Unraveling substituent effects on the glass transition temperatures of biorenewable polyesters

Abstract

Converting biomass-based feedstocks into polymers not only reduces our reliance on fossil fuels, but also furnishes multiple opportunities to design biorenewable polymers with targeted properties and functionalities. Here we report a series of high glass transition temperature (Tg up to 184 °C) polyesters derived from sugar-based furan derivatives as well as a joint experimental and theoretical study of substituent effects on their thermal properties. Surprisingly, we find that polymers with moderate steric hindrance exhibit the highest Tg values. Through a detailed Ramachandran-type analysis of the rotational flexibility of the polymer backbone, we find that additional steric hindrance does not necessarily increase chain stiffness in these polyesters. We attribute this interesting structure-property relationship to a complex interplay between methyl-induced steric strain and the concerted rotations along the polymer backbone. We believe that our findings provide key insight into the relationship between structure and thermal properties across a range of synthetic polymers.

Triblock polyester thermoplastic elastomers with semi-aromatic polymer end blocks by ring-opening copolymerization

“…The values are also consistent with previously reported T g values for PE which were in the range 130-146 C (M n ¼ 10-20 kg mol À1 ). [48][49][50] For TBPE-1 to -5, the T g,PE values increase to the expected values for entangled chains implying better phase separation with increasing N, a nding which is fully consistent with other phase-separated block polymers. 11 Likewise, for the so PDL block, the T g decreases from À49 to À51 C from TBPE-1 to TBPE-5 as the M n increases from 27 to 65 kg mol À1 .…”

“…[43][44][45][46] For example, the ROCOP of phthalic anhydride (PA) with cyclohexene oxide (CHO) affords a polyester with a T g from 133-146 C (depending on molar mass). [47][48][49][50] Both PA and CHO are existing commercial chemicals already used at scale in the polymer industry and, specically, their use to make new polymers would obviate costly, time-consuming, and complex commercialization required for completely new monomers. Currently both CHO and PA are manufactured from petroleum but routes to CHO from 1,4-cyclohexadiene, a waste product of plant oil selfmetathesis, and to PA from corn stover are reported.…”

Easy access to oxygenated block polymers via switchable catalysis

“…The resulting triblock polymers are all amorphous with glass-transition temperatures from −40 to 34 °C, depending on the structure of the anhydride (Supplementary Fig. 17) 47 . The anhydride scope experiments allow two further guidelines: (iii) Anhydrides showing minimal steric hindrance result in broadened molar mass distributions, perhaps due to transesterification side-reactions; and (iv) Well-defined block polymers result when using sterically encumbered bi- and tricyclic anhydrides 43 .…”

Butterfly‐Shaped Thiophene‐Pyridine Hybrids: Green Electroluminescence and Large Third‐Order Optical Nonlinearities

“…The higher T g of 2TPA-TPY and 2CBZ-TPY compared to that of 2TPY-TPA and 2TPY-CBZ is attributed to the presence of bulky side groups in 2TPA-TPY and 2CBZ-TPY, which hinders the rotational flexibility, thereby increases the T g . [38] The TGA results reveal that the molecules possess extremely good thermal stabilities with the high degradation temperatures. The decomposition temperature (T d ) of 2TPA-TPY and 2CBZ-TPY (corresponding to 5 % weight loss) is observed at 426 and 432°C, respectively, whereas, the T d of 2TPY-TPA and 2TPY-CBZ is observed at 417 (corresponding to 20 % weight loss) and 428°C (corresponding to 10 % weight loss), respectively.…”