Photo-controlled atom transfer radical polymerization (PhotoATRP) was implemented, for the first time, to accomplish polymerization induced self-assembly (PISA) mediated by UV light (λ = 365 nm) using ppm levels (ca. < 20 ppm) of copper catalyst at ambient temperature. Using CuII Br 2 /tris(pyridin-2-ylmethyl)amine (TPMA) catalyst systems, PISA was per-formed all in one-pot starting from synthesis of solvophilic poly(oligo(ethylene oxide) methyl ether methacrylate) (POEGMA) blocks to core-crosslinked nanoparticles (NPs) utilizing poly(glycidyl methacrylate) (PGMA) and N,N-cystamine bismethacrylamide (CBMA) as the solvophobic copolymer and crosslinking agent, respectively. Sequential chain-extensions were performed for PGMA demonstrating capabilities for accessing multi-block copolymers with temporal control via switching the UV light on and off. Further, core-crosslinking of PISA nanoparticles was performed via the slow incorporation of the CBMA enabling one-pot crosslinking during the PISA process. Finally, the disulfide installed in the CBMA core-crosslinks allowed for the stimuli-triggered dissociation of nanoparticles using DL-dithiothreitol at acidic pH. File list (2)download file view on ChemRxiv One-pot PhotoATR-PISA_Macromolecules_Final.docx (2.88 MiB) download file view on ChemRxiv Supporting Information_PhotoATR-PISA _Macromolecule...

In this review, we detail the progress throughout the years toward developing truly orthogonal polymerization mechanisms and modification procedures en route to complex macromolecular structures built from synthetic polymer materials. The orthogonal modifications of polymer side‐chains and end‐groups via sequential click reactions is described providing post‐polymerization routes to functional materials and unique polymer topologies. Further, historical and modern orthogonal polymerization methodologies are thoroughly reviewed showing the evolution of the field through the decades long study of selective polymerization mechanisms that provide unique copolymer structures that are typically difficult to achieve. These include the combinations of reversible deactivation radical polymerization mechanisms with a variety of polymerization mechanisms including ring opening polymerizations, ring opening metathesis polymerizations, and cationic polymerizations, to name a few.

Photocontrolled atom transfer radical polymerization-induced self-assembly (PhotoATR-PISA) mediated by UV light (λ = 365 nm) was utilized to obtain polymer nanostructures with variable morphologies, including nanospheres, wormlike micelles, and vesicles, at ambient temperature by using parts per million (ppm) levels (ca. < 20 ppm) of copper catalyst. Using Cu­(II)­Br2/tris­(pyridin-2-ylmethyl)­amine (TPMA) catalyst systems and functional ATRP initiators, we performed PhotoATR-PISA all in one-pot via sequential chain extension starting from solvophilic poly­(oligo­(ethylene glycol) methyl ether methacrylate) (POEGMA) macroinitiator growth followed by PISA using different proportions of glycidyl methacrylate (GMA) and/or benzyl methacrylate (BMA) core-forming blocks forming alkyne-functional polymer nanoparticles. Remarkably, multiple, iterative chain extensions were accomplished introducing additional GMA and BMA monomers in multiple steps without additional solvent leading to stable nanoparticle dispersions with record-high final solid concentrations of 63 and 79 wt %, respectively. Core cross-linked nanoparticles (CCL NPs) were synthesized by incorporating N,N-cystamine bismethacrylamide (CBMA) cross-linkers in later stage chain extensions providing a route to CCL nanoworms. Furthermore, introducing BMA and GMA in varying orders sequentially allowed for the synthesis of sequence-controlled gradient copolymers, though this had limited effects on nanoparticle morphology. Finally, utilizing the copper­(I)-catalyzed azide–alkyne cycloaddition (CuAAC) click reactions between alkyne-functionalized NPs and bisazide, telechelic poly­(ethylene glycol) (PEG), nanostructured networks were fabricated consisting of nanospherical, beaded worm, nanoworm, and vesicle morphologies. The interstitial porosity of these ClickNP networks allows them to be potent adsorbents with explored applications in water treatment demonstrated via the rapid uptake of phenanthrene pollutants from aqueous solutions.

