Ring‐opening polymerization of ε‐caprolactone via the bismuth‐2‐mercaptoethanol complex

Abstract

A complex consisting of one Bi3+ ion and two 2‐mercaptoethanol units (BiME2) was used as initiator for the ring‐opening polymerization of ε‐caprolactone in bulk. A kinetic comparison showed that BiME2 is as reactive as initiator as Sn‐octanoate and more reactive than Bi‐hexanoate. The difference to BiHex3 decreased at higher temperatures and upon addition of an alcohol as coinitiator. When tetra(ethylene glycol) was used as coinitiator, it was completely incorporated into the poly(εCL) chain, so that telechelic polylactones having two OH‐endgroups were formed. In the absence of a coinitiator, 2‐mercaptoethanol or its disulfide were incorporated in the form of ester groups. Furthermore, it was found by MALDI‐TOF mass spectrometry that small amounts of cyclic oligolactones (detected up to a degree of polymerization of 17) were formed under all reaction conditions. Higher temperatures and longer times favored a higher content of cycles. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3175–3183, 2006

Distinct topography of erosion and new bone formation in achilles tendon enthesitis: Implications for understanding the link between inflammation and bone formation in spondylarthritis

“…Chain extension of spirocyclic block copolymers built up for oligo‐ or poly(ethylene oxide) and poly( L ‐lactide) blocks by in situ reaction with sebacoyl chloride or 1,6‐hexamethylene diisocyanate yielded multiblock copoly(ether ester)s 240. Successful REPs of e‐caprolactone initiated by the Bi‐complex formulated in Scheme were also reported 243. However, attempts to stabilize the (spiro)cyclic structures of the resulting polymers have not been reported yet.…”

“…The first example (in the historic sequence) was the metathathesis polymerization of cyclooctene by means of a cyclic ruthenium carbene complex (Scheme ) 243. The polymerization mechanism may again be defined as a coordination insertion mechanism free of intermediate formation of linear chains.…”

Cyclic polymers: Synthetic strategies and physical properties

“…240,241 Chain extension of spirocyclic block copolymers built up for oligo-or poly(ethylene oxide) and poly(L-lactide) blocks by in situ reaction with sebacoyl chloride or 1,6-hexamethylene diisocyanate yielded multiblock copoly(ether ester)s. 240 Successful REPs of e-caprolactone initiated by the Bi-complex formulated in Scheme 54 were also reported. 243 However, attempts to stabilize the (spiro)cyclic structures of the resulting polymers have not been reported yet.…”

“…243 The polymerization mechanism may again be defined as a coordination insertion mechanism free of intermediate formation of linear chains. The molar masses of the resulting cyclic poly(octenamer)s paralleled roughly the monomer/initiator ratio and values up to 1.2 kDa were achieved.…”

Controlled ring‐opening polymerization of ε‐caprolactone using polymer‐supported scandium catalyst

“…1 Metal complexes are the most commonly explored catalysts; they include tin, 2,3 aluminum, [4][5][6][7] iron, 8,9 scandium, [10][11][12] yittrium, 13,14 zinc, 15,16 bismuth, 17 ruthenium, 18 zirconocene, 19 and so on. A popular polymerization system for PCL is ring-opening polymerization (ROP) of ecaprolactone catalyzed by organotin compound.…”