Nylon 6 can be degraded using hydrochloric acid to produce a “pseudo” amino acid ionic liquid ε-aminocaproic acid hydrochloride. This degradation process has the advantages of operational simplicity and mild reaction conditions as well as avoiding energy-consuming and tedious purification process. The produced “pseudo” amino acid ionic liquid shows good solubility for chitosan due to its unique structure, proving it is promising as a functional material. This process to produce ionic liquids is innovative, which can help to solve the serious environmental problems caused by the waste nylon 6. It opens a new way for waste polymers utilization.

Imidazolium acetate ionic liquids show high efficiency in the degradation of polylactides (PLA): degradation degree of PLA can reach almost 100 % in imidazolium acetate ionic liquids at 170°C and 1 h under atmospheric pressure, while the degradation degree of PLA remains close to 0 % using neutral 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4) and acidic ionic liquids at the same reaction conditions. With the increase of both the amount of acetate ionic liquid and the reaction temperature, the degradation degree of PLA increases. The structure of ionic liquids affects the degradation behavior of PLA: for cations, the proton from the C-2 position on the imidazolium ring is involved in the degradation of PLA; the degradation of PLA increases with the increase of the alkyl side-chain length of imidazolium cations; for anions, moderate basicity of the acetate ion contributes to the high activity of the imidazolium acetate ionic liquids in the degradation of PLA.

Highly efficient dechlorination of PVC has been realized at 180 °C and at atmospheric pressure, using 1-butyl-3-methylimidazoliumhydroxide ([Bmim]OH) as an environment-friendly reaction medium: in the absence of an external base or solvent the dechlorination efficiency is as high as 91.2%, while it is only 38.1% for PVC without ionic liquids. The dechlorination process follows first-order kinetics with apparent activation energy of 44 kJ mol−1. Mechanistic analysis provides evidence for the equilibrium presence of carbene species, together with the hydroxide ions in [Bmim]OH, thus enhancing the dechlorination of PVC via a combined elimination and substitution mechanism.

Highly efficient recycling of methyl tetrahydrophthalic anhydride-cured epoxy resin is feasible using a poly(ethylene glycol) (PEG)/NaOH catalytic system, which can completely solubilise the epoxy resin at 180 °C in 50 min under atmospheric pressure. The structure of the solvolysis products has been characterized by FTIR, 1H NMR, 13C NMR, GPC and ESI-MS, indicating the decomposition of the curing bond through ester hydrolysis accompanied by transetherification as the plausible solvolysis mechanism. The process possesses high decomposition efficiency without requiring additional organic solvents or pressure, stressing the potential of this method for recycling of other anhydride-cured thermosetting resins.

Thermal degradation of ABS and denitrogenated ABS samples (DABS), prepared by sequential hydrolysis of ABS using PEG/NaOH, has been investigated under inert gas and at atmospheric pressure in a temperature range between 40 and 700 °C, by means of TGA, TGA-IR, and TGA-MS, to study the link between original structure of DABS and eventual pyrolysis. For DABS, thermal decomposition begins at the side groups of –CONH2 and/or –COOH, resulting in a lower initial degradation temperature of DABS (around 330 °C) relative to ABS (372.5 °C). Moreover, less HCN and acrylonitrile evolve from the DABS samples, while the evolution of CO2 starts earlier and becomes more important, in line with the decreased number of –CN groups and the increased number of –COOH functional groups due to hydrolysis. The results from thermo-analytical experiments were confirmed by batch pyrolysis tests: the nitrogen content of oil produced from DABS pyrolysis is much lower, compared with that from ABS, proving that effective denitrogenation of ABS prior to pyrolysis is beneficial to the quality of pyrolysis oil.

Alkaline hydrolysis of acrylonitrile–butadiene–styrene (ABS) copolymers has been systematically investigated to demonstrate the use of reaction systems based on polyethylene glycol (PEG)/hydroxides for N-elimination from ABS. The structure of denitrogenated ABS has been characterized using elemental analysis, FTIR, 1H-NMR, and solid state 13C CP-MAS NMR, indicating sequential hydrolysis as a plausible mechanism of elimination of N from ABS. The effects of reaction conditions such as solvent selection, reaction temperature, alkaline species and concentration, as well as PEG molecular weight were evaluated. At optimal conditions (THF, PEG600, 4.3 wt % of NaOH), as much as 93.1% of the original nitrogen content of ABS was removed in 2 h at 160 °C, while it is only 35.6% without PEG. This clearly demonstrates the high-efficiency of a PEG/hydroxides catalytic system for denitrogenation of ABS, stressing the potential of this method for denitrogenation of other N-containing polymers.

A catalytic system based on Na2WO4/CH3COOH/H2O2 effectively oxidizes natural rubber (NR) to prepare telechelic epoxidised liquid natural rubber (TELNR). The Na2WO4/CH3COOH/H2O2 catalytic system possesses a much higher epoxidation efficiency than the traditional CH3COOH/H2O2 system: the epoxidation degree (Xepoxy) of products increases from merely 5.6% (CH3COOH/H2O2) to values as high as 52.1% (Na2WO4/CH3COOH/H2O2) by reacting for 24 h at 60 °C. Moreover, this catalytic system also induces hydrolytic degradation so that the weight average molecular weight (Mw¯) of NR decreases, e.g., from 14.10 × 105 Da (NR) to 0.57 × 105 Da (TELNR) after reacting for 30 h.The catalytic process probably proceeds via a mononuclear tungsten peroxo-species with coordinated peracetyl/acetyl group, as suggested by ESI-MS measurements. During oxidation, the tungstic anion [W(CH3COOO)(O)(O2)2]− not only catalyzes NR epoxidation, but also induces a further oxidation of epoxy groups to form ketones and aldehydes.

Nanoporous cellulose foams have been successfully prepared by a procedure in three steps: (i) dissolving in a room temperature ionic liquid (1-butyl-3-methylimidazolium chloride); (ii) coagulation in water; (iii) rapid freeze drying using liquid N2. The results show that the foam had a 3D open fibrillar network structure with the specific surface area as high as 186.0 m2/g and a porosity of 99%. Moreover, the cellulose foam shows cellulose II crystalline structure. Cellulose concentration in hydrogel as well as drying methods influences upon the structure and pore size of cellulose foams.