Determination of ceiling temperature and thermodynamic properties of low ceiling temperature polyaldehydes

Schwartz, Jared M.; Engler, Anthony; Phillips, Oluwadamilola; Lee, Ji‐Hyun; Kohl, Paul A.

doi:10.1002/pola.28888

Cited by 21 publications

(30 citation statements)

References 28 publications

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“…To do so, a variable-temperature 1 H NMR spectroscopic method was adapted from a protocol by Kohl and co-workers (SI pgs 72-97). 20 Solutions with known initial concentrations of monomer ([M]0) and catalyst were prepared. Then, the monomer concentration ([M]) was measured at different temperatures by integrating the aldehyde C-H resonance versus an internal standard.…”

Section: Scheme 2 Model Reaction For Phthalaldehyde Polymerizationmentioning

confidence: 99%

Functionalized and Degradable Polyphthalaldehyde Derivatives

Lutz¹,

Davydovich²,

Hannigan³

et al. 2019

Preprint

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<div><p>Polymers that depolymerize back to monomers can be repeatedly chemically recycled, thereby reducing their environmental impact. Polyphthalaldehyde is a metastable polymer that is rapidly and quantitatively depolymerized due to its low ceiling temperature. However, the effect of substitution on the physical and chemical properties of polyphthalaldehyde derivatives has not been systematically studied. Herein, we investigate the cationic polymerization of seven distinct <i>o</i>‑phthalaldehyde derivatives and demonstrate that judicious choice of substituents results in materials with a wide range of ceiling temperatures (from < –60 to 106 °C) and decomposition temperatures (109–196 °C). We anticipate that these new polymers and their derivatives will enable researchers to access degradable materials with tunable thermal, physical, and chemical properties.</p></div>

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Section: Scheme 2 Model Reaction For Phthalaldehyde Polymerizationmentioning

confidence: 99%

Functionalized and Degradable Polyphthalaldehyde Derivatives

Lutz¹,

Davydovich²,

Hannigan³

et al. 2019

Preprint

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“…Moore et al introduced the concept of stimuli‐responsive polymers such as poly(phthalaldehyde) (PPHA) as a metastable material that can be used for a variety of transient device applications . Low ceiling temperature polymers, such as PPHA, are thermodynamically unstable above their ceiling temperature and can be kinetically stabilized by end‐capping or cyclization of the chains for use above their ceiling temperature . The removal of the kinetic‐trap can induce rapid, unzipping depolymerization at room temperature .…”

Section: Introductionmentioning

confidence: 99%

“…7,8 Low ceiling temperature polymers, such as PPHA, are thermodynamically unstable above their ceiling temperature and can be kinetically stabilized by end-capping or cyclization of the chains for use above their ceiling temperature. [9][10][11][12] The removal of the kinetic-trap can induce rapid, unzipping depolymerization at room temperature. 13,14 The PPHA backbone is susceptible to cleavage via free-acid protonation of the acetal linkage.…”

Section: Introductionmentioning

confidence: 99%

Time‐delayed photo‐induced depolymerization of poly(phthalaldehyde) self‐immolative polymer via in situ formation of weak conjugate acid

Jiang

Phillips

Engler

et al. 2019

Polymers for Advanced Techs

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Poly(phthalaldehyde) (PPHA) can be used as a structural material in transient devices and photo‐catalytically depolymerized at the end of device life by the use of a photo‐acid generator (PAG). However, device degradation requires the presence of a radiation source at the end of device mission. It has been found that the onset of PPHA depolymerization after PAG photo‐exposure can be delayed by incorporation of a particular weak bases in the PPHA/PAG mixture. This method of delayed PPHA depolymerization allows for PAG activation prior to or during device deployment when the device is under full user control. The basicity of specific lactams and amides was found to slow the PPHA depolymerization, giving the transient device a longer but finite mission lifetime. The weak base reacts with the photo‐generated strong acid to form a weak conjugate acid, which reacts more slowly with PPHA to extend the onset of PPHA depolymerization. The addition of a molar excess of specific lactams or amides, with respect to PAG, maintains PPHA stability and mechanical properties for more than 80 minutes after photo‐exposure at room temperature. The amide or lactam mediated acid activation of PPHA follows first‐order kinetics. The time delay of PPHA depolymerization can allow for prelaunch photo‐exposure and eliminates the need for postmission photo‐exposure where reliable light‐sources may not be available.

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“…Polyaldehydes are a family of self‐immolative polymers that have been use as substrates for transient devices . In particular, poly(phthalaldehyde) (PPHA) is highly sensitive to acids and will promptly depolymerize into monomer units by end‐cap removal or direct chain attack at or below room temperature . PPHA with volatile, aldehyde copolymers have been synthesized and shown to have fast depolymerization and vaporization times …”

Section: Introductionmentioning

confidence: 99%

Sunlight photodepolymerization of transient polymers

Phillips

Engler

Schwartz

et al. 2018

J of Applied Polymer Sci

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The study and development of transient devices is an emerging field where the disposal of a device after use is desired to avoid reverse engineering and minimize the environmental impact. Polyaldehydes with phototriggers have been investigated because the radiation wavelength can be adjusted to meet the transient application. Polynuclear aromatic hydrocarbons (PAHs) were used as the optical sensitizer for photoacid generators (PAGs). Photoinduced electron transfer (PET) with an iodonium-based PAG was used to expand the spectral sensitivity range. Anthracene, tetracene, and pentacene derivatives were synthesized with appended phenylethynyl groups to improve the solubility of the sensitizer and adjust the absorption wavelength. Sensitization of the iodonium-based PAG with the PAH derivatives was found to have thermodynamically favorable PET reactions for depolymerization of poly(propylene carbonate) and poly(phthalaldehyde) (PPHA). The Rehm-Weller equation and Stern-Volmer analysis were used to study the electron transfer and the fluorescence quenching rates of the PAHs with the iodonium salts, respectively. The photosensitivity, efficiency, and byproducts of the PET reactions in the decomposable polymer films are reported. A rapid photoreaction is reported for the depolymerization of PPHA exposed to a sunlight dose of <6 J cm −2 (i.e., 1 min of direct sunlight) with a pentacene-based sensitizer.

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Determination of ceiling temperature and thermodynamic properties of low ceiling temperature polyaldehydes

Cited by 21 publications

References 28 publications

Functionalized and Degradable Polyphthalaldehyde Derivatives

Functionalized and Degradable Polyphthalaldehyde Derivatives

Time‐delayed photo‐induced depolymerization of poly(phthalaldehyde) self‐immolative polymer via in situ formation of weak conjugate acid

Sunlight photodepolymerization of transient polymers

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