Will it blend? Exploring the viscoelastic characteristics of P3HT-polyborosiloxane blends towards flexible electronic materials

Organic semiconducting polymers blended into elastomeric materials has shown to be a successful method for improving flexibility designed for wearable electronics. One such elastomer that has not been readily explored in combination with an organic semiconducting polymer is polyborosiloxane (PBS). PBS shows remarkable viscoelastomeric properties, due to the borate ester groups that crosslink the siloxane backbones, demonstrating a dynamic covalent crosslinking mechanism. The detailed study presented here showcases the properties of two different PBS elastomers and the effect of blending a well-known organic semiconducting polymer, poly(3-hexylthiophene) (P3HT). Compatibility studies find that one elastomer blends more favourably than the other due to differences in the crosslinking density leading to the formation of P3HT crystallites within the blend. The viscoelastic properties of the PBS:P3HT blends are studied through detailed rheological experiments and the relaxation processes are discussed.