Jianyong Jin

Evaluation of gallic acid loaded zein sub-micron electrospun fibre mats as novel active packaging materials

The applicability of gallic acid loaded zein (Ze-GA) electrospun fibre mats towards potential active food packaging material was evaluated. The surface chemistry of the electrospun fibre mats was determined using X-ray photon spectroscopy (XPS). The electrospun fibre mats showed low water activity and whitish colour. Thermogravimetric analysis (TGA) and Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy revealed the stability of the fibre mats over time. The Ze-GA fibre mats displayed similar rapid release profiles, with Ze-GA 20% exhibiting the fastest release rate in water as compared to the others. Gallic acid diffuses from the electrospun fibres in a Fickian diffusion manner and the data obtained exhibited a better fit to Higuchi model. L929 fibroblast cells were cultured on the electrospun fibres to demonstrate the absence of cytotoxicity. Overall, the Ze-GA fibre mats demonstrated antibacterial activity and properties consistent with those considered desirable for active packaging material in the food industry.

Optical properties of perfluorocyclobutyl polymers. III. Spectroscopic characterization of rare-earth-doped perfluorocyclobutyl polymers

We present a continuation of two previous studies [J. Opt. Soc. Am. B20, 1838 (2003) and J. Opt. Soc. Am. B21, 958 (2004)] on the optical characteristics of perfluorocyclobutyl-based polymers. Previously, the spectral dependences of the refractive index and the extinction coefficient have been calculated, and investigations were made into the theoretical and measured attenuation spectra of these polymers. Here, we report on the erbium-doped perfluorocyclobutyl aryl ether polymer 1,1,1-tris(4-trifluorovinyloxy)phenyl ethane. The absorption and fluorescence spectra are provided, including the Judd-Ofelt parameterization. The Judd-Ofelt parameters are found to be Omega_2 = 16.05×10^-20 cm², Omega_4 = 3.67×10^-20 cm², and Omega_6 = 3.59×10^-20 cm². These results are compared with those for a similar study on erbium-doped poly(methyl methacrylate), and conclusions are drawn concerning the effect of host properties in the 1550 nm region.

Effect of Mesoscopic Fillers on the Polymerization Induced Viscoelastic Phase Separation at Near- and Off-Critical Compositions

We have investigated the effect of mesoscopic fillers on the polymerization induced viscoelastic phase separation of thermoplastic modified thermosets at near- and off-critical concentrations using optical microscopy, time-resolved light scattering, dynamic mechanical analyses, and rheological instrument. Mesoscopic fillers including sepiolite and nanosized silica showed a significant enhancement effect in viscoelastic phase separation, and resulted in pronounced differences in the phase structures at all concentrations of polyetherimide modified epoxy resins with dynamic asymmetry. For blends near critical concentration, the introduction of fillers led to much finer phase structure with smaller characteristic length scale. At off-critical composition (i.e., blends with low concentration of slow dynamic component), the strong polymer chain entanglement resulted in enwrapped mesoscopic fillers within a slow dynamic phase. The rheological behavior of the blends clearly demonstrated the significant enhancement effect of mesoscopic fillers in the viscoelastic phase separation. The apparent activation energy of polymer chain mobility obtained from dynamic mechanical study of glass transition reflected strong wrapping behavior of polymer chains on mesoscopic fillers, which were consistent with the rheological and light scattering study.

Synthesis of perfectly alternating copolymers for polymers of intrinsic microporosity

Copolymers properties are controlled not only by co-monomers’ composition but also their sequence distribution along the chain. We hereby report a strategy to the synthesis of perfectly alternating PIMs copolymer, an important class of material for gas separation membrane. We achieve this copolymer microstructure through two-pot synthesis process via ABA trimer intermediate. For comparison, both alternating and statistical copolymers with same composition were prepared and characterized with 1H and 13C NMR, FT-IR, MALDI-ToF, GPC, TGA, DSC and WAXD. The present work offers new method for repeating unit sequence control in step growth polymerization system.

Influence of Heat Curing on Structure and Physicochemical Properties of Phenolic Acid Loaded Proteinaceous Electrospun Fibers

Effects of heat treatment on structure and physicochemical properties of zein (Ze) and gallic acid loaded zein (Ze-GA) electrospun fiber mats were investigated. The electrospun fiber mats displayed different surface and physicochemical properties after being heat-cured at 150 °C for 24 h, which were closely related to the initial amount of loaded gallic acid. The gallic acid was released from the Ze-GA fiber mats in a constant manner, but heat curing decreased the rate of release. Heat curing remarkably increased the molecular weight of the Ze and Ze-GA electrospun fiber mats. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis of the fiber mats indicated variations in zein protein secondary structure after heat curing. (13)C solid state NMR (SS-NMR) confirmed the presence of a different chemical environment among the fiber mats. The fabrication of heat-cured zein based electrospun fibers in this study may find applications in the food packaging industry.

