A facile synthesis route for carboxyaryl-methacrylates: a way to obtain aromatic polyelectrolytes

Abstract

This paper describes a flexible synthetic route for the preparation of the following methacrylic acid derivative monomers with aromatic spacers, including salicylic acid derivatives, in high yields: 2-methacryloyloxybenzoic acid (2-MBA), methyl-2-methacryloyloxybenzoate (M2-MB), 3-methacryloyloxybenzoic acid (3-MBA), methyl-3-methacryloyloxybenzoate (M3-MB), 4-methacryloyloxybenzoic acid (4-MBA), methyl-4-methacryloyloxybenzoate (M4-MB), 4-methacryloyloxy phenyl acetic acid (4-MPAA), methyl-4-methacryloyloxyphenylacetate (M4-MPA) and methyl-4-methacryloyloxyphenylpropionate (M4-MPP). The preparation of the respective aromatic polymers from these monomers by solution free-radical polymerization and their characterization are also described. The position of the substituent in the aromatic spacer ring plays a very important role in the properties of the polymers prepared. While for methyl-ester substitution the glass transition temperature increases from ortho to para isomers, in the case of carboxylic acid substitution this value decreases from ortho to para isomers. The four polymers prepared with free acid groups are hydrophobic polyelectrolytes, as shown by their behavior in aqueous NaCl solutions at different pH values, making them potential candidates for new pH sensitive materials.