2026 Volume 47 Issue 1 Pages 13-23
The physical properties of compositions containing a styrene-isoprene-styrene (SIS) triblock copolymer and a vinylbenzyl ether-terminated polyphenylene ether (VB-PPE) oligomer were investigated. SIS and VB-PPE were dissolved and mixed in toluene, and the toluene was evaporated to produce composition sheets. Dynamic viscoelasticity evaluation revealed that VB-PPE was selectively soluble in the polystyrene hard phase of SIS. Thermal crosslinking using the vinyl end groups of VB-PPE was then attempted in the SIS compositions. While pure SIS exhibited a significant decrease in storage modulus above 120 °C, the SIS/VB-PPE compositions did not. Furthermore, the gel fraction (degree of crosslinking) of the compositions increased with increasing heat treatment temperature. The vinyl end groups of VB-PPE reacted with each other in the polystyrene hard phase to form semi-interpenetrating polymer networks (semi-IPN), which improved heat and solvent resistance. The phase structure of the SIS/VB-PPE compositions was analyzed using synchrotron radiation smallangle X-ray scattering and transmission electron microscopy. The selective miscibility of VB-PPE into the polystyrene hard phases and the cross-linking changed the phase structures of the compositions.
