We
have prepared a series of 12
d
-isosorbide-2-alkanoate-5-methacrylate
monomers as single regioisomers with different pendant linear C2–C20
alkanoyl chains using biocatalytic and chemical acylations. By conventional
radical polymerization, these monomers provided high-molecular-weight
biobased poly(alkanoyl isosorbide methacrylate)s (PAIMAs). Samples
with C2–C12 alkanoyl chains were amorphous with glass transition
temperatures from 107 to 54 °C, while C14–C20 chains provided
semicrystalline materials with melting points up to 59 °C. Moreover,
PAIMAs with C13–C20 chains formed liquid crystalline mesophases
with transition temperatures up to 93 °C. The mesophases were
studied using polarized optical microscopy, and rheology showed stepwise
changes of the viscosity at the transition temperature. Unexpectedly,
a PAIMA prepared from a regioisomeric monomer (C18) showed semicrystallinity
but not liquid crystallinity. Consequently, the properties of the
PAIMAs were readily tunable by controlling the phase structure and
transitions through the alkanoyl chain length and the regiochemistry
to form fully amorphous, semicrystalline, or semi/liquid crystalline
materials.
A bicylic diketone is derived from citric acid and readily ketalized with trimethylolpropane to produce a spirodiol monomer for rigid, high-molecular weight, melt processable biobased polycarbonates.
We here report on
the synthesis and polymerization of nitrile-containing
methacrylate monomers, prepared via straightforward nitrilation of
the corresponding lignin-inspired aldehyde. The polymethacrylates
reached exceptionally high glass transition temperatures (
T
g
values), i.e., 150, 164, and 238 °C for
the 4-hydroxybenzonitrile, vanillonitrile, and syringonitrile derivatives,
respectively, and were thermally stable up to above 300 °C. Copolymerizations
of the nitrile monomers with styrene and methyl methacrylate, respectively,
gave potentially melt processable materials with tunable
T
g
values and enhanced solvent resistance. The use of lignin-derived
nitrile-containing monomers represents an efficient strategy toward
well-defined biobased high
T
g
polymer
materials.
A series of regioisomeric isosorbide mono-epoxides, as well as diastereomerically pure mono-epoxy derivatives, have been prepared and studied. Anionic ring-opening polymerization of methoxy-capped monomers produced linear polyethers tethered with isosorbide...
Incorporating rigid
cyclic acetal and ketal units into polymer
structures is an important strategy toward recyclable high-performance
materials from renewable resources. In the present work, citric acid,
a widely used platform chemical derived from biomass, has been efficiently
converted into di- and tricyclic diketones. Ketalization with glycerol
or trimethylolpropane afforded rigid spirodiols, which were obtained
as complex mixtures of isomers. After a comprehensive NMR analysis,
the spirodiols were converted into the respective di(meth)acrylates
and utilized in thiol–ene polymerizations in combination with
different dithiols. The resulting poly(β-thioether ester ketal)s
were thermally stable up to 300 °C and showed glass-transition
temperatures in a range of −7 to 40 °C, depending on monomer
composition. The polymers were stable in aqueous acids and bases,
but in a mixture of 1 M aqueous HCl and acetone, the ketal functional
groups were cleanly hydrolyzed, opening the pathway for potential
chemical recycling of these materials. We envision that these novel
bioderived spirodiols have a great potential to become valuable and
versatile bio-based building blocks for several different kinds of
polymer materials.
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