Depolymerizable polymers are stimuli-responsive materials triggered to depolymerize rapidly and completely into their constituent monomers on command. Applications include triggerable vehicles for ...controlled release, restructurable materials, disappearing or sacrificial composites, and lithographic resists. Owing to their widespread utility, significant efforts have aimed to prepare and explore depolymerizable polymers and their corresponding triggers. This “Prospective” highlights advances since their discovery over a half-century ago, discusses methods in their preparation, and presents recent developments in triggered depolymerization. It also surveys applications that harness these polymers’ unique properties, while offering insights into research directions that may contribute to progress in this dynamic field.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Photo-directed orientation control of block copolymer (BCP) domains is a powerful method for generating distinct regions of perpendicular and parallel-aligned lamella in a single film layer. In this ...study we demonstrate the versatility of aromatic methacrylate polymer films for tuning the wetting behaviour of PS-
b
-PMMA films on UV exposure. Poly(aryl methacrylate) films with excellent thermal and solvent stability were obtained by thermal crosslinking of spin-coated films. Upon exposure to UV light (254 nm), the surface polarity of the films changed as a result of the photo-Fries rearrangement of the aromatic ester groups. Following UV exposure to appropriate doses, the irradiated poly(aryl methacrylate) films can induce a change in the orientation of the domains of an overlayer of PS-
b
-PMMA from parallel to perpendicular lamellar structures. Patterning with a photomask enables generation of high fidelity BCP microdomain regions with targeted orientation. It is worth noting that the UV dose required to induce lamellar orientation in a wide range of BCP films can be tailored by rational selection of the poly(aryl methacrylate), suggesting outstanding flexibility in controlling BCP wetting behaviour. This simple, rapid, cost-effective and flexible approach to controlling BCP orientation makes poly(aryl methacrylate)s extremely promising for block copolymer self-assembly applications.
UV irradiated poly(aryl methacrylate) films can induce a change in the orientation of the domains of an overlayer of PS-
b
-PMMA from parallel to perpendicular lamellar structures.
Incorporation of supramolecular cross-linking motifs into low-ceiling temperature ( T c ) polymers allows for the possibility of remendable polymeric networks and nanoparticles whose structure and ...chemical backbones can be dynamically modified or depolymerized as desired. Herein, we demonstrate the synthesis of phthalaldehyde–benzaldehyde copolymers bearing a pendant dimerizing 2-ureido-pyrimidinone (UPy) motif. The UPy moiety promotes single-chain polymeric nanoparticle formation through non-covalent cross-linking at intermediate concentrations and results in reversible polymer network formation at high concentrations. Furthermore, due to the low T c polymer backbone within such macromolecules, the materials depolymerize to monomer under appropriate conditions. We envision that the synthesis of such depolymerizable, adaptive supramolecular polymeric materials may find use in materials capable of self-healing and remodeling as well as in triggered release applications or the development of nanoporous structures.
Thermally triggerable polymer films that degrade at modest temperatures (≈85 °C) are created from a blend of cyclic polyphthalaldehyde (cPPA) and a polymeric thermoacid generator, poly(vinyl ...tert‐butyl carbonate sulfone) (PVtBCS). PVtBCS depolymerizes when heated, generating acid which initiates the depolymerization of cPPA into volatile byproducts. The mass loss onset for 2 wt% PVtBCS/cPPA is 22 °C lower than the onset for neat cPPA alone in dynamic thermogravimetric analysis experiments. Increased concentrations of PVtBCS increase the rate of depolymerization of cPPA. Raman spectroscopy reveals that the monomer, o‐phthalaldehyde, is the main depolymerization product of the acid‐catalyzed depolymerization of cPPA. The PVtBCS/cPPA blend is a promising material for the design and manufacture of transient electronic packaging and polymers.
A thermally triggered transient material is presented that depolymerizes to volatile products, leaving less than 2 wt% of residuals. Poly(vinyl t‐butyl carbonate sulfone) is shown to be an effective thermoacid generator and thermal depolymerization trigger for poly(phthalaldehyde) films, lowering its thermal depolymerization temperature and increasing its depolymerization rate. The reported polymer blend enables rapidly vanishing polymer films at moderate temperatures.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Block copolymer (BCP) self-assembly has emerged over the past two decades as a promising method for generation of features for manufacture of integrated circuits and memory devices. ...Low-molecular-weight BCPs with blocks that are highly immiscible can generate features of dimensions below 10 nm. However, it is often challenging to select a common good solvent for high-χ BCPs to allow spin coating. In addition, controlling the alignment of phase separated morphologies with respect to the wafer and at the air interface may be challenging. Here, we prepare a series BCPs of polystyrene (PS) and poly-6-O-methacryloyl-d-galactopyranose (PMAGal), where the polar galactose has been protected with more hydrophobic acetonides. The acetonide protecting groups could be deprotected with trifluoroacetic acid to yield the more polar galactose repeat units to increase the incompatibility of the sugar-containing block with the PS blocks. The bulk morphology of the protected and deprotected versions was studied using small-angle X-ray scattering, where the morphology could be switched from disordered for the protected BCP to either cylindrical or lamellar for the deprotected version or between two ordered phases. Finally, we demonstrate phase separation on the wafer via solvent vapor annealing with H2O/THF, resulting in lamellar patterning with domains as small as 14 nm.
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IJS, KILJ, NUK, PNG, UL, UM
The conductive polymer precursor, 3-hexylthiophene (3-HT), is successfully encapsulated in ca. 5 μm polyamide microcapsules by interfacial polymerization. The microcapsules are thermally stable up to ...300°C, and electrochemically stable in a Li-ion battery electrolyte. Mechanical rupture of the microcapsules releases the liquid core and electropolymerization of the 3-HT monomer was analyzed using cyclic voltammetry. Scanning electron microscopy and vibrational (Raman) spectroscopy confirm the presence of newly formed poly(3-HT) thin films on model electrode surfaces. Encapsulation of battery additives such as 3-HT in microcapsules that remain latent and stable in the electrolyte until required may lead to enhanced battery performance and extended battery lifetimes.
Thermally triggered degradation of transient electronics is accomplished by S.R. White and co‐workers using protective wax coatings that melt and release encapsulated acid microdroplets, as described ...on page 3783. A self‐destructive device is shown, where heat triggering is remotely controlled. The heater of the device is wirelessly powered through inductive coupling, and subsequent melting of the wax then leads to rapid device destruction via acidic degradation of the electronic components.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Incorporation of supramolecular cross-linking motifs into low-ceiling temperature (
T
c
) polymers allows for the possibility of remendable polymeric networks and nanoparticles whose structure and ...chemical backbones can be dynamically modified or depolymerized as desired. Herein, we demonstrate the synthesis of phthalaldehyde-benzaldehyde copolymers bearing a pendant dimerizing 2-ureido-pyrimidinone (UPy) motif. The UPy moiety promotes single-chain polymeric nanoparticle formation through non-covalent cross-linking at intermediate concentrations and results in reversible polymer network formation at high concentrations. Furthermore, due to the low
T
c
polymer backbone within such macromolecules, the materials depolymerize to monomer under appropriate conditions. We envision that the synthesis of such depolymerizable, adaptive supramolecular polymeric materials may find use in materials capable of self-healing and remodeling as well as in triggered release applications or the development of nanoporous structures.
Depolymerizable polymers are appended with supramolecular cross-linking motifs to enable preparation of tunable single-chain polymeric nanoparticles and degradable polymer networks.
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