Base-Triggered Degradation of Poly(vinyl ester sulfone)s with Tunable Sensitivity

A series of poly(vinyl ester sulfone)s are synthesized and are found to rapidly degrade in the presence of base. Solution phase NMR indicates that the sensitivity of these polymers to base depends on the identity of the ester functional group of the polymers. From most to least sensitive these are poly(vinyl chloroacetate sulfone) > poly(vinyl acetate sulfone) > poly(vinyl benzoate sulfone) > poly(vinyl pivalate sulfone). Significantly, these polymers were more reactive to base than the aliphatic poly(1-hexene sulfone). Additionally, degradation of these polymers in bulk occurs rapidly with exposure to aqueous solutions of base. The polymers are stable in water and possess good barrier properties; films of 30 μm thickness allow on average <1% crossover of dye over 7 days. Based on the data collected, poly(vinyl ester sulfone) polymers are promising for use in microcapsules, in particular, for applications where sustained or staged release would benefit from a series of different microcapsule compositions.