Chemical functionalization of plasma polymer surfaces

Abstract

The work in this thesis has concentrated upon the chemical functionalization of plasma polymer surfaces. The ability to deposit and then funotionalize these surface layers has practical implications for many different areas, such as biomedical uses and heterogeneous catalysis and many different functional groups can be attached to surfaces using the plasma polymer layer as an intermediate. A variety of substrates, from glass to polymer films have been studied. Two different monomers have been studied in this work. The majority of work was carried out using a maleic anhydride plasma polymer (MAPP), which can be deposited from maleic anhydride under pulsed plasma conditions. The second monomer used was allylamine, whose plasma polymer has previously been studied as a biomedical layer. For both of these monomers, a variety of functionalization reactions have been studied. In the case of the anhydride group the key reaction is that which occurs between the anhydride group and amines. The reaction of amines with the anhydride is through a ring opening of the anhydride group, leading to the formation of amic acid groups. This part of the thesis allowed an understanding of the mechanism of vapour phase reactions to be acquired. Once this understanding had been achieved, many more amine containing groups were studied, such as poly(amidoamine) (PAMAM) dendrimers, functionalized polystyrene particles, polycations and molecules containing double bonds were reacted with the MAPP surface. These functional molecules can be used for immobilizing metal particles, stabilizing colloids adhering surfaces and Diels-Alder reactions. In the case of the allylamine, a variety of different functionalization routes we studied. Formation of amide groups at the surface was studied using heptafluorobutryl chloride and carboxylic acid functionalized polystyrene beads. The ability of the allylamine plasma polymer layer to act as a polycationic layer was investigated with an anionic polymeric dye, DNA and gold colloids.