Multimodal polymer networks: design and characterisation of nanoheterogeneous PU elastomers

Nanoheterogeneous polymer networks based on polyurethanes (PU) were synthesised by utilisation of the competition between reactivity, dynamics and phase separation processes. Oligomeric α,ω‐dihydroxyoxolanes (PTHF), 4,4′‐methylene‐bisphenylisocyanate (MDI), and trimethylolpropane (TMP) were chosen as reaction components. In dependence of the mole ratio of these components up to four phases concerning their crosslinking density were formed. By a partly substitution of incompatible oligomers for PTHF the network structure was specifically 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 mechanical properties of the samples were measured and discussed using the deduced morphological model.