Polymer supports in organic catalysis and synthesis.

Recent developments in the preparation of polymer supports for synthesis and catalysis are reviewed. The use of insoluble supports for synthesis of one molecule per bead and chemistry leading to new ways to use insoluble supports are discussed. New routes to design soluble, high capacity supports for synthesis are highlighted and the roles of polymers in catalysis, both for re-use and separation, are discussed using metathesis catalysts and Pd(0) catalysts as examples. The role of dendrimers as supports for synthesis and catalysis are reviewed, and new separation schemes using inverse temperature-dependent solubility of polymers and liquid/liquid separations are discussed.

Functionalized hyperbranched polyethylene powder supports.

[reaction: see text] Polyethylene powders with useful loadings of functional groups are accessible by hyperbranched grafting chemistry. Using a 200 microm diameter high-density powder, loadings of up to 0.4 mmol/g of CO(2)H groups are attained. The carboxylic acid groups in the resulting powders can be further functionalized covalently or ionically and resulting powders have the physical durability and solvent resistance associated with polyethylene itself.

Fluorous-phase soluble polymeric supports.

Fluorous phase soluble polymer supports derived from fluoroacrylate polymers are described. N-Acryloxysuccinimide-containing fluoroacrylate polymers were readily prepared from commercially available monomers. The activated acrylates so prepared were then converted into chelating and non-chelating ligands by amidation of the N-acryloxysuccinimide active ester residues. Phosphine ligands attached to these supports were used to prepare neutral and cationic rhodium(I) hydrogenation catalysts as well as palladium(0) catalysts. Similar substitution of pendant active ester groups to form hydroxamic acid ligands for metal sequestration is also feasible. Liquid/liquid extraction readily separated, recycled and reused these polymer-bound ligands and catalysts. While fluorous phase solubility could be attained with polymers containing only heptafluorobutyryl groups, selective solubility in a fluorous phase in contact with an organic phase was only seen with fluoroacrylates that contained larger fluorinated ester groups.

Alternative polymer supports for organic chemistry.

The use of polymers other than divinylbenzene crosslinked polystyrene as supports in organic chemistry is discussed. Insoluble polymer alternatives to DVB crosslinked polystyrene discussed include porous polyethylene supports, polymer-supported functional colloids, micron and submicron-sized particles and hollow spheres and one-dimensional supports. Soluble polymers including polyethylene, poly(alkene oxide)s, polyacrylamides, and fluorinated acrylates are discussed along with thermomorphic strategies where liquid-liquid separation of a biphasic systems is used as a way to effect polymer recovery in systems that are monophasic on heating.

Electrostatic immobilization of glucose oxidase in a weak acid, polyelectrolyte hyperbranched ultrathin film on gold: fabrication, characterization, and enzymatic activity.

In this paper we show that hyperbranched polymers can be used as a host matrix for electrostatic entrapment of enzymes. Specifically, amine-functionalized glucose oxidase (GOx+) and horseradish peroxidase, as well as poly(amidoamine) dendrimer-modified horseradish peroxidase, reversibly sorb into polyanionic, hyperbranched poly(sodium acrylate) (PAA-) films that are on the order of a few hundred angstroms thick. The quantity of GOx+ entrapped within the PAA- films depends on the nature of film preparation but is typically on the order of 0.06 unit/cm2. The extent to which entrapped GOx+ retains its activity depends on the film history, but for PAA-/GOx+ composites not exposed to glucose and stored at 4 degrees C, the original activity is retained for up to 68 days and perhaps longer.

Applications of polymeric smart materials to environmental problems.

New methods for the reduction and remediation of hazardous wastes like carcinogenic organic solvents, toxic materials, and nuclear contamination are vital to environmental health. Procedures for effective waste reduction, detection, and removal are important components of any such methods. Toward this end, polymeric smart materials are finding useful applications. Polymer-bound smart catalysts are useful in waste minimization, catalyst recovery, and catalyst reuse. Polymeric smart coatings have been developed that are capable of both detecting and removing hazardous nuclear contaminants. Such applications of smart materials involving catalysis chemistry, sensor chemistry, and chemistry relevant to decontamination methodology are especially applicable to environmental problems.