attached cells on the PMMA film increased obviously with increased the discharge power. It should be noted that the polymerization modification not only improved the adhesion of the original PMMA film, but also improved its biocompatibility. |
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