Continuous flow mechanochemical and melt-phase synthesis at kg h ⁻¹ rates from solid reagents and either no solvent, or only minimal solvent, is reported.

The concerns about the accumulating plastic waste pollution have stimulated the rapid development of bioplastics, in particular biodegradable bioplastics derived from renewable resources. Driven by a low carbon circular economy, bioplastics production is estimated to reach a 40% share of the plastics market by 2030 (Bioplastics Market Data, 2018). It is expected to substitute petrochemical-based plastics in many applications, from food packaging, pharmaceuticals, electronics, agriculture to textiles. The current biodegradable bioplastics have met challenges in competing with engineering polymers such as PET and Nylon in terms of processing capacity at the industry scale, mechanical robustness, thermal resistance, and stability. Poly(glycolic acid) (PGA) has a similar chemical structure to PLA but without the methyl side group, which allows the polymer chains to pack together tightly and results in a high degree of crystallinity (45–55%), high thermal stability (T_m = 220–230 °C), exceptionally high gas barrier (3 times higher than EVOH), as well as high mechanical strength (115 MPa) and stiffness (7 GPa). Meanwhile, PGA is rapidly biodegradable and 100% compostable, showing a similar biodegradation profile to cellulose. To date, PGA has been mainly used in the form of copolymers, such as poly(lactic-co-glycolic acid) (PLGA). Its unique properties have often been overlooked and are yet to be explored. This is caused by its intrinsic characteristics such as high hydrophilicity, rapid degradation, insolubility in most organic solvents and brittleness that have hindered its practical applications. Here we introduced the synthetic chemistry, processing methods, modification, and applications of PGA, aiming to provide a critical discussion about the technical challenges, development opportunities, and solutions for PGA-based materials. The future direction and perspectives for high-performance PGA are proposed. Given its synthesis diversity and unique properties, PGA shows great potential to substitute engineering petrochemical-based polymers for high temperature and high gas barrier packaging applications.

2D Boron Nitride Nano-sheets (BNNS) were prepared using a high-pressure homogenisation process to exfoliate bulk hexagonal boron nitride (h-BN). The effectiveness of this process was studied by characterising bulk h-BN and BNNS post-processing using numerous techniques. The BNNS produced was composed of a mixture of sheets having lengths on the nanometre (nm) scale, but lateral thicknesses on the micron (μm) length scale. The product was a macro-porous material containing slit-like pores with a surface area of 170 m² g⁻¹. It had a polycrystalline structure with d₀₀₂ = 0.335 nm and L₀₀₂ = 2 nm. From the sharp E_2g peak in the Raman spectrum at 1360 cm⁻¹ (FWHM = 12.5 cm⁻¹), the sheets had a low defect density and were highly exfoliated. X-Ray photoelectron spectroscopy (XPS) studies detected B–OH and N–H groups on the BNNS surface and the presence of residual surfactant. Contact angle measurements (60° ± 3° (0 s); 40° ± 2° (10 s)) confirmed a hydrophilic surface. The BNNS was thermally stable under oxidative conditions up to 323 °C.

The facile silane functionalization of graphene oxide (GO) was achieved yielding vinyltrimethoxysilane-reduced graphene oxide (VTMOS-rGO) nanospheres located in the inter-layer spacing between rGO sheets via an acid–base reaction using aqueous media. The successful grafting of the silane agent with pendant vinyl groups to rGO was confirmed by a combination of Fourier-transform infrared (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The structure and speciation of the silane-graphene network (nanosphere) and, the presence of free vinyl groups was verified from solid-state magic angle spinning (MAS) and solution ¹³C and ²⁹Si nuclear magnetic resonance (NMR) measurements. Evidence from Scanning Electron Microscopy (SEM), High-Resolution Transmission Electron Microscopy (HRTEM) and TEM-High-Angle Annular Dark-Field (TEM-HAADF) imaging showed that these silane networks aided the exfoliation of the rGO layers preventing agglomeration, the interlayer spacing increased by 10 Å. The thermal stability (TGA/DTA) of VTMOS-rGO was significantly improved relative to GO, displaying just one degradation process for the silane network some 300 °C higher than either VTMOS or GO alone. The reduction of GO to VTMOS-rGO induced sp² hybridization and enhanced the electrical conductivity of GO by 10⁵ S m⁻¹.