This book describes the development of "smart" biomaterials based on the naturally derived poly-[(R)-3-hydroxybutyrate](PHB). The first part of this book focuses on biodegradable multiblock thermoresponsive poly(ether ester urethane)s consisting of poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG) and PHB. The physical properties as well as applicative studies of these gels such as drug release and tissue engineering are presented. In the second part, the preparation of novel thermoresponsive micelles is presented. Using this copolymer, a thermoresponsive substrate was fabricated by drop-coating with an aqueous polymer solution, and used for the attachment and nonenzymatic temperature-induced detachment of human mesenchymal stem cells and mouse embryonic stem (ES) cells. The promising results from the studies show that these copolymers could be utilized as surface modifiers for tissue engineering applications. In summary, the synthesis of novel ?smart biomaterials? and their application in the fields of drug delivery and tissue engineering are described in this book.