Poly(2-hydroxyethyl methacrylate) and all copolymers of poly-hema fibers

Abstract

Hydrogels are polymers that swell in water and are hydrophilic. The degree and nature of cross linking and the crystallinity of the polymer are responsible for its properties in the swollen state, and the degree to which it imbibes water without the loss of shape is important in many natural hydrogel. Some natural hydrogels are used in the textile industry, pulp and paper production, artificial silk, cellulosic membranes, and biomedical applications. Synthetic hydrogels are used in soft lenses, prosthetic materials and membranes for controlled drug delivery. Poly-HEMA (poly 2 hydroxylthyl methacrylate) is the most widely used hydrogel. The properties of poly HEMA can be modified by cross linking to a certain degree but its hydrophilicity can be increased by the introduction of a second hydroxyl using various monomers. Also its strength will also improve by the addition of a comonomer. These copolymers yielding increase hydrophilicity and strength are exhibited in soft hydrogel films, flexible even in the dry state. Copolymers of HEMA have been utilized in drug delivery systems where the drug diffusion is controlled by the type and ratios of comonomers used together with certain cross linking agents. Comonomers with anionic fixed charges are incorporated in poly HEMA chains, e.g. Methacylic acid (MAA) and acrylic acid(AA). The gels formed containing MAA used in soft contact lenses absorb much more protein than any other gels. Homopolymer poly HEMA fibers and various copolymers of poly HEMA have been combined with standard cosmetic, skin, and nail formulations to provide excellent, enhanced properties to the human body.