Qianli Rick Chu

Linear polyester synthesized from furfural-based monomer by photoreaction in sunlight

A novel linear polyester was synthesized from furfural-based monomer through solvent-free polymerization using sunlight. Furfural was first converted to 2-furanacrylic acid as a key photoreactive building block. The desired monomer was then prepared by linking two 2-furanacrylic acid molecules with 1,5-pentanediol, which can also be produced from furfural. An important photoreactive crystalline assembly of the monomer was characterized by powder and single crystal X-ray diffraction. The new linear polyester that contains 100% components from biomass-derived chemicals was synthesized by sunlight photoreaction of the pre-organized monomer in the solid state in 24 hours. The solvent-free sunlight photoreaction process was monitored by FT-IR and a key intermediate was confirmed by single crystal X-ray diffraction. Nanofiber of the linear polyester was observed under TEM. Similar to polyethylene terephthalate (PET) used in beverage bottles, the novel polyester contains alternating rigid and flexible moieties in the polymer chain.

An unsaturated hydrogen bonded network generated from three-fold symmetric carbamates

A new hydrogen bonded network self-assembles under mild conditions from benzene-1,3,5-triyl tris(butyl carbamate) or benzene-1,3,5-triyl tris(hexyl carbamate). One of the carbonyl groups in the tri-carbamate does not form a CO⋯H–N hydrogen bond in the sheet-like structure. Although the building blocks only differ in the carbon numbers of the side chains, this 2D unsaturated hydrogen bonded network is different from the saturated one self-assembled from benzene-1,3,5-triyl tris(propyl carbamate). The lamellar structures were studied and compared by using their melting points, NMR and FT-IR spectroscopy, and single crystal X-ray diffraction.

Polyladderane Constructed from a Gemini Monomer through Photoreaction

Polyladderane, the first polymer to contain the ladderane functional group, was synthesized from a gemini monomer through photoreaction in the solid state. The modular design of the gemini monomers used to create polyladderane allowed specific structural modification, resulting in the formation of two distinct polymer products. Monomers were synthesized by connecting two photoreactive units, either sorbic acids (monomer I) or 2-furanacrylic acids (monomer II), with a 1,4-butanediol linker. Single-crystal X-ray diffraction analysis of the monomers confirmed that they packed in the desired head-to-tail orientation and within a viable distance for photoreaction by electronically complementary interaction. Pre-organized gemini monomers were irradiated with UV light and monitored by FT-IR. Two polyladderanes with cis,anti,cis-[3]-ladderane as a characteristic functional group were constructed stereospecifically in 24-36 hours.

Cyclobutane-1,3-Diacid (CBDA): A Semi-Rigid Building Block Prepared by [2+2] Photocyclization for Polymeric Materials

A previously overlooked building block, cyclobutane-1,3-diacid (CBDA), is introduced to materials synthesis due to its great potentials. As an example of CBDA, α-truxillic acid or 2,4-diphenylcyclobutane-1,3-dicarboxylic acid, was readily synthesized from commercially available trans-cinnamic acid. This CBDA showed outstanding stability both in sunlight and upon heating. While its two carboxylic acid groups can be readily utilized in connecting with other molecules to form new materials, the cyclobutane ring was able to tolerate acid and base treatments showing good chemical stability. A series of cyclobutane-containing polymers (CBPs), namely poly-α-truxillates, were obtained by condensation between α-truxillic acid and diols including ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-petanediol, and 1,6-hexanediol. The structures of these poly-α-truxillates were analyzed by NMR, FT-IR, and HRMS. Powder X-ray diffraction results of the poly-α-truxillates indicated that they are semi-crystalline materials. Preliminary thermal, chemical, and photochemical tests showed that the poly-α-truxillates exhibited comparable stabilities to PET.