The Investigation Of Polymer Surface Modification By Cold Plasma Induced Grafting Polymerization

This paper studied the surface modification of polymer by plasma-induced polymerization method.Firstly,it was confirmed that acrylonitrile or acrylamide was grafted onto the polymer surface by ATR-FTIR analysis when using polyethylene as substrate.The influence of grafting reaction condition to the grafting ratio was also investigated.The higher the reaction temperature was,the higher the grafting ratio was.The grafting ratio increased sharply when the reaction temperature reached boiling temperature of the reaction solution.The grafting ratio was proportion increasing with the monomer concentration.The grafting degree increases along with the prolonging of reaction time. The solvent had great influence to the grafting reaction.The grafting ratio was zero when only using methanol as the solvent for acrylonitrile or acrylamide.The grafting ratio was not zero when only using ethanol or isopropanol as the solvent for acrylonitrile or acrylamide.The grafting ratio increased with the increasing of volume ratio R(R=V_H2O/V_CnH2n+1OH) when using methanol and water as mixed solvent for PE grafting with acrylonitrile.If R is zero,that is to say,only using ethanol or isopropanol as the solvent,the grafting ratio has maximum values for PE grafting acrylonitrile by using ethanol and water or isopropanol and water as mixed solvent.The grafting ratio decreases when the solvent contains water.For PE grafting with acrylamide,the grafting ratio has the following changing trend at the same volume ratio R by using mixed solvent.(isopropanol + water)≥(ethanol + water)＞(methanol + water)The grafting ratio has maximum value when R is zero by using isopropanol and water as mixed solvent for PE grafting with acrylamide.Secondly,this paper also studied the surface modification of PET by grafting with methacrylic acid or acrylic acid through plasma-induced polymerization method.The factors to influence the grafting reaction were investigated in detail.The higher the reaction temperature is,the higher the grafting ratio is.The grafting ratio increases sharply when the reaction temperature reaches the boiling temperature of the reaction solution.The grafting ratio is in proportion to the increasing of monomer concentration. The grafting ratio increases along with the prolonging of reaction time.The grafting ratio of PET grafting with methacrylic acid is greater than that of PET grafting with acrylic acid at the same reaction condition.The solvent has great influence to the grafting reaction.The grafting ratio increases with the increasing of volume ratio R, which is defined by the volume of water to the volume of alcohol,when using alcohol and water as mixed solvent.The grafting ratio is not zero when only using methanol, ethanol or isopropanol as the solvent.The grafting ratio has different changing trend for PET grafting with methacrylic acid or acrylic acid at the same volume ratio by using mixed solvent.PET-g-AA:(ethanol + water)＞(methanol + water)(ethanol + water)＞(isopropanol + water)PET-g-MAA:(ethanol + water)≥(isopropanol + water)≥(methanol + water)The red shift in UV spectrum could be ascribed to different reactive activities of acrylic acid or methacrylic acid in different solvents,which also can explain the change trend of the grafting ratio.The UV-vis absorbance difference and the FTIR integrated peak area of the C=O stretching increase steadily with the increase of grafting ratio, which are almost linear relationship.It was confirmed that acrylic acid and methacrylic acid were grafted onto the PET surface in terms of UV-vis spectrophotometric,FTIR and AFM analysis.