the present invention relates to hydrophobic , or water resistant or water repellant , polymers and especially to hydrophobic , or water resistant or water repellant , biodegradable polymers . preferred polymers according to the present invention are polymers based on polylactic acid , polyvinyl , starch , polyacrylic acid , polyester and polymers based on combinations thereof . further , the present invention relates to novel additives and techniques to provide polymers , and especially biodegradable polymers , with improved hydrophobic , water - repellent or water resistant properties .