Pulsed-plasma polymerization of 1-vinyl-2-pyrrolidone: Synthesis of a linear polymer

The RF plasma induced polymerization of 1-vinyl-2-pyrrolidone was examined under variable duty-cycle pulsed-plasma conditions. Large-scale progressive changes in the composition of the resultant polymeric films were observed with sequential changes in the plasma duty cycle employed during polymerization, all other plasma variables held constant. The film compositional changes obtained are in the direction of increased retention of the lactam ring of the monomer in the resultant polymers as the duty cycles employed (i.e., the ratio of plasma on to plasma off times) were decreased. Particularly significant are the relatively linear polymeric structures obtained under the exceptionally low-average power deposition conditions made accessible with the pulsed plasma technique. XPS and FTIR spectroscopic examination of these latter films reveal compositions that are similar to those obtained by conventional(i.e., nonplasma) synthesis of the linear polymer. The film chemistry controllability demonstrated in the present study is achieved while maintaining the many advantages of the plasma polymerization approach for surface modifications. This work provides additional support for use of the pulsed operational mode as an effective means of film chemistry control, in particular extending the plasma polymerization technique to include synthesis of linear polymers, in Lieu of the more highly crosslinked structures typically produced in conventional continuous-wave plasma polymerization processes. (C) 1998 John Wiley & Sons, Inc.