In the last two decades, hydrogels have been extremely useful in biomedical (specially controlled drug delivery) and pharmaceutical applications mainly due to their water content and rubbery nature, which is similar to natural tissue, as well as their biocompatibility. Polyacrylamide(PAAm) hydrogels exhibit a very high capability to absorb water , they are permeable to oxygen and also possess good biocompatibility ; but are low in hydrolytic stability and tensile strength . Recently colopolymerization of Acrylamide with several new monomers have led to modification for controlled drug delivery applications. The nature of comonomer and hydrogel composition is expected to alter considerably it's swelling and cotrolled release behaviour. Although numerous types of co-monomers have been investigated , only very few studies have been reported (that too in very low range variations)on acrylamide (upto 5%), and acrylic acid (3%).

The present study reports the synthesis of a series of hydrogels based on acrylamide , acrylic acid and butylmethacrylate by varying the composition of all three monomers over three fold for controlled drug delivery of model drugs. The effect of monomer ratios on swelling and drug delivery behaviour of these hydrogels shall be studied in detail. The effect of acrylic acid and AAm content was studied in the range of 20 to 66 % (weight of total monomer) keeping other two monomers constant .Here the BMA portion prevented solubilization of hydrogels due to its hydrophobic nature form, while the acrylic acid imparted higher swelling and environment sensitive nature to the hydrogels and it was found that swelling increased drastically upto four times in non linear fashion.An effort was made to optimize the hydrogels composition for three factors i.e. swelling ratio, handalability, and ability for controlled release. Detailed swelling studies on kinetics for swelling, percentage equilibrium swelling, transport exponent ‘n' and diffusion coefficient ‘D' and effect of pH and temperature on swelling behaviour were conducted. The hydrogels were also characterized by FTIR and SEM, and network parameters, such as average molecular weight between crosslink density were determined to correlate structure property relationship for hydrogels.