Synthesis of Functional Poly(ε-caprolactone)s via Living Ring-Opening Polymerization of ε-Caprolactone Using Functionalized Aluminum Alkoxides as Initiators

Abstract

The new aluminum compounds 1–3 modified by unsaturated alcohol, Me3−nAl(O(CH2)4OCHCH2)n (n = 1 (1), 2 (2), 3 (3)), are synthesized and investigated by multinuclear (1H, 13C, 27Al) NMR spectroscopy. The compounds 1–3 initiate living ring‐opening polymerization of ε‐caprolactone in bulk at 40–80 °C to afford polyesters with controlled molecular weight (Mn up to 35 000 g mol−1) and relatively narrow molecular weight distribution (Mw/Mn < 1.8). Among initiators studied here, aluminum trialkoxide shows the highest activity, whereas aluminum dialkoxide is a less active. In all cases, the fragment of unsaturated alcohol is transferred to the end of the polymeric chain with high degree of functionality (>85%) yielding macromonomers. These macromonomers are copolymerized with maleic anhydride to give poly(vinyl ether‐co‐maleic anhydride)‐g‐poly(ε‐caprolactone) graft copolymers.

Measuring the Glass Transition Temperature of Vapor-Phase-Infiltrated AlOx-PS-r-PHEMA Organic–Inorganic Hybrid Thin-Film Materials

“…VPI of TMA + H 2 O is believed to potentially form inorganic clusters upon reaction within the polymer. 31 These clusters should be covalently bound to the copolymer chains and through condensation reactions could further aggregate to form high-functionality cross-links with effectively higher K 2 values. Irrespective of the exact mechanism, these observations suggest that VPI has the potential to more effectively reduce the polymer chain mobility than conventional organic crosslinker chemistries.…”

Copolyesters of ε-caprolactone and l-lactide catalyzed by a tetrabutylammonium phthalimide-N-oxyl organocatalyst

“…12 Aluminum complexes modied by varying the ligand were utilized to produce well-dened polymers with high catalytic efficiency and selectivity to ROP of lactones. 13,14 Zinc alkoxides were friendly substitution of Tin analogue due to their bioresorbable characteristic 15 and proved to be high effective for ROP of L-LA at room temperature with good control of polymer structure. 16 In recent years, the application of metal-free strategies to ROP reactions has been developed into an important aspect of the eld.…”

Ring‐opening polymerization of (Macro)lactones by highly active mononuclear salen–aluminum complexes bearing cyclic β‐ketoiminato ligand

“…Aluminum‐based complex is another promising candidate, in view of the Lewis acidity, cytotoxicity, and abundance of Al in the earth. Over the past few years, aluminum complexes coordinated with different types of ligands were designed and prepared, to obtain highly efficient precatalyst for ROP of cyclic esters and produce (co)polyesters with structural diversity . Among the various Al complexes, aluminum–salen complexes bearing salicylaldiminato moiety were found to be a versatile type of catalysts for ROP of both small ring‐sized lactones and macrolactone .…”

“…Over the past few years, aluminum complexes coordinated with different types of ligands were designed and prepared, to obtain highly efficient precatalyst for ROP of cyclic esters and produce (co)polyesters with structural diversity. [48][49][50][51][52][53][54] Among the various Al complexes, aluminum-salen complexes bearing salicylaldiminato moiety were found to be a versatile type of catalysts for ROP of both small ring-sized lactones and macrolactone. 9,[55][56][57][58][59] Meanwhile, this type of catalyst showed a certain of stereocontrol ability in the ROP of racemic LA (rac-LA), producing semicrystalline PLA from a mixture of L-LA and D-LA.…”