Hydrolytically-degradable homo- and copolymers of a strained exocyclic hemiacetal ester

Angelika E. Neitzel, Leonel Barreda, Jacob T. Trotta, Grant W. Fahnhorst, Thomas J. Haversang, Thomas R. Hoye, Brett P. Fors, Marc A. Hillmyer

Research output: Contribution to journalArticle

Abstract

We report the cationic ring-opening homo- and copolymerization of the 7-membered exocyclic hemiacetal ester 7-methoxyoxepan-2-one (MOPO) to afford poly(7-methoxyoxepan-2-one) [poly(MOPO)] and its copolymers with isobutyl vinyl ether (IBVE) that achieve essentially quantitative conversions of MOPO. The amorphous homopolymer is characterized by a low glass transition temperature of Tg = -37 °C and is readily degraded under both acidic and basic conditions at the labile acylacetal linkages. With triflic acid as the cationic initiator the homopolymerization proceeds by an uncontrolled active chain end mechanism to reproducibly yield poly(MOPO) of Mn ∼ 20 kg mol-1. The monomer was also polymerized by a photoinitiated process using a dithiocarbamate or trithiocarbonate chain transfer agent and the photocatalyst 2,4,6-tris(p-4-methoxyphenyl)pyrylium tetrafluoroborate. Lower molar mass polymers were recovered at high initial concentrations of dithiocarbamate as compared to no chain transfer agent, indicating some ability to control polymer molar mass. Photoinitiated copolymerization of MOPO and IBVE afforded a tapered copolymer with MOPO-MOPO, IBVE-MOPO, and IBVE-IBVE linkages that degraded into low molar mass poly(IBVE) fragments in hydrochloric acid through hydrolysis of the acylacetal linkages resulting from ring-opened MOPO units in the backbone.

Original languageEnglish (US)
Pages (from-to)4573-4583
Number of pages11
JournalPolymer Chemistry
Volume10
Issue number33
DOIs
StatePublished - Sep 7 2019

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Homopolymerization
Ethers
Esters
Copolymers
Molar mass
Copolymerization
Polymers
Hydrochloric Acid
Transition Temperature
Hydrochloric acid
Photocatalysts
Glass
vinyl ether
Hydrolysis
Monomers
Acids

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Hydrolytically-degradable homo- and copolymers of a strained exocyclic hemiacetal ester. / Neitzel, Angelika E.; Barreda, Leonel; Trotta, Jacob T.; Fahnhorst, Grant W.; Haversang, Thomas J.; Hoye, Thomas R.; Fors, Brett P.; Hillmyer, Marc A.

In: Polymer Chemistry, Vol. 10, No. 33, 07.09.2019, p. 4573-4583.

Research output: Contribution to journalArticle

Neitzel, AE, Barreda, L, Trotta, JT, Fahnhorst, GW, Haversang, TJ, Hoye, TR, Fors, BP & Hillmyer, MA 2019, 'Hydrolytically-degradable homo- and copolymers of a strained exocyclic hemiacetal ester', Polymer Chemistry, vol. 10, no. 33, pp. 4573-4583. https://doi.org/10.1039/c9py00797k
Neitzel AE, Barreda L, Trotta JT, Fahnhorst GW, Haversang TJ, Hoye TR et al. Hydrolytically-degradable homo- and copolymers of a strained exocyclic hemiacetal ester. Polymer Chemistry. 2019 Sep 7;10(33):4573-4583. https://doi.org/10.1039/c9py00797k
Neitzel, Angelika E. ; Barreda, Leonel ; Trotta, Jacob T. ; Fahnhorst, Grant W. ; Haversang, Thomas J. ; Hoye, Thomas R. ; Fors, Brett P. ; Hillmyer, Marc A. / Hydrolytically-degradable homo- and copolymers of a strained exocyclic hemiacetal ester. In: Polymer Chemistry. 2019 ; Vol. 10, No. 33. pp. 4573-4583.
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AU - Trotta, Jacob T.

AU - Fahnhorst, Grant W.

AU - Haversang, Thomas J.

AU - Hoye, Thomas R.

AU - Fors, Brett P.

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N2 - We report the cationic ring-opening homo- and copolymerization of the 7-membered exocyclic hemiacetal ester 7-methoxyoxepan-2-one (MOPO) to afford poly(7-methoxyoxepan-2-one) [poly(MOPO)] and its copolymers with isobutyl vinyl ether (IBVE) that achieve essentially quantitative conversions of MOPO. The amorphous homopolymer is characterized by a low glass transition temperature of Tg = -37 °C and is readily degraded under both acidic and basic conditions at the labile acylacetal linkages. With triflic acid as the cationic initiator the homopolymerization proceeds by an uncontrolled active chain end mechanism to reproducibly yield poly(MOPO) of Mn ∼ 20 kg mol-1. The monomer was also polymerized by a photoinitiated process using a dithiocarbamate or trithiocarbonate chain transfer agent and the photocatalyst 2,4,6-tris(p-4-methoxyphenyl)pyrylium tetrafluoroborate. Lower molar mass polymers were recovered at high initial concentrations of dithiocarbamate as compared to no chain transfer agent, indicating some ability to control polymer molar mass. Photoinitiated copolymerization of MOPO and IBVE afforded a tapered copolymer with MOPO-MOPO, IBVE-MOPO, and IBVE-IBVE linkages that degraded into low molar mass poly(IBVE) fragments in hydrochloric acid through hydrolysis of the acylacetal linkages resulting from ring-opened MOPO units in the backbone.

AB - We report the cationic ring-opening homo- and copolymerization of the 7-membered exocyclic hemiacetal ester 7-methoxyoxepan-2-one (MOPO) to afford poly(7-methoxyoxepan-2-one) [poly(MOPO)] and its copolymers with isobutyl vinyl ether (IBVE) that achieve essentially quantitative conversions of MOPO. The amorphous homopolymer is characterized by a low glass transition temperature of Tg = -37 °C and is readily degraded under both acidic and basic conditions at the labile acylacetal linkages. With triflic acid as the cationic initiator the homopolymerization proceeds by an uncontrolled active chain end mechanism to reproducibly yield poly(MOPO) of Mn ∼ 20 kg mol-1. The monomer was also polymerized by a photoinitiated process using a dithiocarbamate or trithiocarbonate chain transfer agent and the photocatalyst 2,4,6-tris(p-4-methoxyphenyl)pyrylium tetrafluoroborate. Lower molar mass polymers were recovered at high initial concentrations of dithiocarbamate as compared to no chain transfer agent, indicating some ability to control polymer molar mass. Photoinitiated copolymerization of MOPO and IBVE afforded a tapered copolymer with MOPO-MOPO, IBVE-MOPO, and IBVE-IBVE linkages that degraded into low molar mass poly(IBVE) fragments in hydrochloric acid through hydrolysis of the acylacetal linkages resulting from ring-opened MOPO units in the backbone.

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