New bio based polymers : synthesis and polymerization of cystine based macrocycles Redox responsive polymers such as poly(disulfide)s are a versatile class of polymers with potential applications including gene and drug carrier systems. Their degradability under reductive conditions allows for a controlled response to the different redox states that are present throughout the body. Poly(disulfide)s are typically synthesized by step growth polymerizations. Step growth polymerizations however may suffer from low conversions and therefore low molar masses limiting potential applications. The purpose of this thesis was therefore to find and investigate new synthetic routes towards the synthesis of amino acid based poly(disulfide)s. The different routes in this thesis include entropy driven ring opening polymerizations of novel macrocyclic monomers derived from cystine derivatives. These monomers were obtained with overall yields of up to 77% and were analyzed by mass spectrometry as well as by 1D and 2D NMR spectroscopy. The kinetics of the entropy driven ring opening metathesis polymerization (ED ROMP) were thoroughly investigated in dependence of temperature monomer concentration and catalyst concentration. ...