Synthesis of\nDegradable Homopolymer, Gradient and\nBlock Copolymers, and Self-Assembly via RAFT Polymerization of 4,4-Dimethyl-2-methylene-1,3-dioxolan-5-one

Reversible addition–fragmentation chain transfer\npolymerizations\nof 4,4-dimethyl-2-methylene-1,3-dioxolan-5-one (DMDL) were conducted\nto yield degradable polymers with low dispersities. As well as homopolymers,\nrandom copolymers and block copolymers were synthesized by combining\nDMDL with various hydrophobic and hydrophilic monomers such as (functional)\nmethacrylates, acrylates, and acrylamides, which are the so-called\n“more activated” monomers, and vinyl acetate and vinylpyrrolidone,\nwhich are the so-called “less activated” monomers. The\nobtained polymers were demonstrated to degrade under basic conditions.\nIn the studied systems, random polymerization tended to yield gradient\ncopolymers shifting from comonomer-rich segments to DMDL-rich segments,\nowing to the largely different reactivities of DMDL and comonomers.\nSuch gradient copolymers may exhibit properties similar to those of\nblock copolymers. Gradient copolymers with hydrophilic vinylpyrrolidone\nsegments and hydrophobic DMDL-rich segments were synthesized and used\nto generate self-assemblies, i.e., micelles and vesicles, in water.\nThe generated self-assemblies were demonstrated to degrade under basic\nconditions.