Polyurethane foams, are highly demanded in many applications and their use is increasing incessantly. Besides these traditional applications, recently polyurethane foams with different morphologies have been used in environmentally-oriented applications as biofilters for waste air and water treatments, microporous sorption materials, carriers of bio-catalyst (enzyme) in biotechnologies and lightweight packing materials with high surface area for cell attachment and biofilm development, etc. For these applications it is important that polyurethane foams are not toxic, bio-based and capable of decomposing in the environment. Therefore, there is a huge potential for conducting research focused on biodegradation of newly developed bio-foams and their ecotoxicological impacts and thus to make valuable contribution in solving environmental and resource depletion problems of the world. This review gives an overview about environmental degradation of polyurethane foams with special accent to their biodegradation behavior and ecotoxicity. The paper is organized as follows: (1) polyurethane foams are shortly introduced together with their current recycling options, (2) innovative approaches in producing of bio-based and biodegradable polyurethane foams are mentioned, (3) possible ways of environmental degradations of polyurethane foams are present, (4) aspects of polyurethane foam biodegradation are discussed in details and finally (5) ecotoxicity of polyurethane foams is also mentioned.

Polycarbonate and polyurethane scraps from end-of-life vehicles were converted into liquid recycled polyols with hydroxyl number around 300 mgKOH·g^–1 by using medium chain glycerides of coconut oil. The obtained polyols were used for preparation of low-density rigid polyurethane foams. It was found that up to 50 wt % of the virgin petrochemical polyol can be replaced by the recycled polyols without any negative effect on the foaming process. The obtained foams exhibited the apparent density of 40–44 kg·m^–3, the homogeneous cellular structure with a high content of closed cells (>91 vol %) and the beneficially low value of lambda coefficient (∼23 mW·m^–1·K^–1). The exceptionally high compressive strength (>350 kPa in parallel to foam rise direction) of the rigid PUR foams with 50 wt % of recycled polyol derived from polycarbonate scrap resulted probably from the unique structure of recycled polyol combining rigid aromatic segments together with flexible coconut oil glyceride units. In conclusion, this approach utilizing the renewable coconut oil-derived reagent provides a sustainable recycling solution for two major plastics from automotive waste.

Bio-based cyclic carbonates are of significant research interest as monomers for non-isocyanate polyurethane (NIPU) synthesis. This research describes the synthesis of a series of five-membered bis(cyclic carbonate)s using bio-based polyether polyols (PO3G) with different molecular weights (250, 650 and 1000 g mol⁻¹) and carbon dioxide as green feedstocks. The utilization of CO₂ as a source of carbon in the chemical reaction is in agreement with the sustainable chemical industry. Furthermore, in order to support the green and sustainable polymer chemistry approach, the syntheses were attempted under solvent-free conditions. The implemented synthetic methods are focused on the design of processes and final products that minimize negative environmental impact. Detailed chemical structure analysis of synthesized products was performed using a combination of spectroscopy techniques (ATR-FTIR as well as 1D and 2D NMR techniques), mass spectrometry (MALDI-TOF MS) and chromatography analysis (SEC). The formation of the main product with two terminal cyclic carbonates was confirmed and the formed side products were also identified, characterized and quantified. Finally, as a proof of concept, the synthesized bis(cyclic carbonate)s were successfully used for the preparation of NIPU thermosets. Chemical and mechanical properties of the produced materials suggest their high potential for future applications, e.g. as sound absorbing materials.

This work presents the cell structure and selected properties of polyurethane (PUR) foams, based on two types of hydroxylated used cooking oil and additionally modified with three different flame retardants. Bio-polyols from municipal waste oil with different chemical structures were obtained by transesterification with triethanolamine (UCO_TEA) and diethylene glycol (UCO_DEG). Next, these bio-polyols were used to prepare open-cell polyurethane foams of very low apparent densities for thermal insulation applications. In order to obtain foams with reduced flammability, the PUR systems were modified with different amounts (10–30 parts per hundred polyol by weight—php) of flame retardants: TCPP (tris(1-chloro-2-propyl)phosphate), TEP (triethyl phosphate), and DMPP (dimethyl propylphosphonate). The flame retardants caused a decrease of the PUR formulations reactivity. The apparent densities of all the foams were comparable in the range 12–15 kg/m³. The lowest coefficients of thermal conductivity were measured for the open-cell PUR foams modified with DMPP. The lowest values of heat release rate were found for the foams based on the UCO_TEA and UCO_DEG bio-polyols that were modified with 30 php of DMPP.