The Wettability and Composition of 2-Hydroxyethyl Methacryiate Copolymers

Abstract

Copolymerization of ahydrophilic monomer, 2-hydroxyethyl methacryIate(HEMA), wlth a hydrophobic monomer, styrene(St) or methyl methacrylate(MMA), was studied. In the case of HEMA-MMAsystem, copolymer composition was determined by NMR spectra in pyridine. Monomer reactivity ratios were determined as given in the following table. HEMA-St γ ₁(HEMA)0.85 γ ₂0.33HEMA-MMA γ ₁(HEMA)0.66 γ ₂0.86Films of copolymers andb lendmers were cast from DMF solutions. They make contact angles with water. In the case of blendmers, contact angles vary graduaUy with composition. Contrary to blendmers, contact angles of copolymers rernarkably change with HEMA mole fraction to bring about a rise of about 0.8 in HEMA-St system, and about O.5 in HEMA-MMA system. The difference in wettability between copolymers and blendmers was considered to benatural, since hydrophilic and hydrophobic functions were influenced not only by the composition but also by the microstructure to the polymers.