Synthesis of Poly(ε-caprolactone) with a Stable Nitroxyl Radical as an End-Functional Group and Its Application to a Counter Radical for Living Radical Polymerization

Abstract

The quantitative synthesis of poly(ε-caprolactone) (PCL) with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) at one chain end was attained through the anionic polymerization of CL by an aluminum tri(4-oxy-TEMPO), which was prepared by the reaction of triethylaluminum and 4-hydroxy-TEMPO. The TEMPO-supported PCL behaved as a polymeric counter radical for the radical polymerization of styrene, giving poly(CL-block-styrene) in quantitative efficiency. The radical polymerization was found to proceed in accordance with a living mechanism, because the conversion of styrene linearly increased over time, and the molecular weight was directly proportional to the reciprocal of the initial concentration of the PCL. The resulting copolymers had two glass transition temperatures due to the PCL block and polystyrene and one melting endotherm based on the crystalline phases of PCL. The TEM picture of the film obtained from the block copolymer demonstrated microphase segregation.

Synthesis of Poly(ethylene adipate) with a Stable Nitroxyl Radical at Both Chain Ends, and Applications to a Counter Radical for Living Radical Polymerization

“…The rate of polymerization was much faster with TEMPO supported on polymers, than that with TEMPO of low molecular weight, such as 4-methoxy-TEMP0. 6 • 19 • 20 Therefore, the two-step procedure of heating was used to give block copolymers with narrow polydispersities, by dividing the initiation from the propagation. 8 It is also expected that uncontrolled-polymerization of styrene proceeds more easily in polymerization by TEMPO-supported polymers than that by low-molecular weight TEMPO, because mobility of TEMPO is restrained by PEA chain attached to TEMPO.…”

“…We released a publication on the synthesis of poly(a-caprolactone) with a stable nitroxyl radical at the terminal. 6 The nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) is known as an anti-oxidant, and as a mediator for the oxidation of alcohols by copper(II). 7 This radical also serves as an efficient counter radical for living radical polymerization of 15 and its 18 giving polymers with narrow polydispersities.…”

Study of a new titanium dual initiator for the synthesis of poly(ε‐caprolactone)‐b‐polystyrene block copolymers by the combination of coordination and nitroxide mediated polymerizations

“…In the literature, many publications concern the alkoxyamine TEMPO terminated PCL. Mecerreyes et al introduced PCL brushes at the surface of an electrically conducting material, 13 Yoshida and Osagawa synthesized PCL block PS using aluminum tri(4-oxy-TEMPO) as initiator, 3 Huang and coworkers prepared PCL-PS grafted PEO and PCL-b-poly(4-vinyl pyridine). 4,5 It is important to indicate that among the mentioned articles, only aluminum initiator was used.…”

Synthesis and properties of polyurethane ionomers based on carboxylated polycaprolactone

“…Then the salt groups might be distributed in the polymer matrix in the form of ion pairs or multiplets, and no clusters would exist, because PCL is known for its good compatibility, 7 and carboxylate is more advantageous to ionic aggregate dissociation than the sulfonate group. 2 In this study, the carboxylate group was introduced into the PCL soft segment, and based on this, a new family of polyurethane ionomers was prepared.…”