The melting temperatures (Tm) and degrees of crystallinity (Xc, DSC) of each material were determined by differential scanning calorimetry (DSC). As expected, both the melting temperature and crystallinity increased as the amount of BSE decreased (Figure , Table ), regardless of the BSE identity; however, the steric bulk of the Si substituents had a significant impact on the melting temperature and crystallinity of each sample, as has been observed for related orthoester-based PE mimics. For example, EtSi8-co-PE-10 displayed a Tm at 94 ºC and 49.5% crystallinity, while the i Pr analog at the same BSE loading, i PrSi8-co-PE-10, displayed a Tm at 86 °C and only 34.1% crystallinity. Similarly, EtSi8-co-PE-100 had a Tm at 112 ºC and 58.1 % crystallinity, while i PrSi8-co-PE-100 had a Tm at 92 °C and 42.3% crystallinity (Figure , Table ). I.e., for PE mimics at the same BSE loading, the Et-substituted samples consistently exhibited higher melting temperatures and crystallinities than i Pr-substituted samples (Figure ), presumably because the smaller Et substituents do not perturb the hairpin crystal structure of PE to the same extent as i Pr. Compared to its smaller molar mass counterpart, i PrSi8-co-PE-50-HMW displayed a slightly higher Tm (93 ºC) and slightly lower crystallinity (36.2 %). The latter observation is believed to result from the difficulty of long, entangled polymer chains to efficiently pack into a crystal lattice. Powder X-ray diffraction (p-XRD) was used to further support these DSC studies and compare the structures of our materials to HDPE. All samples displayed peaks at similar 2Q values compared to HDPE, indicative of analogous orthorhombic crystal structures (Figure ). The degree of crystallinity (Xc, XRD) was determined by Voigt deconvolution of the amorphous scattering from the crystalline peaks (Figures ); the calculated Xc, XRD values are in excellent agreement with Xc, DSC values (Table ). As expected, the intensity of the peaks also correlates with the degree of crystallinity. Lamellar thickness (L) was calculated according to the Scherrer equation (Equation ) where K is a shape factor (taken to be 0.9), 𝜆 is the X-ray wavelength, 𝛽 is the line broadening at half the maximum intensity, and 𝜃 is the Braggs angle.