A new cyclic initiator system for the synthesis of novel star-shaped polyether-polyols (PEPOs) for fabrication of rigid cross-linked polyurethanes

Abstract

Application of novel potassium salts (from mono- to penta-potassium) of 2,2,6,6-tetrakis(hydroxymethyl) cyclohexanol-activated 18C6 for propylene oxide polymerization is investigated. The novelty of the research concerns utilization of the cyclic-structured initiator with various substitution levels applied for anionic ROP of oxiranes. It results in the formation of bimodal macropentols (Scheme 1) with molar mass values in the range of Mn 2100–13200 g/mol and unsaturation, which depends on the initial concentration of monomer and alkoxide groups. The mechanism of the studied processes is discussed. The newly synthesized polyether-polyols (PEPOs) were used for the synthesis of new rigid polyurethanes (PURs) in one-step process. Thermogravimetric analysis (TGA) showed that the analyzed polyurethanes based on star-shaped polyols were characterized by two-stage thermal degradation and higher thermal stability in comparison to the linear polyols. The first stage of thermal decomposition of the tested PURs is related to the breaking of the urethane bonds in the rigid chains, while during the second stage, oligo-diol and oligo-pentol chains break down. A significant amount of solid degradation residue is advantageous in terms of the flame retardation of the obtained PUR, as this is usually associated with less products released during the degradation process. It was shown that the higher content of rigid segments in the PUR structure results in higher thermal resistance. The thermal behavior of the PURs was also investigated by differential scanning calorimetry (DSC).