Functionalized Polyesters with Tunable Degradability Prepared by Controlled Ring-Opening (Co)polymerization of Lactones

Various well-defined diblock copolymers with poly(α-methylene−β-butyrolactone) (PM β BL) segment were prepared by salen–aluminum complexes or aminoalkoxybis(phenolate)yttrium amido complex mediated living ring-opening polymerization of racemic α-methylene-β-butyrolactone ( rac -M β BL) and different lactones via one-pot, two-step method. These diblock copolymers all consist of semicrystalline and amorphous segments, possessing both a melting point and a glass transition temperature. With the use of simple salenAlMe with bulky ( tert -butyldimethylsilyl) groups on the phenolate ortho position as catalyst in conjunction with equivalent benzyl alcohol, M β BL and β-butyrolactone (BL) have nearly identical reactivity in their copolymerization, affording the copolymers P(M β BL- ran -BL) with random distributions of the two monomers. Notably, these copolymers exhibited tunable degradability in the presence of Lewis base, dependent on the M β BL unit content in the random copolymers. Moreover, the vinylidene groups in P(M β BL- ran -BL) copolymers could be further functionalized through radical-initiated cross-linking reactions and thiol–ene click chemistry, producing functionalized and cross-linking polymers with enhanced thermal property. These strategies will provide enormous possibilities to synthesize diverse well-defined block and random copolymers with designable segments or functional groups.