(28a) Photo-Enhanced Atmospheric Plasma-Assisted Chemical Vapor Deposition: UV-Plasma Synergies Under Ambient Conditions

Plasma-assisted chemical vapor deposition (PA-CVD) has been used extensively since the 1980’s to deposit polymer films on substrates for applications ranging from semiconductor manufacturing to textile treatment to membrane and biomedical device processing.  PA-CVD techniques are advantageous for producing ultrathin, highly-crosslinked, pinhole-free films on complex surfaces, often from starting monomers that lack the chemistry for traditional polymerization techniques, without a need for solvents or standard chemical initiators.  Polymers with different material properties—e.g. surface energy, degree of crosslinking—can be produced from a single monomer by varying the geometry, electrical characteristics, and energy density (i.e. Yasuda parameter) of the plasma discharge.  The polymer surface can then be decorated with a desired chemical functionality by polymerizing an appropriate monomer or by treatment with an appropriate plasma species, e.g. amination with allylamine or an ammonia plasma.  Functionalization can provide a handle for further chemistry, enabling nanoparticles (antimicrobial surfaces), small molecules (microanalytical chemistry), or even biomacromolecules (tissue engineering) to be conjugated to the surface.

Recent work has sought to adapt plasma-assisted CVD and functionalization to ambient conditions with atmospheric non-thermal plasma discharge systems, for the in situ treatment of surfaces that are not amenable to processing under typical vacuum chamber CVD conditions.  Many such processes have been developed, but atmospheric pressure conditions constrain the set of precursors and discharge conditions, somewhat limiting the range of achievable film properties.

In collaboration with Dr. J. Gary Eden (U. Illinois), I am evaluating the use of high-emittance photon sources—UV-A and UV-B light-emitting diodes, UV-B and UV-C microcavity plasma discharges—for enhancing plasma-assisted CVD at atmospheric pressures.  I present data that suggests that photoionization of gaseous and precursor species can be utilized to extend the operating range in a dielectric barrier plasma jet by improving plasma stability and aiding in precursor fragmentation.