Preparation and characterization of non-isocyanate polyurethane hydrogels and coatings for indoor air decontamination

Indoor air pollution was recently highlighted to be responsible for many health problems like respiratory track irritation. Organic solvents and some plasticizers are taking part to this problem and belong to the family of volatile organic compounds (VOC) that accumulate inside our more and more “hermetically” closed living spaces. Amongst them, toxic formaldehyde (FA) is largely used for formulating furniture coatings, carpets, flooring and is one of the main contributors of our indoor air pollution. Few strategies have been developed for dealing with FA accumulation, notably by capturing in porous matrices or by (photo)degradations using rare earth-based metals or photocatalysts, or by bioremediation using enzymes. However, when this thesis started, bio-active coatings (thus loaded by FA degrading enzymes) able to efficiency capture and degrade FA into non-toxic compounds and that could be easily deposited on elements of our closed areas (walls, ceiling, furniture, etc.) were not reported. This thesis aims to prepare new organic coatings able to reduce formaldehyde by degradation by
enzymes under ambient conditions, thus adaptable for indoor life space implementation, using a chemistry that is as green as possible. As enzymes are often inactivated when used out of their natural environment, this work is mainly focused on developing new routes for producing coatings from precursors and under conditions that are tolerant to the enzyme stability and activity. Non-isocyanate polyurethanes of the poly(hydroxyurethane)-type are investigated in this work, as they constitute greener alternatives to the widespread conventional polyurethanes found in many high performance coatings. Indeed, these conventional polyurethanes, produced by the toxic isocyanate chemistry, are sources of pollution due to the presence of residual solvents or residual isocyanates that are released in the environment. Therefore, this work is dedicated to the elaboration of greener poly(hydroxyurethane)s adaptable for enzyme entrapment by the polyaddition of poly(cyclic carbonate)s to polyamines with the challenge to produce them in water at room temperature without requiring the use of organic solvents. The influence of the structure of the comonomers and the reaction conditions on the formation of the polymer matrix and the entrapment of the formaldehyde degrading enzyme is explored and largely discussed. The potential of the various products as coatings for formaldehyde abatement are also reported. This thesis was carried out in the frame of the BIODEC project that was financed by le Fonds européen de développement régional “(FEDER) et la Wallonie dans le cadre du programme opérationnel ‘Wallonie-2020.EU’”.