Controlled degradation and functionalization of natural rubber by ozonolysis in organic solvent

Hydroxyl-terminated natural rubber can be used as an eco-friendly and renewable bio-based polyol for the production of sustainable polyurethanes. It can also have other advantages such as high elasticity and thermal stability over many other conventional polyols. Liquid natural rubber (LNR) with primary and secondary hydroxyl end-groups was prepared via ozonolysis of natural rubber (NR) in chloroform at 60 degrees C followed by the subsequent reduction with sodium borohydride. M-n and M-w of the prepared hydroxyl-telechelic liquid natural rubber were 2368 g/mol and 3949 g/mol, respectively. The prepared liquid natural rubber has a narrow unimodal molecular weight distribution and a relatively low polydispersity index of 1.9. The presence of terminal hydroxyl groups and cis-1,4-isoprenic microstructures of hydroxyl-telechelic liquid natural rubber were determined by FT-IR, H-1 and C-13 NMR spectroscopy. The prepared hydroxyl-telechelic liquid natural rubber was successfully cured with toluene diisocyanate (TDI) and a polyurethane elastomer was obtained.