Easy degradable polymeric gel with extremely base-labile cross-linking

- We prepared new kinds of degradable cross-linked polymeric gels.
- The gels were cross-linked with phenolic ester linkage.
- The polymeric gels with high ratio of PtBA can be degraded by NaHCO3 in methanol.
- These gels can be degraded by NaHCO3/H2O after PtBA was hydrolyzed into PAA.

A variety of cross-linkable block copolymers were studied to prepare cross-linked structure and nanoobjects which are stable in solvents; at the same time, some degradable core cross-linked star polymers and gels which can be degraded under catalysis were also reported. In this study, degradable chemical cross-linked poly(tert-butyl acrylate) gels were prepared with phenolic ester linkage, which can be cleaved effectively under extremely mild condition of NaHCO3. Post cross-linked gel was prepared via microphase separation of cross-linkable phenolic ester containing poly(glycidyl methacrylate)-(phenolic ester)poly(tert-butyl acrylate)-poly(glycidyl methacrylate) (PGMA-(PE)PtBA-PGMA) triblock copolymer, which was synthesized by atom transfer radical polymerization (ATRP). After microphase separation, the low volume ratio of PGMA formed nanospheres dispersed in the PtBA matrix and cross-linked by amine; chemical cross-linked gel was then obtained after swelling. In situ polymeric gel with higher phenolic ester bond density was prepared by copolymerization of tBA and phenolic ester containing difunctional monomer hydroquinone diacrylate (HDA) as cross-linker. These chemical cross-linked gels can be degraded into dispersed nanospheres and linear PtBA separately in NaHCO3/methanol. Moreover, the cross-linked gels can be hydrolyzed into PAA hydrogels by CF3COOH which can be degraded effectively by NaHCO3/H2O solution.