Polyamides are one of the most important polymers. Long-chain aliphatic polyamides could bridge the gap between traditional polyamides and polyethylenes. Here we report an approach to preparing sustainable ultra-strong elastomers from biomass-derived long-chain polyamides by thiol-ene addition copolymerization with diamide diene monomers. The pendant polar hydroxyl and non-polar butyrate groups between amides allow controlled programming of supramolecular hydrogen bonding and facile tuning of crystallization of polymer chains. The presence of thioether groups on the main chain can further induce metal–ligand coordination (cuprous-thioether). Unidirectional step-cycle tensile deformation has been applied to these polyamides and significantly enhances tensile strength to over 210 MPa while maintaining elasticity. Uniaxial deformation leads to a rearrangement and alignment of crystalline microstructures, which is responsible for the mechanical enhancement. These chromophore-free polyamides are observed with strong luminescence ascribed to the effect of aggregation-induced emission (AIE), originating from the formation of amide clusters with restricted molecular motions.
A variety of biobased polymers have been derived from
diverse natural
resources. However, the mechanical properties of some of these polymers
are inferior due to low chain entanglement. We report a facile strategy
termed “supramolecular chain entanglement”, which utilizes
supramolecular interactions to create physical cross-linking and entanglements
for polymers with long pendent fatty chains. The ensuing bioplasticsprepared
by mixing copolymers, composed of a plant oil-derived methacrylate
with an acid-containing comonomer as a hydrogen-bonding donorand
poly(4-vinylpyridine) as an entangling chain with a hydrogen-bonding
acceptor show tunable mechanical strength and toughness. These polymer
blends, consisting of ≥90 wt % sustainable sources, exhibit
marked improvement in thermomechanical properties compared with the
viscoelastic nature of the biobased homopolymers. Spectroscopic evidence
and X-ray scattering substantiated the hydrogen-bonding interaction
within the copolymers, while morphological and thermal characterization
was performed to elucidate microstructures of biobased polymers.
Sustainable functional materials
derived from renewable biomass
provide momentum for the communities of polymer science. We report
a supramolecular approach to the preparation of strong biobased polymer
nanocomposites with stimuli-responsive behaviors using soybean oil
(SO) and cellulose nanocrystals (CNCs). SO-derived polymers were modified
with hydroxyl −OH and carboxyl −COOH groups via thiol–ene
click chemistry, facilitating hydrogen-bonding interactions with CNCs
to improve the overall compatibility in the nanocomposites. These
nanocomposites exhibited high tensile strength and maintained high
storage modulus up to 200 °C. Moreover, these nanocomposites
showed a fast and reversible mechanical response to water, an external
stimulus to tune intermolecular hydrogen bonding.
Dynamic metal–ligand coordination creates physical crosslinking and thus improves chain entanglements for enhancing the thermomechanical properties of biobased polymers.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.