Six new coordination compounds Ni(cppca)(H2O)4·2H2O (1), Co(cppca)(H2O)4·2H2O (2), {Cd2(cppca)2(H2O)5}n (3), {[Cd3(cppca)2(H2P2O7)(H2O)6]·2H2O}n (4), {Cu(Hcppca)2}n (5) and {[Mn7(cppca)6(Hcppca)2(H2O)10]·2H2O}n (6) have been obtained by reactions of the corresponding metal salts and the rigid ligand 5-(3-carboxy-phenyl)-pyridine-2-carboxylic acid (H2cppca) under solvothermal conditions. All the compounds were fully characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, thermal analysis and powder X-ray diffraction. The single-crystal X-ray analyses showed that compounds 1–6 have rich structural chemistry ranging from mononuclear (1 and 2), one-dimensional (3 and 4), two-dimensional (5) to three-dimensional (6) structures. Moreover, the framework of compound 6 may be simplified into a 3-nodal net with Schlafli symbol {42·6}{42·82·102}{43·62·8·104}2, which shows an unprecedented (3,4,5)-connected topology net. The fluorescent properties of compounds 3 and 4 were investigated in the solid state and in various solvent emulsions, which indicated that compounds 3 and 4 are both highly sensitive fluorescent probes for the acetone molecules. Variable-temperature magnetic susceptibility measurements indicate weak antiferromagnetic interactions between metal centers in compounds 1, 2, 5 and 6.

•Thermolysis of carbon fibre reinforced epoxy resin in nitrogen–oxygen atmosphere.•Temperature, oxygen concentration and reaction time are important factors.•About 80% of tensile strength and modulus was preserved at optimum conditions.Pyrolysis is a common method for recycling carbon fibre reinforced polymer composites. However, carbonized residue is preferred to form on fibre surface. Thermal processing in air could eliminate the carbonized residue but the mechanical strength of the inherent fibre tends to be damaged by oxidation. Here, we investigated the influence of the temperature, oxygen concentration in nitrogen and time on the thermal decomposition of carbon fibre reinforced 4,4′-diaminodiphenylmethane cured epoxy resin composite and properties of the recycled carbon fibres. The properties of the recycled carbon fibre were characterized using single tensile test, SEM and XPS. Temperature, oxygen concentration and reaction time appear to be the important factors to tensile strength of the recovered carbon fibres. About 80% of tensile strength and modulus was preserved at optimum conditions. Gas and liquid products from DDM cured epoxy resin were also analysed in nitrogen and 5% O2–95% N2.

Recycling of carbon fiber reinforced epoxy resin composites has been investigated using molten potassium hydroxide as reaction media. The epoxy resin in composites was decomposed at temperatures ranged from 285 to 330 °C. The recovered carbon fibers were characterized by SEM, XPS and single fiber tensile test. More than 95% of the tensile strength of the virgin carbon fibers was retained. The surface C–OH decreased and COOH increased with increasing temperature. The decomposition products of epoxy resin in KOH was separated and analyzed by FTIR and MALDI-TOF. A possible mechanism for the decomposition of epoxy resin is proposed. The real-world CFRP wastes containing various contaminants such as thermoplastics, paints, sealants and glass fibers were also decomposed in the molten KOH.

Conversion of waste polymer on a metal-free catalyst is a promising method for the preparation of nanocarbons. Herein, we synthesized porous carbon sheets and hollow carbon shells through the carbonization of polystyrene on magnesium oxide with different morphologies at 700 °C using a one-pot method. The morphologies, microstructure, phase structure, surface element composition, thermal stability, and textural properties of the obtained nanocarbons were analyzed by SEM, TEM, XRD, TGA, and Raman. The yield of the nanocarbons increased as the weight ratio of magnesium oxide to polystyrene increased. Magnesium oxide acted as a template for the shape-controlled growth of the carbon nanostructure. The surface area of the porous carbon sheets and hollow carbon shells reached 854 and 523 m2 g−1 without any activation, respectively. The porous carbon sheets were used as adsorbents to remove methylene blue from water and showed an adsorption capacity of 358.8 mg g−1. Product composition for the pyrolysis of polystyrene in the presence of magnesium oxide was analyzed using GC and GC-MS to elucidate the reaction mechanism. The yield of styrene in the liquid products reached 50% by the catalysis of polygonal magnesium oxide. This strategy provides a cheap and sustainable catalyst for converting polymer into high-value nanocarbons and useful chemicals.

