Plasma treatments polymeric substrates

The following commercial polymeric substrates have been investigated low density polyethylene (PE, Dow Chemical Canada Inc.) polyimide (PI, DuPont Kapton H), polytetrafluoroethylene (PTFE, DuPont Teflon), polycarbonate (PC, Mobay Corp.) and surface-lubricated (with glycerol ester) polyvinylchloride (FVC, Canadian Occidental Petroleum Ltd). After plasma treatment, the samples were exposed to ambient atmosphere for 10 - 30 minutes while being transferred to the following... 

Low-temperature plasma processes, such as gas plasma treatment and plasma polymerization, have unique advantages in that active (depositing) species strongly interact with the surface of the substrate and modify the surface state. An ultrathin layer of plasma polymer, e.g., thickness less than 50 nm, can be viewed as a new surface state because such a thin layer does not develop a characteristic bulk... 

T/F plasma polymer was also selected to improve the adhesion of different spray paints to IVD Al-coated panels. As presented in Table 32.3, T/F plasma polymer [DC plasma-polymerized trimethylsilane (TMS) followed by hexafluoroethane (HFE)] gave rise to such a strong adhesion of E-coat that could not be stripped off after 24-h application of Turco solution. Since the formation of mechanical interlocking between primers and porous IVD surfaces could conceal the role of plasma treatment in enhancing adhesion, bare 7075-T6 aluminum alloy panels with smooth surfaces were first used as substrate to examine the effect of plasma treatment on the adhesion of spray paints. 

The corrosion protection of plasma interface-engineered coating systems relies on the tenacious water-insensitive adhesion and good barrier characteristics of the coatings [3]. DC cathodic polymerization and plasma treatment have been demonstrated as efficient in improving the primer adhesion to metallic substrates. 

Besides the advantageous features described earlier, DC cathodic plasma polymerization of TMS mixed with argon also provides an opportunity to combine the two processes of TMS deposition and second plasma treatment into a single step. TMS plasma coating thus produced also maintains excellent corrosion protection properties on the aluminum alloy substrates. 

The same protocol was used for the grafting from procedure to graft mixed brushes on to polymeric substrate. Plasma treatment was used to introduce hydroxyl (oxygen plasma) and amino (NH3 plasma) functional groups on to the polymeric surfaces and then Cl-ABCPA and two different homopolymers were grafted by polymerization from the functionalized surface. 

In the grafting from approach, a surface, that was previously activated e.g. by plasma treatment, is exposed to a monomer solution (Huang et al. 2003). A more simple, one-step procedure is to inadiate a polymeric surface like TCP, which is covered with the monomer solution, by an electron beam (Yamada et al. 1990). Alternatively, ultraviolet light and a photosensitiser can be utilised to initiate polymerisation and cross-linking (Curti et al. 2005). A completely different route to prepare thin SRP coatings with good adhesion to solid substrates is plasma polymerisation (Biederman and Osada 1992). In this case, NIPAAm is used as a precursor in a plasmachemical thin film deposition process (Cheng et al. 2005 Pan et al. 2001). 

Contrary to the monomer-based techniques described so far, low-pressure plasma immobilisation allows to permanently attach stimuli-responsive polymer films with a thickness of a few nanometers on polymeric substrates using an argon discharge. At appropriate treatment parameters, covalent fixation is achieved while important properties of the immobilised polymer like the thermo-responsive behaviour are preserved (Schmaljohann et al. 2004 Nitschke et al. 2004). 

This article describes some of the recent progress in the area of plaana polymerization and plasma treatment. It is not intended to be an exhaustive overview of the field, but instead a summary of the highlights of research studies in this field as perceived by the authors. Fundamentals of plasma physics and chemistry are also briefly described in order to hdp understanding of plasma processing in the gas phase and on the substrate. 

Plasma treatment of microchannels can be useful for improving the functionality of microdevices. For example, previous studies have shown that PDMS microchannels can be made hydrophilic by the addition of silane molecules with polar head groups [6]. In this process (3-mercaptopropyl)trimethoxysilane (3-MPS) was absorbed to PDMS to increase the hydrophilic properties of microchannels. Additionally, plasma polymerization has been used to induce in the long-term hydrophilic surface modification by covalently bonding a polymer layer to the surface. Barbier et al. [7] describe a method based on plasma polymerization modification with acrylic acid coatings. First, argon plasma pretreatment was used to activate trace oxygen molecules in the chamber, which partially oxidize the top layer of the substrate. This step cross-linked the surface to reduce ablation of silicon... 

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