Multimodal polymer networks: design and characterisation of nanoheterogeneous PU elastomers

Nanoheterogeneous polymer networks based on polyurethanes (PU) were synthes ised by utilisation of the competition between reactivity, dynamics and pha se separation processes. Oligomeric a,omega-dihydroxyoxolanes (PTHF), 4, 4' -methylene-bisphenylisocyanate (MDI), and trimethylolpropane (TMO) were cho sen as reaction components. In dependence of the mole ratio of these compon ents up to four phases concerning their crosslinking density were formed. B y a partly substitution of incompatible oligomers for PTHF the network stru cture was specically changed including the formation of additional phases. The characterisation of the nanophases was carried out by investigation of the dynamics as reflected by mechanical relaxation spectroscopy. Selected m echanical properties of the samples were measured and discussed using the d educed morphological model.