To investigate the thermal stability of homopolymers, TGA was performed in the temperature range of 30 °C to 900 °C (Fig. ). Around 220 °C, 3-4 % mass loss was observed in all homopolymers, which is consistent with the Boc weight percent of homopolymers. Onset temperature of major mass loss Td of all homopolymers is around 350 °C, which is consistent with widely reported thermal stability of POxbased polymers. DSC measurements were performed from -50 °C to 190 °C in order to determine the thermal transitions of the homopolymers. In the given temperature range, no melting temperature (Tm) of homopolymers was observed (Fig. ), which may be connected to the rather short chain length. The glass transition temperature (Tg) of pEtEtOx series homopolymer, p R EtEtOx, p S EtEtOx and p RS EtEtOx, are very similar (around 80 °C), i.e., the different chirality of pEtEtOx series homopolymers, as expected, does not affect chain segment mobility (Table ). Similarly, in the pPrMeOx series, of the Tg values (around 55 °C) for p R PrMeOx, p S PrMeOx and p RS PrMeOx are essentially identical. Clearly, the Tg of pPrMeOx series is lower than that of pEtEtOx, which signifies higher chain segment mobility for pPrMeOx than pEtEtOx. There has been some research on the thermal properties of various POx and poly(2-alkyl-2-oxazines) (POzi) (Table ). Two conclusions were drawn in this previous work: the Tg of POx decreased linearly with increasing carbon number in the side chain (from 1 to 5 carbon atoms), while linear POzi have lower Tg than the POx with same side-chain, which is attributable to the additional methylene unit in the main chain. Previously reported p R BuEtOx ([M]/[I]=60, Tg ≈52 °C ) has two methylene groups more in side-chain than p R EtEtOx and a Tg about 30 °C lower than the Tg of p R EtEtOx (Tg ≈ 82 °C), which shows that with increasing number of carbon atoms in the side-chain the Tg also decreases for main-chain branched POx. Besides, the Tg of pEtEtOx is 20 °C higher than that of pEtOx, pPrMeOx has a 15 °C higher Tg than poly(2-propyl-2oxazoline) (pPrOx), and the Tg of pEtEtOx is about 30 °C higher than the Tg of pPrMeOx. It should be noted, that for the 2-substituted POx, polymers with higher DP values were investigated, suggesting that at similar DPs, the difference would be even more pronounced. In addition, poly(2-ethyl-4-methyl-2oxazoline) (pEtMeOx) has a reported Tg of 75 -80 °C, which is basically identical with value found here for pEtEtOx. It is apparent that the presence of an additional methylene group at the polymer backbone branch, compared to the amide side chain, significantly impedes the macromolecular segment mobility. Also, increasing the length (from C1 to C2) of the side chain branching directly from the polymer backbone does not decrease the Tg, which stands in contrast to the amide side chain. However, it would be interesting to see how the Tg evolves for longer side chains (≥ C3) branching from the main chain. Bloksma et al. investigated the enantiopure polymer p R BuEtOx, p S BuEtOx and racemic p RS BuEtOx via Xray diffraction (XRD). The enantiopure polymers were found to be semicrystalline, while the racemic polymer was amorphous. However, pEtEtOx and pPrMeOx with short side-chain and main-chain branches have not been investigated using XRD before. Therefore, XRD measurements were performed on the pEtEtOx and pPrMeOx series at room temperature. All the homopolymers showed broad bands (Fig. ),