ɛ‐caprolactone and lactide polymerization promoted by an ionic titanium(IV)/iron(III) polynuclear halo‐alkoxide

Abstract

1 unity and proceeds through the coordinationinsertion mechanism. Molecular weights ranging from 6,379 to 13,950 g mol 21 and PDI values varying from 1.22 to 1.52 were obtained. Results of ROP kinetic studies for both E-CL and rac-LA confirm that the reaction rates are first-order with respect to monomers. The production of poly(E-caprolactone) shows a higher sensitivity of the reaction rate to temperature, while the polymerization of rac-LA is slower and more dependent on the thermal stability of the active species during the propagation step.

Effects of hydrophobic core components in amphiphilic PDMAEMA nanoparticles on siRNA delivery

“…Besides, cationic NPs using poly(D,L-lactic acid) (PDLLA) as the hydrophobic core performed better DNA delivery effect than PCL in vitro [28]. Structurally, PCL is a kind of semi-crystalline polymer, and PDLLA presents a high glass transition temperature [29]. Therefore, nanoparticles formed by amphiphilic polycations with these polyesters have quite stiffer cores.…”

Improved Reactivity in the Ring-Opening Polymerization of ε-Caprolactone with a Trinuclear Titanium(IV) Oxochloroneopentoxide as Initiator

“…The current work adds to our earlier reports on the reactivity of polynuclear iron(II/III) and titanium(IV) alkoxides 31,32 and their use as initiators in the polymerization of cyclic esters. Good results have already been described for [Ti 3 (O i Pr) 11 ][FeCl 4 ] (A, Figure S1) 33 and [FeCl{Ti 2 (O i Pr) 9 }] 34 in the polymerization of both rac-LA and ε-CL, with particularly promising data obtained for the lactide monomer. The reactivity of the ionic complex A was studied in bulk, while [FeCl{Ti 2 (O i Pr) 9 }] was employed in toluene solution and in bulk.…”

“…Compound B seemed to be a promising initiator because the methylene group of the ONep − ligand works as an spacer between the metal ion and the bulky tert-butyl ligand head; its presence could facilitate monomer access to the Lewis acid sites in the alkoxide complex when compared to the more hindered isopropyl groups present in A. Results are compared in this work with those obtained from the parent alkoxide A, 33 employed here for the first time as ROP initiator in toluene solution, and other similar complexes described in the literature.…”

Boric acid as biocatalyst for living ring-opening polymerization of ε -caprolactone

“…[19][20][21] Various metals have been investigated as catalysts for ROP of cyclic esters, such as Al, Zn, Ti, Sn, Mg and Ca. [22][23][24][25] In health-related uses, difficulties in removing metal catalyst residues from the polymers have led to an increasing interest in the development of biocompatible catalysts. Organocatalytic polymerizations have been developed as one of the most useful methods for producing metal-free polymers, which is critically important for biomedical and pharmacological applications.…”