Hard-soft thiol-ene materials without interfacial weakness

Thiol-ene materials are a series of materials that can be crosslinked using a suitable photo-initiator and a UV light source. An advantage of thiol-ene materials is that they can be tailored to have specific mechanical properties by controlling the stoichiometry of the mixtures. By combination of different reactants, it is therefore, in principle, possible to prepare monoliths with greatly varying mechanical properties from essentially the same material.

In this paper, we prepared an alternating hard and soft thiol-ene material with a sharp solid interface. Tetrakis (3-mercaptopropionate) (PETMP) with 1, 3, 5-triallyl-1, 3, 5-triazine-2, 4, 6(1H, 3H, 5 H)-trione (TATATO) as the hard segment exhibited strong tensile and compressive strength but had low elongation and weak bending stiffness.

A mixture of PETMP and trimethylolpropane diallyl ether (TMPDE) was selected as the soft segment. After stretching at 0.001 s−1 using a filament stretching rheometer (FSR), the soft segment fractured at the strain of 21%, while the interface of the materials was strong enough to prevent cracking.