Exceptional copolymerizability of <i>o</i>-phthalaldehyde in cationic copolymerization with vinyl monomers

Hayashi, Keisuke; Kanazawa, Arihiro; Aoshima, Sadahito

doi:10.1039/c9py00547a

Cited by 14 publications

(27 citation statements)

References 33 publications

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“…Therefore, depolymerization (unzipping) via the backbiting reaction at the oxonium chain end (Scheme D, left), which occurs below the equilibrium concentration of MDOP, was most likely suppressed when an ester bond with a CL unit exists next to the oxonium chain end (Scheme D, right). This result is partially similar to the copolymerization of nonhomopolymerizable monomers. − …”

supporting

confidence: 68%

Tandem Unzipping and Scrambling Reactions for the Synthesis of Alternating Copolymers by the Cationic Ring-Opening Copolymerization of a Cyclic Acetal and a Cyclic Ester

2019

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Cationic copolymerization of different types of monomers, 4-hydroxybutyl vinyl ether (HBVE) and ε-caprolactone (CL), was explored using EtSO3H as an acid catalyst, producing copolymers with a remarkably wide variety of compositions and sequences. In the initial stage of the reaction, HBVE was unexpectedly isomerized to 2-methyl-1,3-dioxepane (MDOP), followed by concurrent copolymerization of MDOP and CL via active chain end and activated monomer mechanisms, respectively. The compositions and sequences of the copolymers were tunable, depending on the initial monomer concentrations. Moreover, a unique method was developed for transforming a copolymer with no CL homosequences into an “alternating” copolymer by removing MDOP from the system using a vacuum pump. This was achieved by the tandem reactions of depolymerization (unzipping) and random transacetalization (scrambling) under thermodynamic control. Specifically, the unzipping of HBVE homosequences proceeded at the oxonium chain end until a nondissociable ester bond emerged next to the chain end, while the scrambling of the main chain via transacetalization transferred midchain HBVE homosequences into the polymer chain end.

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supporting

confidence: 68%

Tandem Unzipping and Scrambling Reactions for the Synthesis of Alternating Copolymers by the Cationic Ring-Opening Copolymerization of a Cyclic Acetal and a Cyclic Ester

2019

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“…Based on previous work on the copolymerization of phthalaldehydes, the copolymerization of the allylated phthalaldehyde and unfunctionalized phthalaldehyde was investigated. [20,22,47] The allylated monomer was successfully incorporated in the copolymerization in a manner that allows variability in cross-linking density. It was found that a 1:1 equivalence of monomers was optimal for high incorporation rates (2.5:1 PPA:Allyl PPA) of the allylated monomer as well as the best overall yields of the statistical copolymer (Table S1, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Stimuli‐Responsive Depolymerization of Poly(Phthalaldehyde) Copolymers and Networks

Soars

Kamps

Fairbanks

et al. 2021

Macro Chemistry & Physics

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This article describes a stimuli-responsive cross-linked network based on a poly(phthalaldehyde) (PPA) self-immolating polymer backbone which, upon removal of polymer end-caps, becomes degradable under ambient conditions. Self-immolating polymers (SIPs) are of particular interest due to their ability to undergo controlled depolymerization resulting in the elimination of the polymer structure and potential recovery and reuse of the original monomers. Linear copolymers of phthalaldehyde and unsymmetrical allylated-phthalaldehyde monomers are obtained via anionic polymerization with appreciable incorporation of the allyl-functional monomeric units. This approach enables crosslinking of the otherwise linear polymers via thiol-ene reactions with the allyl functional phthalaldehyde polymers. The polymer network thus formed unzips along the phthalaldehyde backbone to yield monomers and low molecular weight fragments in response to chemical (F − , H + ) or physical (light, sonication) stimuli that remove the stabilizing functional endcaps on the phthalaldehyde polymers. Rheology is used to demonstrate gelation within 5 s of light exposure of the allylated-phthalaldehyde polymers reacted with pentaerythritol tetrakis(3-mercaptopropionate) and photoinitiator (3 wt%). Triggerable degelation makes this material well suited for photolithography and additive manufacturing as well as other applications that necessitate polymer network degradation or elimination. Further, a method is described for determining the degelation temperature of a self-immolative cross-linked network.

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“…EMPE, a β,β-dimethyl VE, was completely inert in the terpolymerization, probably due to steric hindrance (entry 10). Notably, the inefficiency of DHP and EMPE, which are small and nonhomopolymerizable, respectively, ,, is in sharp contrast to the alternating copolymerizations of these monomers with o -phthalaldehyde . Steric hindrance between these vinyl monomers and the MEK-derived carbocation is likely responsible for their inertness (Scheme C).…”

Section: Results and Discussionmentioning

confidence: 99%

“…Notably, the inefficiency of DHP and EMPE, which are small and nonhomopolymerizable, respectively, 35,39,40 is in sharp contrast to the alternating copolymerizations of these monomers with o-phthalaldehyde. 41 Steric hindrance between these vinyl monomers and the MEK-derived carbocation is likely responsible for their inertness (Scheme 4C). From these results, VEs with appropriate reactivities were demonstrated to be important to both suppress VE homopropagation and generate polymers with sufficiently high MWs.…”

Section: Table 1 Cationic Terpolymerization Of Various Ves With Vcho ...mentioning

confidence: 99%

ABC Pseudo-Periodic Sequence Control by Cationic Orthogonal Terpolymerization of Vinyl Ether, Oxirane, and Ketone

2019

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For the purpose of achieving ABC-type periodic terpolymers, various vinyl ethers (VEs), oxiranes, and ketones were examined in the cationic vinyl-addition, ring-opening, and carbonyl-addition terpolymerization and suitable reaction conditions were identified. When the appropriate monomers are employed, the terpolymerization proceeds via a one-way cycle of crossover reactions, similar to “rock-paper-scissors”. Homopropagation reactions of VE and oxirane need to be completely suppressed while attaining highly selective crossover reactions to achieve ABC-type periodic sequence control. By screening various monomers, VEs and oxiranes with moderate but sufficiently high reactivities were found to be appropriate for both the frequent crossover reactions and the polymerization itself. Appropriate ketones were also important for achieving efficient terpolymerization. In addition, more frequent crossover reactions occurred in the terpolymerizations conducted in less polar solvents at lower temperatures. Under the optimized conditions, the cationic terpolymerization of ethyl VE, 4-vinyl-1,2-cyclohexene oxide, and methyl ethyl ketone proceeded via frequent crossover reactions, and this process yielded an ABC pseudo-periodic terpolymer with averages of 1.2, 1.4, and 1.0 monomer units per block, respectively.

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Exceptional copolymerizability of o-phthalaldehyde in cationic copolymerization with vinyl monomers

Abstract: o-Phthalaldehyde is copolymerized via the unique active species, which allows the controlled copolymerization with alkyl vinyl ethers, alternating copolymerization, and copolymerization with sterically hindered nonhomopolymerizable vinyl monomers.

Cited by 14 publications

References 33 publications

Tandem Unzipping and Scrambling Reactions for the Synthesis of Alternating Copolymers by the Cationic Ring-Opening Copolymerization of a Cyclic Acetal and a Cyclic Ester

Tandem Unzipping and Scrambling Reactions for the Synthesis of Alternating Copolymers by the Cationic Ring-Opening Copolymerization of a Cyclic Acetal and a Cyclic Ester

Stimuli‐Responsive Depolymerization of Poly(Phthalaldehyde) Copolymers and Networks

ABC Pseudo-Periodic Sequence Control by Cationic Orthogonal Terpolymerization of Vinyl Ether, Oxirane, and Ketone

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