Design of polymer networks by variation of precursor structure and crosslinking regime

摘要

The strategy of using preformed functional polymers or oligomers (designed precursors) allows controlling simultaneously the processing and materials properties of the network. The building-up of polymer networks from designed precursors has manifold advantages: (1) chemical environment can be brought into the network by the precursor skeleton; it determines the network durability, thermomechanical properties (T_g) and compatibility with other components; (2) viscosity of the crosslinking system can be adjusted so that it conforms the given technology (casting, coating, molding, etc.); (3) functionality of the precursor and group reactivity can be adjusted to control reaction time and group conversion at he gel point; (4) shrinkage and stress development can be reduced by performing bonds in the precursor; (5) the shape of the precursor can be varied from linear to dendritic or spherical, which controls the viscosity build-up and precursor function in the network (from network chain component to a kind of nanofiller). Network formation and network properties are affected to a great extent by distributions in the number of functional groups, molecular weights and composition of the precursor molecules.