A Library of Well-Defined and Water-Soluble Poly(alkyl phosphonate)s with Adjustable Hydrolysis

Poly(alkyl ethylene phosphonate)s with different alkyl side chains exhibit significant differences in their degradation behavior. Three novel 2-alkyl-2-oxo-1,3,2-dioxaphospholanes, cyclic monomers for the ring-opening polymerization (ROP) toward poly(alkyl alkylene phosphonate)s, were synthesized by 0 robust two- or three-step protocols in reasonable yields and high purity. The polymerization was promoted by the organocatalysts 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and proceeded with high control over molecular weight and narrow molecular weight distributions (D < 1.2) up to full conversion. These polymers with methyl, ethyl, and isopropyl side chains are perfectly soluble in water (up to 25 mg mL(-1)) without a temperature-dependent phase separation. They showed no toxicity against He La cells after 24 h of incubation at any tested concentration. Polymers with butyl side chains exhibit decreased solubility and concentration-dependent cloud point temperatures and show toxicity against He La cells at concentrations above 25 mu g mL(-1). The polymers showed no acetylcholinesterase inhibition. All polymers exhibited significantly different degradation times under both neutral as well as basic conditions (variation of the alkyl side chain allowed stabilities from 8 h up to 6 days).