Ring‐opening polymerization of 1,4‐dioxan‐2‐one initiated by lanthanum isopropoxide in bulk

Abstract

Lanthanum isopropoxide (La(OiPr)3) has been synthesized and employed for ring‐opening polymerization of 1,4‐dioxan‐2‐one in bulk as a single‐component initiator. The influences of reaction conditions such as initiator concentration, reaction time, and reaction temperature on the polymerization were investigated. The kinetics indicated that the polymerization is first‐order with respect to the monomer concentration. The Mechanistic investigations according to 1H NMR spectrum analysis demonstrated that the polymerization of PDO proceeded through a coordination‐insertion mechanism with a rupture of the acyl‐oxygen bond of the monomer rather than the alkyl‐oxygen bond cleavage. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5214–5222, 2008

Rapid ring‐opening polymerization of 1,4‐dioxan‐2‐one initiated by titanium alkoxides

“…ROPs of lactone41 and lactide37, 45 initiated by titanium alkoxides occur via a coordination‐insertion mechanism. This mechanism was proved to exist in the ROP of PDO initiated by Al(O i Pr) 3 20 and La(O i Pr) 3 33. Therefore, it is reasonable to suppose that the coordination‐insertion mechanism operates in the ROP of PDO initiated by titanium alkoxides in this study.…”

“…When ROP of PDO was initiated by Al(O i Pr) 3 20 and La(O i Pr) 3 ,33 there were only 1.3 effective alkoxides in both cases, which indicated that not all the three O i Pr groups are able to initiate the ROP of PDO. In this study, we have also estimated the effective alkoxide initiation sites of the individual titanium alkoxides.…”

“…It has been revealed that the ROP of ε‐caprolactone,35, 36 lactide,38 and cyclic carbonates39, 40 initiated by titanium alkoxides occurs via the cleavage of acyl–oxygen bond. In addition, the ROP of 1,4‐dioxan‐2‐one initiated by Al(O i Pr) 3 20 and La(O i Pr) 3 33 also occurs with cleavage of acyl–oxygen bonds.…”

“…In addition, zinc lactate (Zn(Lac) 2 ),21 enzymes,5 and lanthanum isopropoxide (La(O i Pr) 3 )33 have also been reported to initiate the ROP of 1,4‐diaxon‐2‐one. However, problems have been encountered when using these initiators, for example, low ultimate conversion of monomer (86%) with La(O i Pr) 3 as a catalyst,33 low activity of Zn(Lac) 2 and enzymes, to mention a few. Thus, new initiators with high activity and efficiency are still desirable for the efficient mass production of PPDO.…”

Synthesis of metal‐free poly(p‐dioxanone) by phosphazene base catalyzed ring‐opening polymerization

“…17,18 Furthermore, PPDO has proven to be tougher than PLA and even high-density polyethylene with a tensile strength of approximately 7000 psi for an ultimate elongation ranging from 500% to 600%. [21][22][23][24][25][26] Because PPDO has potential applications in the biomedical and pharmaceutical industries either as biodegradable implants or in controlled drug-delivery systems, it is necessary to remove all the traces of the metallic residues. 20 In general, PPDO can be synthesized by the ring-opening polymerization (ROP) of p-dioxanone (PDO) using metallic catalysts such as tin(II) bis(2-ethylhexanic acid), triethylaluminum, aluminum alkoxides, zinc derivatives, ferric alkoxides, titanium alkoxides, and yttrium complexes.…”