Chain extension of caprolactone and ethylene glycol macrodiols into hydroxyl-terminated polyurethanes

Polyurethane (PU) plastics are widespread in various areas such as adhesives, coatings, synthetic leather, etc. [1]. Frequently, PU plastics are synthesized from two components: 1) macrodiols and 2) isocyanates, whose reactions form urethane linkages [2]. The macrodiol must contain two OH groups with a polyether, polyester, hydrocarbon, polycarbonate or other type of spacer chain in between. Quite often, the macrodiol is pre-reacted with diisocyanates for chain extension and only then cross-linked into the final PU plastic. Resulting properties also depend on molecular weights, degree of crystallinity and morphology of PU polymers [3] in addition to the consequences of many side reactions, such as CO2 evolution.

Also available on pg 90 of http://www.journals.vu.lt/proceedings/article/view/12830/11636