Research Projects

In modern society, polyurethanes-based products tend to add adverse impacts into environment due to non-degradable properties and use of toxic isocyanate reagents and petro-based polyols as precursors in formulation using organic solvents and metal catalysts under rigorous conditions [1]. Indeed, recent development of isocyanate free polyurethanes from sustainable precursors in the form of polyhydroxyurethanes is altered by additional curing step via formation of prepolymers tethered with epoxy or amine functional groups to form hybrid polyhydroxyurethanes, which can show improved molar mass, thermal stability, physicochemical and mechanical properties. The inherent fire safety of such polymeric products is imperative and effort to incorporate flame-retardancy with biodegradability can promote their applications [2]. To achieve these objectives, chosen the renewable sources plant oils, cereal, terpenes and biodegradable polyols to synthesize cyclic carbonate substrates to react with sustainable/commercial diamines along with P-N moiety to afford non-isocyanate polyurethanes (NIPU) with biodegradable and fire-retardant properties to achieve sustainability and safety [3-5]. As such the fire-retardant properties of products as NIPU films/coatings can be attained by functionalization/substitution of reactants tailored with phosphorus and nitrogen or phosphazene etc., essentially as non-halogenated content. NIPU can be obtained by polyaddition reaction of cyclic carbonate (5-, 6- and 8-membered) from substrates with counter reactant containing spacer moiety tethered with amine groups via catalytic-/non-catalytic approach to achieve the sufficient molar mass [6-8]. Such diamines are chosen to be synthesized from the sustainable or commercial precursors, tris(2-aminoethyl)amine, polyoxypropylene diamines, 1,6-hexamethylenediamine etc. [9]. These diamines are crucial to replace the toxic isocyanate and can exhibit sustainable and degradation properties. Altogether, biodegradable/sustainable polyols as well as sustainable/ commercial amines can be chosen with respect to occupational safety and eco-friendly. These hybrid NIPU can be formulated via substitution of cyclic/acylic phosphorus(V) precursors as substituent for incorporation of fire retardant properties as compared to neat NIPU [10].To achieve the mechanical strength and biodegradability, development of cyclic carbonates via carbonation of epoxy derivative at atmospheric pressure by adapting strategy via glycerol tosylate or succinic anhydride/glycerol carbonate to form 5-membered ring (two/three arms) to react with variety of diamines [11-13]. The choice of renewable polyols and cyclic carbonate derivative can be synthesized by execution of steps such as tosylation, epoxidation, condensation, nucleophilic substitution, transesterification, thiol-ene coupling ring opening polymerization etc., using renewable sources, isosorbide, menthone, castor oil and polycaprolactone polyols [14-16].