Two series of 3–12 multiarm star polymers of butadiene and styrene (S-PB and S-PS) with high Mn of arms (≥20 kg mol−1) and narrow PDI (≤1.04) were synthesized via click chemistry between azide-terminated polymers and multialkynyl organic molecules. Comparing to the previous report, higher yield of coupling reaction (≥85%) was obtained along with increasing arm number and molecular weight of the single-arm polymer (over 4–5 times that before). In particular, 96.1%, as the highest efficiency, occurred in the synthesis of 12-arm star PB. The 4-miktoarm star copolymer of butadiene and styrene was also synthesized with high yield (95.1%), high arm Mn and narrow PDI (1.04) by one pot synthesis using click reaction between two different linear polymers (PS-N3 and PB-N3) and a 4-arm core. All the star polymers were characterized by GPC-MALLS-Viscosity-DRI. These multiarm star polymers exhibit morphologies from random coil to hard sphere depending on the arm-number of the star polymers. Intrinsic viscosity appeared the maximum with increasing arm numbers in star PB and PS, in which PB-4arm and PS-6arm had the highest values, respectively.

Recently, upcycling waste plastics into high-value-added carbon nanomaterials has attracted much attention; however, few studies have focused on the conversion of waste plastics into graphene with high yield. Herein, we report a simple novel method to synthesize graphene flakes (GFs) with high yield through catalytic carbonization of waste polypropylene (PP) using organically modified montmorillonite (OMMT) as degradation catalyst and template at 700 °C. The yield, morphology, microstructure, phase structure, thermal stability, and surface element composition of GFs were investigated. In addition, it was found that OMMT not only promoted the degradation of waste PP into light hydrocarbons and aromatics but also acted as template and catalyzed carbonization of the light hydrocarbons and aromatics into GFs. At last, a possible mechanism for the formation of GFs was put forward. This simple approach provides a novel way to effectively prepare high-value-added GFs using waste plastics as carbon sources.

A novel combined catalyst of activated carbon (AC) with Ni2O3 was demonstrated to be much more efficient than AC or Ni2O3 alone in enhancing the char yield of polypropylene (PP) and improving its char layer structure, which greatly improved the thermal stability and flame retardancy of PP. The results of X-ray diffraction, field-emission scanning electron microscope and transmission electron microscope revealed that the residual char mainly consisted of carbon nanotubes (CNTs). Thermal gravimetric analyses results indicated that the combination of AC and Ni2O3 dramatically enhanced the thermal stability of PP. The flame retardancy of PP and its composites was studied by cone calorimeter test. The heat release rate and total heat release of the ternary PP/7.5AC–7.5Ni2O3 composite decreased significantly in comparison with those of neat PP. The investigation of the synergetic mechanism showed that in the presence of both AC and Ni2O3, a large amount of CNTs were in situ formed from the degradation products of PP during combustion. This not only reduced the release of flammable degradation products of PP, but also acted as a thermal shield for energy feedback from the flame. In addition, the formation of a network-like structure of AC and Ni2O3 particles in PP matrix favored the formation of a more compacted protective layer, which enhanced the flame retardancy of PP.

Recently, there has been intense interest in the conversion of plastics into high value-added carbon nanomaterials (CNMs), however, the effect of catalyst diameter on the formation of CNMs is still ambiguous. Herein, uniform NiO catalysts with different diameter (18–227 nm) were firstly prepared by a sol–gel combustion synthesis method and calcination at different temperatures. Subsequently, the combined organically-modified montmorillonite (OMMT)/NiO catalyst was used to catalyze carbonization of polypropylene (PP, selected as an example of plastics) into CNMs at 700 °C. The effect of NiO catalyst diameter on the yield, morphology, microstructure, phase structure, thermal stability and texture properties of CNMs including sponge-like cup-stacked carbon nanotubes (CS-CNTs) and carbon fibers were investigated by scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, X-ray diffraction, Raman spectroscopy, thermal gravimetric analysis and N2 sorption. Besides, the effects of NiO catalyst diameter on the coalescence and reconstruction of NiO particles were explored. It was demonstrated that NiO catalysts with small diameter were more susceptible to coalescence and reconstruction into rhombic shape, which facilitated the growth of long, straight CS-CNTs. Finally, the obtained sponge-like CS-CNTs were found to show high performance in the adsorption of diesel, vegetable oil, kerosene and mineral oil with good recycling performance. It is believed that this work will contribute to the conversion of waste plastics into high value-added CNMs.