Whilst it has been observed that altering the molar mass of a polymer can affect the Tg in linear PDMS, the Tg for both PDMS-OH polymers was found to be identical (~ -125 °C). The appearance of Tcc at ~ -90 °C is related to experimental conditions, where upon cooling the polymer too quickly, not all crystallites have time to form before reaching the Tg. When heating again above the Tg, any nucleation sites will start to recrystallise. Assuming that all crystallites have formed at the Tcc, the total enthalpy of crystallisation (ΔHc-total) would be the sum of ΔHc and ΔHcc, allowing for the crystalline fraction (χc) to be estimated using enthalpy change of 100% crystalline linear PDMS (ΔH100% = 37.4 J g -1 ). The results conclusively show that HPDMS-OH has a higher crystalline fraction than LPDMS-OH (0.73 vs 0.59) assigned to the much higher molar mass. At higher temperatures, the crystallites in both PDMS-OH polymers start to melt as evidenced by the bimodal endothermic peak (Tm). The bimodal melt is routinely observed for PDMS and has been suggested to be related to the melt of different metastable crystallites. Tm used here is the average between the two peaks and for LPDMS-OH and HPDMS-OH are -49 and -38 °C. It is also worth noting here that the two peaks (about -50 and -40 °C) change in heat flow intensity between the two PDMS-OH polymers, believed to be the result of different molar masses. LPDMS-OH exhibited a lower Tm than HPDMS-OH, yet ΔHm for LPDMS-OH is more than twice its ΔHc-total, whereas ΔHm for HPDMS-OH does not significantly change from its ΔHc-total. The increase in ΔHm for LPDMS-OH compared to ΔHc-total is indicative of a underlying supramolecular structure, previously assigned to hydrogen bonding interactions between the hydroxy end-groups. While the two PDMS-OH polymers exhibited comparable thermal properties, the PBS elastomers, conversely, exhibited stark differences between the lower and higher molar mass samples. The thermogram of LPBS is completely different to the LPDMS-OH thermogram, where all transitions apart from the Tg are no longer observable. The loss of most thermal transitions in the LPBS is further evidence for the formation of a crosslinked network lacking significant crystalline structure. In contrast, HPBS revealed very similar thermal transitions to HPDMS-OH with the only difference being a small decrease in ΔHcc (1.0 vs 3.2 J g - 1