Brush polymethacrylic acid

In one example polymer segment density profiles of weak polyacid brushes consisting of polymethacrylic acid (PMAA) chains were investigated as a function of the pH of the environment by means of multiple-angle ellipsom-etry [68]. The polymer brushes were prepared by surface-initiated polymerization of methylacrylic acid as described above. 

Fig. 22 Swollen thickness of a polymethacrylic acid brush attached to a planar lanthanum oxide surface as a function of the pH of the solution. The thickness is determined by FT analysis (closed symbols) and by Fresnel modeling (open symbols) of ellipsometric data. For details see text...

In the following text we focus on cylindrical brushes prepared by polymerization of macromonomers, in particular on two systems. First, cylindrical brushes consisting of poly-2-vinylpyridine side chains and a poly-methacrylic main chain are discussed these were converted into cationic polyelectrolyte brushes by quaternization of the pyridine units by alkyl halides. The second system comprises sulfonated anionic cylindrical brushes, i.e. polymacromonomers with polystyrene side and main chains and polymacromonomers with polymethacrylic main and polymethacrylic acid side chains. 

An alternative (and perhaps more efficient) polymeric surfactant is the amphipathic graft copolymer consisting of a polymeric backbone B (polystyrene or polymethylmethacrylate) and several A chains ( teeth ) such as polyethylene oxide. The graft copolymer is referred to as a comb stabilizer—the polymer forms a brush at the solid/liquid interface. The copolymer is usually prepared by grafting a macromonomer such as me-thoxy polyethylene oxide methacrylate with polymethyl methacrylate. In most cases, some polymethacrylic acid is incorporated with the polymethylmethacrylate backbone this leads to reduction of the glass transition of the backbone, which makes the chain more flexible for adsorption at the S/L interface. Typical commercially available graft copolymers are Atlox 4913 and Hypermer CG-6 (ICI). 

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