To address the poor thermal stability of isohexides while at the same time retain rigidity, we developed a novel bicyclic diol octahydro-2,5-pentalenediol (OPD) from naturally occurring citric acid in this study. Owing to the bicyclic skeleton composed of two fused cyclopentane rings, OPD is supposed to have perfect rigidity but higher thermal stability compared to isohexides. Herein, OPD was first converted to octahydro-2,5-pentalenediol bis­(methyl carbonate) (OPBMC) by reacting with dimethyl carbonate. The absolute stereochemistry of OPBMC was investigated by 2D 1H NMR and 13C NMR as well as single crystal X-ray diffraction. By polymerization of OPBMC with several aliphatic diols [1,8-octanediol (A8), 1,10-decanediol (A10), and 1,12-dodeacnediol (A12)] and alicyclic diols [1,4-cyclohexane­dimethanol (CHDM), 1,2,2-trimethyl­cyclopentane-1,3-dimethanol (TCDM), and octahydro-2,5-pentalenediol (OPD)], a series of bio-based copolycarbonates (co-PCs) with intriguing properties were synthesized. NMR spectra revealed that the stereochemistry of OPBMC was preserved after polymerization. Both differential scanning calorimetry and wide-angle X-ray diffraction analyses revealed that co-PCs made from A8, A10, A12, and OPD are semicrystalline, while co-PCs based on CHDM and TCDM are amorphous. A relatively high T 5% of 276 °C and outstanding high T g up to 80.4 °C were detected for fully OPD-based co-PC, confirming the excellent thermal stability and rigidity of OPD. This work addresses some critical needs for high performance polymers such as improving the sustainability of raw materials and achieving both high T g values and thermal stability.

A series of renewable polyesters were synthesized derived from 10-undecenoic acid and vanillic acid. An outstanding feature is that the incorporation of vanillic acid segments into the polyester backbone results in improved mechanical properties.

5Two series of bio-based poly(ether-ester)s from vanillic acid and linear α,ω-diols HO-(CH 2 ) m -OH (m = 2, 3, 4, 10) have been successfully synthesized by the direct esterification method. These poly(ether-ester)s were characterized using FTIR, 1 H-NMR, and size exclusion chromatograph (SEC). Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) were used to study their thermo-mechanical properties. The poly( ether-ester)s had weight-average molecular 10 weights (M w ) in the range of 16600 to 78700 g mol -1 and polydispersities between 1.39 and 2.00. All of the bio-based poly(ether-ester)s exhibited amorphous features with their glass transition temperatures (T g s) ranging from 5 to 67 °C. The stress-strain parameters showed that the mechanical properties of these poly(ether-ester)s were excellent. The Young's modulus and elongation at break of the poly(ether-ester)s in this series were found in the range of 95-228 MPa and 14.9-311%, respectively.

In this work, alicyclic (1R,3S)-1,2,2-trimethylcyclopentane-1,3-dimethanol (TCDM), derived from natural camphor, was copolymerized with linear α,ω-diacids, terephthalic acid (TPA), and 2,5-furandicarboxylic acid (FDCA), affording a series of polyesters with functional properties. 2D NMR spectroscopy revealed that the stereoconfiguration of TCDM was preserved after polymerization. The TCDM polyester based on TPA showed high thermostability, high T g value (115 °C), high modulus (1.3 GPa), and high ultimate strength (29.8 MPa). The TCDM polyester based on 1,4-succinic acid exhibited excellent ductility and resilience. Lastly, the rigidity analysis based on van Krevelen’s group contribution method, coupled with the comparisons between TCDM- and sugar-based polyesters, confirmed that TCDM is a highly reactive and rigid diol. Results indicate that TCDM polyesters are suitable for a wide range of applications, including hot-filled containers and transparent packaging materials. This work addresses some critical needs for high performance biopolymers such as achieving high T g values, high thermostability, and high transparency.

Here we present a series of homopolycarbonates (homo-PCs) and copolycarbonates (co-PCs) based on a novel bicyclic diol octahydro-2,5-pentalenediol (OPD) from naturally occurring citric acid and bis­(hydroxyethyl ether) of bisphenol A (BHEEB), synthesized by melt polycondensation. The recently developed OPD has been shown to be a highly rigid and thermally stable building block suitable for the construction of performance polymers. BHEEB, which was obtained from the chemical recycling of BPA-PC, was used to compensate for the low reactivity of OPD and to modify the brittleness of polycarbonate (PC) solely based on OPD, without compromising other properties. The single crystal of the endo-endo isomer of OPD was deliberately obtained, and its absolute stereochemistry was unambiguously identified by single-crystal X-ray diffraction for the first time. The polymers had M n in the 10 100–20 000 g mol–1 range and gradually decreased with increasing OPD content. NMR analyses revealed the random structures of the co-PCs and the molar content of OPD in all cases were lower than its corresponding feeds. Interestingly, in contrast with the semicrystalline poly­(octahydro-2,5-pentalenediol carbonate) (abbreviated as pre-POC) prepared in a different protocol in our previous article, poly­(octahydro-2,5-pentalenediol carbonate) (abbreviated as POC) in this study exhibited amorphous feature with a lower T g of 74.5 °C. A “ductile–to–brittle” transition occurred with increasing OPD content in the PBC chains, which can be ascribed to their low molecular weights and the low entangled strand density due to the rather stiff polymer chains. This work combines chemical recycling and the biobased polymer together, which would bring a feasible way to satisfy the demands of sustainability.