Haibing Wei

Constructing pendent imidazolium-based poly(phenylene oxide)s for anion exchange membranes using a click reaction

A series of poly(phenylene oxide)s (PPOs) bearing a flexible pendent imidazolium cation were prepared by an azide–alkyne cycloaddition between azidomethylated PPO and a novel alkyne-containing imidazolium, and their structures were confirmed by 1H NMR, 13C NMR, and FT-IR. The corresponding anion exchange membranes (AEMs) showed distinct hydrophobic/hydrophilic phase-separated morphology at higher imidazolium content, as evidenced by AFM and SAXS techniques, which favors for the construction of interconnected hydroxide transport channels. As a result, the as-prepared AEMs exhibited higher conductivity (95 mS cm−1, 80 °C, 100% RH) than conventional imidazolium benzylic-type AEM (55 mS cm−1, 80 °C, 100% RH) with even lower IEC. Furthermore, the introduction of a 1,2,3-triazole moiety into the polymer side chain does not compromise its thermal and alkaline stability. This investigation demonstrated that the “click chemistry” strategy will benefit further tailoring of high performance AEMs with “side-chain-type” architectures.

A well-defined biodegradable 1,2,3-triazolium-functionalized PEG- b -PCL block copolymer: facile synthesis and its compatibilization for PLA/PCL blends

A novel biodegradable 1,2,3-triazolium-functionalized PEG-b-PCL copolymer (TAPEC) was synthesized by the “click” coupling of methoxypolyethylene glycol azide and α-propargyl-ω-hydroxyl-poly(ε-caprolactone), followed by the quaternization of the 1,2,3-triazole moiety with iodomethane. All the intermediates and TAPEC were characterized by 1H NMR, FT-IR, and gel permeation chromatography (GPC). Taking advantage of the characteristics of ionic liquid and block copolymer, this ion-containing diblock copolymer is expected to be used as a novel compatibilizer in mixed biopolyester for regulating the interface and crystallization behaviors. Hence, the TAPEC was evaluated as a compatibilizer and an interface emulsifier in the blends of polylactic acid (PLA) and poly(ε-caprolactone) (PCL). Non-isothermal crystallization experimental results showed that the TAPEC with the higher amount of ε-caprolactone units induces a plasticization and nucleate effect that increased the crystallization ability of the PLA phase; meanwhile, in the PCL phase, the agminated ionic cluster acting as a nucleating agent significantly increased the crystalline of PCL.

Tailoring elastomeric properties of waterborne polyurethane by incorporation of polymethyl methacrylate with nanostructural heterogeneity

Although modification of waterborne polyurethane (WPU) using acrylic polymer (PA) is a widespread approach to prepare PU materials with high performance, not much attention has been paid to the variation of elastomeric property of the obtained WPUA hybrid materials with the presence of PA component. In this work, a series of aliphatic polycarbonate (PCDL) based waterborne polyurethane and polymethyl methacrylate (PMMA) hybrid dispersions (WPUA) were fabricated via a two-step procedure. The heterogeneous structure of hybrid dispersions was investigated, showing that the dispersed particles possess a nano-sized core–shell morphology. The hydrogen-bond interactions in hard domains are weakened by incorporation of PMMA component. The nanostructural heterogeneity in the dried films was determined by using MDSC, AFM, SAXS, DMA and linear rheology techniques. The tensile strength and strain-hardening modulus increase and the elongation at break decreases with increasing PMMA content. Plastic deformation of PMMA domains in WPUA only results in a loss in recoverable elasticity at low strains. With an optimized content of PMMA, the WPUA2 sample shows sharp yielding behavior while maintaining high extensibility and good recoverable elasticity at large strains. The improvement in elastomeric properties and other physical properties by incorporating PMMA component can expand the applications of waterborne PUs as environment-friendly thermoplastic elastomers.

Paper-based readout to improve the measuring accuracy of gold nanoparticle aggregation-based colorimetric biosensors

The dynamic process of nanoparticle aggregation, especially the salt-induced aggregation that has a high aggregation rate in 300 seconds, is an obstacle to accurate signal capture in a predetermined time and well-repeatable result acquisition for biosensing purposes. In this study, chromatography paper was used to inhibit the aggregating process of gold nanoparticles (AuNPs) in a label-free ssDNA and unmodified AuNP system. To verify the inhibition ability of the chromatography paper towards AuNP aggregation, the aggregation behavior of AuNPs in solution state and on the chromatography paper was studied through monitoring the surface plasmon resonance (SPR) absorbance of 13 nm AuNPs at 520 and 650 nm (A650/A520). To avoid the effect of environmental light during data acquisition, a UV-vis diffuse reflectance spectrometer was employed for paper samples instead of a smartphone as a signal recorder. Then, the paper-based biosensor was applied to our pH alarm system and the biosensing of ochratoxin A, and the results showed that the paper-based assay provided accurate sensing results with stable signals as compared to the solution assay.