Biodegradable polymers are designed to degrade into simpler components like water, CO₂, Nitrogen etc. upon disposal by the action of living organisms. Extraordinary progress has been made in the development of practical processes and products from polymers such as starch, cellulose, and lactic acid. The need to create alternative biodegradable water-soluble polymers for down-the-drain products such as detergents and cosmetics has taken on increasing importance. Aliphatic polyesters are one of the important classes of biodegradable polymer. Example. Poly β-hydroxybutyrate – co-β-hydroxy valerate (PHBV)