The interaction of hydrogen and ammonia plasmas with polymethacrylic esters, studied by static secondary ions mass spectrometry

The interactions of H2 and NH3 plasmas with the surfaces of various poly(alkylmethacrylate)s and of poly(phenylmethacrylate) have been studied with XPS and SSIMS. Experiments on poly(methylmethacrylate) reveal that during short treatment times with the NH3 plasma chain, scission takes place and nitrogen is not incorporated into the surface. The chain scission also takes place with the H2 plasma. With the aid of SSIMS results, the nature of the chain scission could be deduced. Comparison of these results with those on poly(n-butylmethacrylate) and poly(t-butylmethacrylate) reveals a reaction mechanism in which hydrogen atoms generated in both plasmas play an important role in the chain scission process. After longer treatment time with the NH3 plasma, the poly(methylmethacrylate) surface becomes deoxygenated and nitrogen is incorporated into surface structures of low molecular weight. Experiments on poly(phenylmethacrylate) reveal that already during short treatment times with the NH3 plasma, nitrogen is incorporated into the aromatic ring. Chain scission does not play an important role. One of the processes with the H2 plasma is hydrogenation of the aromatic ring, leading to poly(cyclohexylmethacrylate).