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Polymerization-induced self-assembly (PISA) is leveraged for the synthesis of ultra-high molecular weight polymers in concentrated but free-flowing dispersions. 

Wavelength-dependent photoreactions present an opportunity to achieve chemoselectivity of functional groups that otherwise demonstrate similar reactivity under traditional thermal conditions. 

Abstract We describe a methodology of post‐polymerization functionalization to enable subsequent bulk depolymerization to monomer by utilizing mechanochemical macro‐radical generation. By harnessing ultrasonic chain‐scission in the presence ofN‐hydroxyphthalimide methacrylate (PhthMA), we successfully chain‐end functionalize polymers to promote subsequent depolymerization in bulk, achieving up to 82 % depolymerization of poly(methyl methacrylate) (PMMA) and poly(α‐methylstyrene) (PAMS) within 30 min. This method of depolymerization yields a high‐purity monomer that can be repolymerized. Moreover, as compared to the most common methods of depolymerization, this work is most efficient with ultra‐high molecular weight (UHMW) polymers, establishing a method with the potential to address highly persistent, non‐degradable all‐carbon backbone plastic materials. Lastly, we demonstrate the expansion of this depolymerization method to commercial cell cast PMMA, achieving high degrees of depolymerization from post‐consumer waste. This work is the first demonstration of applying PhthMA‐promoted depolymerization strategies in homopolymer PMMA and PAMS prepared by conventional polymerization methods. 

We investigate a new series of precise ion-containing polyamide sulfonates (PAS x Li), where a short polar block precisely alternates with a non-polar block of aliphatic carbons ( x = 4, 5, 10, or 16) to form an alternating (AB) n multiblock architecture. The polar block includes a lithiated phenyl sulfonate in the polymer backbone. These PAS x Li polymers were synthesized via polycondensation of diaminobenzenesulfonic acid and alkyl diacids (or alkyl diacyl chlorides) with x -carbons, containing amide bonds at the block linkages. The para - and meta -substituted diaminobenzene monomers led to polymer analogs denoted p PAS x Li and m PAS x Li, respectively. When x ≤ 10, the para -substituted diamine monomer yields multiblock copolymers of a higher degree of polymerization than the meta -substituted isomer, due to the greater electron-withdrawing effect of the meta -substituted monomer. The PAS x Li polymers exhibit excellent thermal stability with less than 5% mass loss at 300 °C and the glass transition temperatures ( T g ) decrease with increasing hydrocarbon block length ( x ). Using the random phase approximation, the Flory–Huggins interaction parameter ( χ ) is determined for p PAS10Li, and χ (260 °C) ∼ 2.92 reveals high incompatibility between the polar ionic and non-polar hydrocarbon blocks. The polymer with the longest hydrocarbon block, p PAS16Li, is semicrystalline and forms well-defined nanoscale layers with a spacing of ∼2.7 nm. Relative to previously studied polyester multiblock copolymers, the amide groups and aromatic rings permit the nanoscale layers to persist up to 250 °C and thus increase the stability range for ordered morphologies in precise ion-containing multiblock copolymers. 

We introduce a novel synthetic strategy in which high molecular weight comb copolymers with aliphatic side chains can collapse into single-chain nanoparticles (SNCPs) via photodimerization of anthracene under ultraviolet (UV) irradiation. By deliberately selecting hydrophobic comonomers with disparate solvency, we demonstrated that we could control chain collapse. We attribute these results to the formation of pseudo-unimicellar structures, whereby polyisobutylene (PIB) side chains are preferentially solvated, thereby compressing anthracene moieties to form a denser crosslinked core. The control of hydrophobic interactions is a common occurrence in proteins and we believe that our approach can be further extended to achieve multi-compartment SCNPs whereby each section is responsible for a given function.