3 research outputs found
Defining Plasma Polymerization: New Insight Into What We Should Be Measuring
External parameters (RF power and
precursor flow rate) are typically quoted to define plasma polymerization
experiments. Utilizing a parallel-plate electrode reactor with variable
geometry, it is shown that these parameters cannot be transferred
to reactors with different geometries in order to reproduce plasma
polymer films using four precursors. Measurements of ion flux and
power coupling efficiency confirm that intrinsic plasma properties
vary greatly with reactor geometry at constant applied RF power. It
is further demonstrated that controlling intrinsic parameters, in
this case the ion flux, offers a more widely applicable method of
defining plasma polymerization processes, particularly for saturated
and allylic precursors
On the Effect of Monomer Chemistry on Growth Mechanisms of Nonfouling PEG-like Plasma Polymers
It has been shown that both ions and neutral species
may contribute
to plasma polymer growth. However, the relative contribution from
these mechanisms remains unclear. We present data elucidating the
importance of considering monomer structure with respect to which
the growth mechanism dominates for nonfouling PEG-like plasma polymers.
The deposition rate for saturated monomers is directly linked with
ion flux to the substrate. For unsaturated monomers, the neutral flux
also plays a role, particularly at low power. Increased fragmentation
of the monomer at high power reduces the ability of unsaturated monomers
to grow via neutral grafting. Chemical characterization by X-ray photoelectron
spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry
(ToF-SIMS) confirm the role that plasma phase fragmentation plays
in determining the deposition rate and surface chemistry of the deposited
film. The simple experimental method used here may also be used to
determine which mechanisms dominate plasma deposition for other monomers.
This knowledge may enable significant improvement in future reactor
design and process control
Haptotatic Plasma Polymerized Surfaces for Rapid Tissue Regeneration and Wound Healing
Skin
has a remarkable capacity for regeneration; however, with an ever
aging population, there is a growing burden to the healthcare system
from chronic wounds. Novel therapies are required to address the problems
associated with nonhealing chronic wounds. Novel wound dressings that
can encourage increased reepithelialization could help to reduce the
burden of chronic wounds. A suite of chemically defined surfaces have
been produced using plasma polymerization, and the ability of these
surfaces to support the growth of primary human skin cells has been
assessed. Additionally, the ability of these surfaces to modulate
cell migration and morphology has also been investigated. Keratinocytes
and endothelial cells were extremely sensitive to surface chemistry
showing increased viability and migration with an increased number
of carboxylic acid functional groups. Fibroblasts proved to be more
tolerant to changes in surface chemistry; however, these cells migrated
fastest over amine-functionalized surfaces. The novel combination
of comprehensive chemical characterization coupled with the focus
on cell migration provides a unique insight into how a material’s
physicochemical properties affect cell migration