The synthesis and lectin-binding properties of novel mannose-functionalised polymers

We have utilised the CuAAC “click” reaction to introduce α-D-mannose functionality via a pre-polymerisation modification in order to synthesise novel water soluble, mannose-functionalised HEMA copolymers. The ability of these copolymers to bind to the mannose selective lectin Concanavalin A (Con A) has been investigated and has shown that copolymers containing a higher percentage of mannose functionalised monomer 7 could quantitatively precipitate Con A more efficiently than polymers that contained a lower percentage of mannose. Encouraged by these positive binding results, we successfully synthesised a series of novel glycohydrogels, based on the structure of the copolymers 8a–8e, which contain varying amounts of mannose. These hydrogels can potentially be developed into biocompatible biomaterials that have the ability to bind to mannose receptors.

Synthesis of Novel Triazole-Containing Phosphonate Polymers

The objective of this research was to develop novel phosphonate-containing polymers as they remain a relatively under researched area of polymer chemistry. Herein, we report the synthesis and characterization of 2-(1-(2-(diethoxyphosphoryl)ethyl)-1H-1,2,3-triazol-4-yl)ethyl acrylate (M1) and diethyl (2-(4-(2-acrylamidoethyl)-1H-1,2,3-triazol-1-yl)ethyl)phosphonate (M2) monomers using the copper-catalyzed azide–alkyne cycloaddition (CuAAC) ‘click’ reaction, and their subsequent polymerization via both uncontrolled and reversible addition–fragmentation chain transfer (RAFT) polymerization techniques yielding phosphonate polymers (P1–P4).

Synthesis of a Novel Polyaniline Glycopolymer and its Lectin Binding Studies

We report the multistep synthesis and polymerisation of a novel aniline derivative with a pendant α-d-mannose substituent. The α-D-mannose functionality was successfully introduced before polymerisation via copper-catalysed azide alkyne click chemistry and the resulting monomer was polymerised using general oxidative polymerisation conditions, producing a water soluble mannosylated polyaniline. The polymer was characterised by several techniques and compared with standard polyaniline. The selective binding of the polymer to Concanavalin A (ConA) was successfully demonstrated by the precipitation of polymer–ConA aggregates. Potential applications of these novel polyaniline glycopolymers could include the development of electroactive biomaterials with the ability to bind mannose receptors, or as sensors for proteins or microbes.

A new high-capacity metal ion-complexing gel containing cyclen ligands

We describe a new polymeric hydrogel that binds divalent metal ions with large binding constants and capacity. A new acrylate monomer with the pendant cyclen, tri-tert-butyl-10-(2-(2-(2-(methacryloyloxy)ethoxy)ethoxy)-2-oxoethyl)-1,4,7,10-tetraazacyclododecane-1,4,7-tricarboxylate, was polymerised by RAFT to a roughly spherical 5–9 unit oligomer bearing a carboxylate-functionalised end-group. This was de-protected and coupled to an amine dendrimer then crosslinked into a nylon-type hydrogel capable of absorbing more than 10 wt% copper ions.

Photoinitiators for two-photon polymerisation: effect of branching and viscosity on polymerisation thresholds

A series of multi-branched two-photon photoinitiators (PIs) based around the well-known triphenylamine donor core were synthesised for use in two-photon polymerisation (TPP) and are designated as compounds 6, 7 and 8. The use of a phenylene-vinylene π-system was used with an ethyl ester acceptor moiety which gives dipolar (6), quadrupolar (7) and octupolar (8) branching. Two-photon absorption cross-sections (δ2PA) of 126 GM, 358 GM and 590 GM were measured at 780 nm for 6, 7 and 8, respectively. The fluorescence quantum yields (ϕF) were determined in both MeOH and the acrylate system employed for TPP, and demonstrate the impact of viscosity upon photophysical properties of multi-branched molecules. Excellent polymerisation thresholds were demonstrated in the μW region: namely 45 μW (6), 61 μW (7) and 27 μW (8) at a writing speed of 50 μm s−1. Finally, an explanation for the disparity of polymerisation thresholds is proposed for these PIs and provides insight into the future development of low threshold PIs for TPP.