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.
Octahydro-2,5-pentalenediol
(OPD), is a compelling citric acid–based
bicyclic diol with excellent rigidity and thermal stability. Herein,
a series of copolycarbonates (co-PCs) were synthesized, starting from
OPD, 1,4-cyclohexanedimethanol (CHDM), and diphenyl carbonate (DPC).
All polycarbonates are amorphous with glass transition temperatures
increased when increasing the content in OPD units. Dynamic mechanical
analysis (DMA) revealed the sub T
g β-relaxations
at low temperatures originating from the CHDM conformational transition,
indicative of the possibility of impact-resistance. Morphological
analysis of the fracture surfaces revealed the toughening mechanism
under tensile was shear yielding of the matrix triggered by internal
cavitation. The incorporation of OPD steadily increased the Young’s
modulus, from 482 to 757 MPa, with the OPD fraction increased from
0 to 30 mol %. As the OPD content further increased, a “ductile-to-brittle”
transition occurred due to the low number-average molecular weight
(M
n) and the low entangled strand density
(high entanglement molecular weight).
(1R,3S)-1,2,2-trimethylcyclopentane-1,3-dimethanol
(TCDM) is a rigid alicyclic diol prepared by oxidation and subsequent
reduction of naturally occurring camphor. To improve the low glass
transition temperature (T
g), slow degradation
rate, and brittleness of poly(butylene succinate) (PBS), two series
of PBS copolyesters based on TCDM were synthesized using two different
methods. Random copolymerization (RC) of a mixture of TCDM, 1,4-butanediol
(BDO), and 1,4-succinic acid (SA) afforded random PBS copolyesters,
while reactive blending (RB) of pure PBS and PTS (homopolyester based
on TCDM and SA) afforded PBS copolyesters with blocklike chemical
microstructures. For both series, the insertion of TCDM units resulted
in elevated thermal stability and higher T
g values compared to those of neat PBS. The RB-prepared copolyesters
displayed higher melting points, a higher degree of crystallinity,
and higher mechanical properties with respect to those of their random
counterparts obtained by RC. The incorporation of TCDM units enhanced
the hydrolytic degradation rates for both series, which is more pronounced
for the RC-prepared copolyesters. Overall, this work confirmed the
effectiveness of the RB technology in preparing high-performance biopolymers
such as improving the sustainability of raw materials, achieving high T
g values, and promoting the mechanical strength
and biodegradability as well.
Two new bioderived diamines with two cis-fused cyclopentane ring structure, bis(4-aminophenyl) (octahydropentalene-2,5-diyl)dicarbamate (OAC) and 4,4'-((octahydropentalene-2,5-diyl)bis(oxy))dianiline (OOD), were designed and synthesized from natural citric acid for the first time. Two series...
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