Anisur Rahman

Plant Oil-Derived Epoxy Polymers toward Sustainable Biobased Thermosets

Epoxy polymers (EPs) derived from soybean oil with varied chemical structures are synthesized. These polymers are then cured with anhydrides to yield soybean-oil-derived epoxy thermosets. The curing kinetic, thermal, and mechanical properties are well characterized. Due to the high epoxide functionality per epoxy polymer chain, these thermosets exhibit tensile strength over an order of magnitude higher than a control formulation with epoxidized soybean oil. More importantly, thermosetting materials ranging from soft elastomers to tough thermosets can be obtained simply by using different EPs and/or by controlling feed ratios of EPs to anhydrides.

Cationic Metallo‐Polyelectrolytes for Robust Alkaline Anion‐Exchange Membranes

Chemically inert, mechanically tough, cationic metallo-polyelectrolytes were conceptualized and designed as durable anion-exchange membranes (AEMs). Ring-opening metathesis polymerization (ROMP) of cobaltocenium-containing cyclooctene with triazole as the only linker group, followed by backbone hydrogenation, led to a new class of AEMs with a polyethylene-like framework and alkaline-stable cobaltocenium cation for ion transport. These AEMs exhibited excellent thermal, chemical and mechanical stability, as well as high ion conductivity.

Renewable atom-efficient polyesters and thermosetting resins derived from high oleic soybean oil

We report an atom-efficient approach to the preparation of sustainable polyesters and their corresponding thermosetting resins (RESINs) from renewable plant oils. Specifically, a diol monomer, oleic acid diethanol amide (OADEA), was derived from high oleic soybean oil (HOSBO) via a powerful amidation reaction. A series of OADEA-derived polyesters were prepared by condensation polymerization of this diol monomer with four different diacids. These polyesters were then epoxidized and cured using anhydrides with the aid of organocatalytic amines, yielding HOSBO-derived RESINs. Both thermal and mechanical properties of RESINs were dictated by the main-chain structures. The curing formulations and conditions were tested extensively to obtain the optimal mechanical properties of thermosetting resins, ranging from plastic to elastomeric properties. Both polyesters and RESINs were fully degradable under basic conditions.

Facially amphiphilic polyionene biocidal polymers derived from lithocholic acid

Bacterial infections have become a global issue that requires urgent attention, particularly regarding to emergence of multidrug resistant bacteria. We developed quaternary amine-containing antimicrobial poly(bile acid)s that contain a hydrophobic core of lithocholic acid in the main-chain. Interestingly, by choosing appropriate monomers, these cationic polymers can form core-shell micelles. These polymers exhibited biocidal activity against both Gram-positive and Gram-negative bacterial species. It is demonstrated that the micelles can deliver hydrophobic antibiotics that functionally have dual antimicrobial activities. Cytotoxicity assays against HeLa cells showed dosage-dependent toxicity for polymers with longer linkers.

Photoresponsive Supramolecular Polymers Based on Quadruple Hydrogen-Bonding and a Photochromic Azobenzene Motif

A photoresponsive quadruple hydrogen-bonded supramolecular polymer was constructed using photochromic azobenzene and ureidopyrimidinone motifs. The E-isomer of azobenzene preferred to form linear supramolecular polymers and further aggregate as its concentration increased. After irradiation with UV light, the E-isomer was converted into the Z-isomer, and the Z-isomer could also self-assemble into supramolecular polymers with a relatively low degree of polymerization. Moreover, supramolecular polymer films were fabricated by a solution casting process. These supramolecular polymers showed highly reversible trans/cis photoisomerization in both solutions and films under alternating UV and visible light irradiation.