Posted on 07/09/2023 in Electric & Electronic 2023
Computer modelling to propose safer FRs

Hannah Flerlage and Steven Beijer, University of Amsterdam

SSbD (Safe and Sustainable by Design) is applied to redesign P FR for reduced environmental hazard using a computer-based approach, starting from the existing PIN phosphorus flame retardant Tri-iso-butyl phosphate (TiBP). This PIN FR has been identified as a preferable alternative (Hendriks & Westerlink, pinfa Newsletter 56) but is widely detected in the environment, with a half-life in abiotic conditions of a few weeks (van der Schyffel et al., pinfa Newsletter 146). QSAR computer modelling of biodegradability (aerobic, anaerobic), mobility, bioaccumulation and different toxicity endpoints suggest that Tris (2-hydroxyethyl) phosphate (TEHP) could be an environmentally preferable alternative to TiBP and to other FRs such as the halogenated FR Tris(2-chloroethyl) phosphate (TCEP) which is classified as substance of very high concern (SVHC). The phosphate centre of the molecule is unchanged, but the branched alkyl chains are modified to unbranched chains with terminal hydroxy groups. Reduced ecotoxicity of THEP was demonstrated in acute and chronic experimental tests. Further work is now needed to verify the expected degradability of the THEP molecule, to verify whether it is suitable for use as a flame retardant and also to look for synthesis routes which do not involve the chlorinated vector POCl3 and make use of renewable phosphorus from waste.

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