Tuning HS Release by Controlling Mobility in a Micelle Core.

Drug delivery from polymer micelles has been widely studied, but methods to precisely tune rates of drug release from micelles are limited. Here, the mobility of hydrophobic micelle cores was varied to tune the rate at which a covalently bound drug was released. This concept was applied to cysteine-triggered release of hydrogen sulfide (HS), a signaling gas with therapeutic potential.

Toughening Cellulose: Compatibilizing Polybutadiene and Cellulose Triacetate Blends.

We report the synthesis of an ABA triblock copolymer of the structure CTA--PB--CTA (CTA = cellulose triacetate and PB = polybutadiene) and its ability to compatibilize immiscible CTA/PB polymer blends. CTA--PB--CTA was synthesized via ring-opening metathesis polymerization of cyclooctadiene (COD) in the presence of CTA containing a single olefin on the reducing end. The ABA triblock copolymer was incorporated into CTA/PB blends, resulting in films that were clear, tough, and creaseable, and increases in modulus, elongation at break, and toughness were observed with addition of as little as 1 wt % compatibilizer.

Reversibly Cross-linkable Bottlebrush Polymers as Pressure-Sensitive Adhesives.

Dynamically cross-linkable bottlebrush polymer adhesives were synthesized by the grafting-from strategy through a combination of ring-opening metathesis polymerization (ROMP) and photoiniferter polymerization. A norbornene-containing trithiocarbonate was first polymerized by ROMP to form the bottlebrush polymer backbone; this was followed by blue-light-mediated photoiniferter polymerization of butyl acrylate initiated by the poly(trithiocarbonate) to form the bottlebrush polymer. This strategy afforded well-defined bottlebrush polymers with molar masses in excess of 11 000 kg/mol.

Tapered Bottlebrush Polymers: Cone-Shaped Nanostructures by Sequential Addition of Macromonomers.

Tapered (cone-shaped) bottlebrush polymers were synthesized for the first time by ring-opening metathesis polymerization (ROMP) using a sequential-addition of macromonomers (SAM) strategy. Polystyrene macromonomers with molecular weights that increased from 1 to 10 kg mol were polymerized in sequence to high conversion, yielding tapered bottlebrush polymers that could be visualized by atomic force microscopy (AFM).

Improving the Charge Conductance of Elemental Sulfur via Tandem Inverse Vulcanization and Electropolymerization.

The synthesis of polymeric materials using elemental sulfur (S) as the chemical feedstock has recently been developed using a process termed inverse vulcanization. The preparation of chemically stable sulfur copolymers was previously prepared by the inverse vulcanization of S and 1,3-diisopropenylbenzene (DIB); however, the development of synthetic methods to introduce new chemical functionality into this novel class of polymers remains an important challenge. In this report the introduction of polythiophene segments into poly(sulfur--1,3-diisopropenylbenzene) is achieved by the inverse vulcanization of S with a styrenic functional 3,4-propylenedioxythiophene (ProDOT-Sty) and DIB, followed by electropolymerization of ProDOT side chains.