Method of preparing polyurethanes from oligomeric polyol compositions and polyisocyanates

There is provided an oligomeric polyol composition having (a) an oligomeric network containing residues of at least one polyhydroxylated aromatic compound and residues of at least one polyol having at least three hydroxyl groups; and (b) a plurality of peripheral groups having one or more pendant hydroxyl groups bound to the oligomeric network by a plurality of linking units. The residues of the polyol may optionally contain one or more oxygen ether groups, one or more amino ether groups, or both of one or more oxygen ether groups and one or more amino ether groups. Reaction of the oligomeric polyols with isocyanate monomers affords a new class of polyurethanes having superior heat and water resistance. The new polyurethanes exhibit lower peak exotherms, typically less than 250° F. during in-mold polymerization. Articles prepared from polyurethanes incorporating such oligomeric polyol compositions exhibit flexural strengths and moduli in excess of 10,000 psi and 400,000 psi respectively, and outstanding green strength.