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A new trehalose-grafted poly(2-hydroxyethyl methacrylate) (HEMA) glycopolymer was synthesized via the perfluorophenyl azide (PFPA)-mediated Staudinger reaction between poly(HEMA-co-HEMA-PFPA) and a diphenylphosphine-derivatized trehalose. The reaction occurred rapidly at room temperature without the use of any catalyst, giving the trehalose glycopolymers over 68% yield after 1 h. The grafting density of trehalose can be controlled by the copolymer composition in poly(HEMA-co-HEMA-PFPA), resulting in 6.1% (TP1) or 37% (TP2) at 10:1 and 1:1 HEMA/HEMA-PFPA feed ratio, respectively. The trehalose glycopolymer was covalently attached on glass slides or silicon wafers using a thin film of poly(HEMA-co-HEMA-PFPA) as the adhesion layer, achieved through the C−H insertion reaction of the photogenerated singlet perfluorophenyl nitrene. To demonstrate the ability of the trehalose glycopolymer to capture mycobacteria, arrays of the trehalose glycopolymer were fabricated and treated with Mycobacterium smegmatis. Results from the optical, fluorescence, and scanning electron microscopy showed that mycobacteria were indeed captured on the trehalose glycopolymer. The amount of mycobacteria captured increased with the percent trehalose in the trehalose glycopolymer and also with the concentration of the trehalose glycopolymer. In addition, the captured bacteria could be visualized by the naked eye under the illumination of a hand-held UV lamp.

Organophosphorous-based nerve agents remain one of the most toxic and accessible chemical warfare agents known to man. Herein, we report the development of novel, oxime-functionalized poly(4-vinylpyridine) (P4VP-Ox) materials as inexpensive, scalable polymeric substrates capable of rapid decontamination of nerve agents, as demonstrated using one nerve agent simulant, dimethyl-4-nitrophenyl phosphate (DMNP). The incorporated oximes adjacent to positively charged pyridinium salts remain deprotonated at neutral to slightly basic pH, providing super-nucleophilic materials to deactivate nerve agents and their simulants rapidly and irreversibly. These materials were electrospun to form nanofabrics, providing increased surface area and enhanced reactivity for degradation of DMNP. Nanofibers obtained from P4VP functionalized at 20 mol % pendants with ortho-pyridinium oximes moieties (P4VP-OOx20%) provided the fastest reaction kinetics. This substrate provided complete decomposition of DMNP within 1.5 h and calculated t 1/2 = 14.4 min. The P4VP-Ox substrates were also found to be recyclable, allowing for quantitative DMNP degradation within 8 h over the course of four reaction cycles. Furthermore, to mimic real-life scenarios, we attempted solid-state DMNP degradation via applying small drops of DMNP directly on the nanofabric substrates and extracting with water for 31P NMR analysis. Overall, the P4VP-OOx20% substrate was found to retain its reactivity in the solid state, with the as-prepared nanofabric displaying >95% DMNP degradation after 6 h. When performed in different environments (i.e., 100% humidity, hexanes-rich atmosphere), the reactivity diminished slightly but still displayed >95% degradation after 24 h of reaction, establishing these materials for applications as reactive, economical, and easily scalable Chem-Bio protective materials.

Direct write printing is restricted by the lack of dielectric materials that can be printed with high resolution and offer dissipation factors at radio frequency (RF) within the range of commercial RF laminates. Herein, we outline the development of dielectric materials with dielectric loss below 0.006 in X and Ku frequency bands (8.2−18 GHz), the range required for radio frequency and microwave applications. The described materials were designed for printability and processability, specifically a prolonged viscosity below 1000 cps and a robust cure procedure, which requires minimal heat treatment. In the first stage of this work, nonpolar ring-opening metathesis polymerization (ROMP) is demonstrated at room temperature in an open-air environment with a low-viscosity monomer, 5-vinyl-2-norbornene, using the second-generation Grubbs catalyst (G-II). Differential scanning calorimetry (DSC) was used to study how the catalyst activity is increased with heating at various stages in the reaction, which is then used as a strategy to cure the material after printing. The resulting cured poly(5-vinyl-2-norbornene) material is then characterized for dielectric and mechanical performance before and after a secondary heat treatment, which mimics processing procedures to incorporate subsequent printed conductor layers for multilayer applications. After the secondary heat treatment, the material exhibits a 55.0% reduction in the coefficient of thermal expansion (CTE), an increase in glass-transition temperature (T g ) from 32.4 to 46.1 °C, and an increased 25 °C storage modulus from 428 to 1031 MPa while demonstrating a minimal change in dielectric loss. Lastly, samples of the developed dielectric material are printed with silver overtop to demonstrate how the material can be effectively incorporated into fully printed, multilayer RF applications.

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