Paper SE+NS-MoA6
Creation of Highly Functionalized Polymer-Metal Oxide Nanomaterials Using A Novel Rotating Drum Plasma Reactor

Monday, October 29, 2012, 3:40 pm, Room 22

The use of nanoparticles in biological applications has grown rapidly in recent years. Understanding the surface chemistry and protein-nanoparticle interactions is critical in the fabrication of biomedical devices. Some nanoparticle surfaces are not compatible with specific applications, and thus must be modified to make them viable. Plasma processing of nanomaterials is an effective method for functionalization and encapsulation of nanoparticles. Our lab has designed a rotating drum inductively coupled plasma reactor that has afforded the ability to create specifically tailored nanoparticle surfaces. The rotating drum apparatus was utilized to encapsulate Fe₂O₃ and Au nanoparticles with various polymer films. Allyl alcohol, allylamine, and acrylic acid plasmas were used to incorporate alcohol, amine, and carboxylic acid functionality to nanoparticle surfaces, respectively. Tailoring of film composition was achieved by lowering the duty cycle (d.c.) of the plasma to facilitate less fragmentation of the monomer. This resulted in the deposited films being more stoichiometrically similar to the parent monomer gas and thus having a high concentration of functional groups present within the film. For example, the alcohol functionality of plasma polymerized allyl alcohol films on Fe₂O₃ nanoparticles can be substantially increased by lowering the d.c. of the plasma from 100 % to 10 %. Specifically, x-ray photoelectron spectroscopy elemental analysis shows that films deposited under low d.c. conditions increase O/C ratios from 0.17 to 0.35, which is comparable to that of the parent monomer (0.33). FTIR data reveal complementary results, where increases in OH functionalities are observed for low d.c. plasmas. Electron microscopy confirms there is no appreciable change in size and shape of the nanoparticles upon plasma treatment. The solubility and stability of the encapsulating films were analyzed to measure the longevity of the particles in biological systems. Highly functionalized films were also deposited onto supported nanoparticle substrates to investigate how plasma processing affects surface roughness, as this can affect cell adhesion. We have demonstrated that plasma processing can change the RMS roughness of supported nanoparticles by 0.2 μm, thereby affording the ability to tailor the roughness of a surface for specific cell interactions. A variety of gas-phase and surface analysis data will be presented to show how plasma processing can tailor the composition of deposited films of as a function of plasma parameters and gas-phase species. Understanding how these films are produced will undoubtedly advance the fabrication of novel biomedical devices.