Vinyl　polymer　tacticity　is　critical　for　regulating　the　thermal　and　physical　properties　of　materials.　Stereoselective　cationic　polymerization　of　vinyl　ethers　has　gained　significant　progress　in　recent　years,　while　monomer　scope　beyond　simple　alkyl　vinyl　ethers　to　access　functionalized　isotactic　polymer　materials　remains　to　be　explored　but　highly　desirable.　Herein,　we　report　the　successful　development　of　a　stereoselective　cationic　polymerization　of　alkenyl　vinyl　ethers　by　employing　confined　Brønsted　acid　organocatalysis.　This　organocatalytic　system　shows　high　efficiency　and　stereoselectivity　in　the　polymerization　of　several　alkenyl　vinyl　ethers,　as　well　as　good　compatibility　to　the　diolefinic　monomers　without　touching　the　C=C　bonds　in　the　alkenyl　part　during　the　cationic　polymerization,　thus　allowing　for　further　modification　on　these　C-C　double　bonds　after　polymerization　to　construct　functionalized,　isotactic　polymer　materials.　Further,　a　series　of　thermoplastic　copolymers　with　tunable　properties　and　variable　and　predictable　contents　of　side-chain　C=C　bonds　can　be　synthesized　through　the　corresponding　stereoselective　copolymerization.　Sequential　post-polymerization　modification　of　both　isotactic　homopolymers　and　copolymers　by　combining　thiol-ene　and　sulfur(VI)　fluoride　exchange　(SuFEx)　click　reactions　is　also　demonstrated.　©　2023　The　Author(s)