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Todd Emrick

Publications and source records attributed to Todd Emrick.

23 records · Page 2Linked to original sources
PubMed2003

Ultrathin cross-linked nanoparticle membranes.

The fabrication of functional nanostructured materials for sensing, encapsulation and delivery requires practical approaches to self-assembly on multiple length scales and the synthesis of tough yet permeable structures. Here, the self-assembly of functionalized, photoluminescent nanoparticles at liquid interfaces, followed by cross-linking of the associated ligands, affords robust membranes that maintain their integrity even when they are removed from the interface. These composite membranes, nanometers in thickness, are elastic yet permeable and have potential applications involving controlled permeability and diffusion. Cadmium selenide (CdSe) nanoparticles are used, since their inherent photoluminescence offers a direct way to probe the spatial organization of the particles. Functionalized ligands attached to the nanoparticles provide an effective means to stabilize the interfacial assembly by cross-linking. The concepts shown are adaptable to other type of nanoparticles, ligands, and solvent combinations.

Colloids↗
PubMed2003

Novel polymer capsules from amphiphilic graft copolymers and cross-metathesis.

We report the synthesis of polymer capsules from amphiphilic graft copolymers composed of reactive, hydrophobic polyolefin backbones and hydrophilic poly(ethylene glycol) (PEG) grafts. The capsules are produced by self-assembly of the polymers at the oil-water interface, followed by cross-linking with bis-cyclooctene PEG derivatives. The fluorescence of these capsules results from integration of rhodamine B functionalized cyclooctene 1 into the polymer structure. The use of the graft copolymer architecture in capsule synthesis provides significant opportunities to tune both the surface properties, in terms of recognition, and the membrane properties, in terms of mechanical strength, encapsulation, and release.

Journal Article↗
PubMed2002

Preparation of cadmium selenide-polyolefin composites from functional phosphine oxides and ruthenium-based metathesis.

Cadmium selenide nanoparticles, prepared by known methods, were stabilized with functional phosphine oxide 1, then used to support the polymerization of cyclic olefins radially outward from the surface by ruthenium-catalyzed ring-opening metathesis polymerization (ROMP). The conversion of compound 1 into the new metathesis catalyst 3 by carbene exchange and the subsequent polymerization of cyclic olefins were observed spectroscopically by (1)H NMR to afford for example CdSe-polycyclooctene composite 6. Transmission electron micrographs on thin films of these composites showed good nanoparticle dispersion. This is in stark contrast to the substantial nanoparticle aggregation observed when similar polymerizations were performed in the presence of conventional TOPO-covered nanoparticles. The methods reported here to prepare composite product 6 are applicable to other cyclic olefins, and suggest that this chemistry will be useful for incorporating CdSe nanoparticles into a wide variety of polymer matrices.

Alkenes↗
PubMedDate not supplied

Soluble camptothecin derivatives prepared by click cycloaddition chemistry on functional aliphatic polyesters.

Aliphatic polyesters are of interest as biomaterials and drug-delivery vehicles, as their ability to degrade under physiological conditions provides a mechanism for both drug release and clearance of the polymer from the body. Presented here is the synthesis of a polyester-drug graft copolymer conjugate, enabled by click cycloaddition of azide-functionalized camptothecin derivatives with alkyne-functionalized aliphatic polyesters. Further grafting of residual alkyne groups with azide-terminated poly(ethylene oxide) gave a water-soluble polyester-camptothecin conjugate. Control over PEGylation and drug loading, inherent to the graft copolymer design, opens versatile routes to new materials with potential utility in polymer therapeutics.

Azides↗