Maleic anhydride, plasma polymerization

Lipid bilayer membranes tethered to plasma-polymerized films as hydrophilic supports were another concept introduced recently [28], The plasma polymerization of maleic anhydride (MAH-PP), e.g., has led to the synthesis of thin polymeric coatings that appear to be suitable to act as a reservoir for an aqueous phase and a cushion for lipid bilayers [29], A crucial requirement for the use of such polymers as water containing supports for lipid bilayer membranes is their adhesion to the substrate. In a previous study [30] covalent binding of MAH-PP films to gold supports was achieved by a self assembled alkylthiol adhesion layer. The previous work has shown that maleic anhydride, when polymerized at a low duty cycle, can behave as a polyelectrolyte. The thin polymer layers were found to have a very low electrical resistance (ca. lOOQcm2) after immersion and subsequent hydrolysis/swelling in aqueous buffer. 

There is a significant difference between copolymerization and codeposition. An example of codeposition is the simultaneous deposition of parylene or a plasma polymer and an evaporated metal, in which each component can be deposited regardless of whether or not the other component is being deposited. Plasma polymerization of a mixture of two hydrocarbons, e.g., CH4 and C2H4, is essentially codeposition of the respective plasma polymers. In contrast, plasma polymerization of gases occurs only in the presence of polymer-forming plasma. This is similar to the copolymerization of maleic anhydride, which does not polymerize, with other vinyl monomers. 

An example of plasma polymerization is acrylic acid coating of PDMS. The polymerized coatings yielded hydrophilic or patterned hydrophilic/ hydrophobic surfaces that were quite stable. These materials were useful in PDMS microchannels in lab-on-a-chip devices or in soft microlithography. Maleic anhydride has also been used in these polymerizations. Photons have also been used to modify surfaces. ... 

The radial distribution function of polymeric carbon prepared from maleic anhydride by plasma deposition by the present authors is shown in Fig. 12 and the peak positions are listed in Table 1. The peaks are situated at 1.44 and 2.9 A, which do not match the peak position of graphite. The peak positions of carbon samples prepared at 600 C are found to be 1.4 and 2.8 A. It is clear from Fig. 12 that there is no layered structure because the region between the second and third peaks is very flat. In addition, the behavior of the radial distribution function with distance cannot be explained using other carbon models, e.g., C 1120, C 340, C 356, and C 519 suggested by Beeman et al. [46,47]. 

Another example relates to the plasma polymerization of maleic anhydride on silicon substrates [55]. After functionalization of the anhydride groups of the polymer with dienophile groups such as allyl amine groups, bicyclo[2.2.1]hept-2-ene groups are attached to the surface via the Diels-Alder cycloaddition of a diene. The cycloaddition of cyclopentadiene or [(trimethylsilyl)methyl]cydopentadiene to the cyclic imide-functionalized plasma polymer is shown in Scheme 1.17. In this case, the extent to which maleic anhydride groups are converted is controllable, such that the number density of functionalized groups can be tailored to comply with the adhesion between different types of solid surface. 

Scheme 1.17 Attachment of bicyclo[2.2.1]hept-2-ene groups to a cyclic imide functionalized thin layer of plasma-polymerized maleic anhydride [55].

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