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Environmental fate & pathways

Hydrolysis

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Description of key information

DT50 > 1 yr (HYDROWIN v2.00)

Key value for chemical safety assessment

Additional information

No experimental data are available on the hydrolysis of UMA 121. However, based on its molecular structure and poor solubility in water, hydrolysis is not expected to occur under environmental conditions. In order to support this assumption, QSAR calculations were performed for the smallest constituents present within UMA 121. UMA 121 is the reaction product of the following substances:

- Methylendiphenyldiisocyanate, isomer mixture of 4,4’- and 4,2’-MDI (MDI) CAS No. 26447-40-5

- Dipropylene glycol (DPG) CAS No. 25265-71-8

- 2 -hydroxypropylmethacrylate (HPMA) CAS No. 27813-02-1

The reaction product is a solid resin containing the polymer HPMA-MDI-(DPG-MDI)n-HPMA as homologues of n = 0, 1, 2, 3, etc. (no upper limit defined) as well as free HPMA. Calculations were performed for the UMA homologues HPMA-MDI-HPMA (n=0) and HPMA-MDI-DPG-MDI-HPMA (n=1) and for HPMA. Larger homologues (n>1) are highly insoluble in water and therefore not relevant for hydrolysis. All calculations resulted in half-lives > 1 year at pH 7 and 8. Therefore, hydrolysis is not expected to be relevant for UMA 121 at environmental conditions.