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

Abstract

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 radicalinitiated 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.

Stereochemical enhancement of polymer properties

“…Synthetically it is possible to produce other stereo-controlled polyhydroxyalkanoates with controlled alternating microstructures [100][101][102] that may yield promising new functional materials. Furthermore, there is interest in producing copolymers by combining PHB with other polyhydroxyalkanoates [103][104][105][106][107][108][109][110] or PLLA 104,[111][112][113][114][115][116] in order to modulate material properties; however, the stereochemistry of PHB has only been controlled in a few cases. [109][110][111]115,116 Taking stereochemistry into consideration in such systems should afford many interesting opportunities for biomedical applications.…”

Hybrid monomer design for unifying conflicting polymerizability, recyclability, and performance properties

“…42 Thus, it remains a challenging task to combine several desired, but conflicting, properties into one lactone monomer. As copolymerization of two or more different monomers is considered as an effective strategy to obtain the materials with tailored properties by adjusting the chemical nature, composition, and sequence of the comonomers, often delivering improved or unattainable properties in relation to those of the constituent homopolymers, [44][45][46][47][48][49][50][51] it thus became an attractive strategy to address the trade-off issues. In this context, the LCT g-BL was copolymerized with high ceiling temperature (HCT) and strained seven-membered ε-caprolactone (ε-CL) 52,53 to produce copolymers aimed for enhanced polymerizability and thermal stability for PGBL, and degradability and recyclability for poly(ε-caprolactone) (PCL).…”

Ligand‐Controlled Palladium‐Catalyzed Carbonylation of Alkynols: Highly Selective Synthesis of α‐Methylene‐β‐Lactones

“…Here,the vinylidene groups of the lactones could be further functionalized, producing well-defined blocks with designable segments. [2] In organic chemistry,t he high degree of functional groups in ac ompact manner allows diverse synthetic utilizations and makes this class of compounds interesting building blocks. [3] More specifically,owing to their inherent strain in the four-membered ring, they readily undergo ring opening reactions with aw ide range of nucleophiles by either acyl C À Oo ra lkyl C À Ob ond cleavage.…”