), resulting in a smaller χc (0.68 vs 0.73). The resemblance observed between the HPDMS-OH and HPBS thermograms strongly suggests that HPBS has preserved a nearly identical microstructure, likely attributed to the limited number of crosslinking sites. As a result of the differences in polymer networks between LPBS and HPBS, the thermal transitions upon blending 1 wt% P3HT into each elastomer are very different, in both the heating and cooling cycle (Figure ). P3HT showed Tm and Tc peak maxima at 235 and 199 °C with an associated ΔHm of 14.9 J g -1 and and ΔHc of 14.3 J g -1 respectively. Introducing 1 wt% of P3HT into HPBS shifted the Tm, Tc and Tcc of HPBS by ~5 °C to higher temperatures, while ΔHm remained unchanged, ΔHc for the HPBS:P3HT blend decreased (14.3 J g -1 ) and ΔHcc increased (16.5 J g -1 ). The appearance of a Tcc in the thermogram, as well as the alteration in enthalpy change between the pure elastomer and the blend indicates that the addition of P3HT has a profound effect on the crystallisation kinetics of the HPBS:P3HT blend. The absence of a defined crystallisation peak for P3HT provides evidence that P3HT has blended well with HPBS. This is in good agreement with the solution UV-Vis absorbance results where an increasing HPBS content did not induce any strong P3HT aggregation yet is conflicting to the images of the blends (Figure ). We therefore suggest that HPBS and P3HT are blending well on the microscale, however on the macroscale, relatively large P3HT rich domains are phase separating. Contrary to the P3HT:LPBS blend where the introduction of 1 wt% P3HT into LPBS led to the presence of a new endothermic and exothermic peak in the respective heating and cooling cycles. The peaks at 120 °C and 98 °C are assigned to the Tm and Tc of P3HT crystallites within the blend. Their appearance suggests that P3HT has not blended well with the LPBS, which again is in agreement with the solution UV-vis absorbance experiments and the increased RED value obtained from the HSP.