Eric F. Connor

New Paradigms for Organic Catalysts: The First Organocatalytic Living Polymerization

A metal-free approach to the living ring-opening polymerization (ROP, shown schematically) of lactide has been developed using strongly basic amines such as 4-(dimethylamino)pyridine as transesterification catalysts. These organic catalysts must be used in combination with a nucleophile such as an alcohol, which is the actual initiating species.

Application of Complex Macromolecular Architectures for Advanced Microelectronic Materials

The distinctive features of well-defined, three-dimensional macromolecules with topologies designed to enhance solubility and amplify end-group functionality facilitated nanophase morphologies in mixtures with organosilicates and ultimately nanoporous organosilicate networks. Novel macromolecular architectures including dendritic and star-shaped polymers and organic nanoparticles were prepared by a modular approach from several libraries of building blocks including various generations of dendritic initiators and dendrons, selectively placed to amplify functionality and/or arm number, coupled with living polymerization techniques. Mixtures of an organosilicate and the macromolecular template were deposited, cured, and the phase separation of the organic component, organized the vitrifying organosilicate into nanostructures. Removal of the sacrificial macromolecular template, also denoted as porogen, by thermolysis, yielded the desired nanoporous organosilicate, and the size scale of phase separation was strongly dependent on the chain topology. These materials were designed for use as interlayer, ultra-low dielectric insulators for on-chip applications with dielectric constant values as low as 1.5. The porogen design, chemistry and role of polymer architecture on hybrid and pore morphology will be emphasized.

Synthesis of neutral nickel catalysts for ethylene polymerization ? the influence of ligand size on catalyst stabilityElectronic supplementary information (ESI) available: experimental protocol for (tmeda)Ni(Me)2 and compounds 3,4,7,8,9 and 10 and 1H-NMR magnetization transfer data for compound 7. See http://www.rsc.org/suppdata/cc/b3/b306701g/

A facile synthesis of nickel salicylaldimine complexes with labile dissociating ligands is described. In addition to producing highly active ethylene polymerization catalysts, important insights into the effect of ligand size on catalyst stability and information on the mechanism of polymerization are provided.

Versatile synthesis of nanometer sized hollow silica spheres

Using the controlled precipitation of silicic acid on functionalized polystyrene latexes, nanometer sized silica-coated spheres could be prepared and subsequently modified to allow dispersion in non-aqueous solvents; removal of the interior polymer by calcination resulted in the formation of hollow silica spheres.

Organocatalytic chain scission of poly(lactides): a general route to controlled molecular weight, functionality and macromolecular architecture

A facile, single-step transesterification approach to poly(lactides) with controlled molecular weights and end-group functionality, as well as block and star-shaped architectures is described using nucleophilic amine catalysts.

193-nm negative resist based on acid-catalyzed elimination of polar molecules

Development of 193-nm negative resists that meet the stringent performance requirements of sub-100 nm resolution with conventional 0.26 N TMAH developer has proven to be a significant challenge. Most of the systems that are currently under development are based on cross-linking mechanisms. They commonly suffer from image distortion caused by micro-bridging. An alternative approach is to look at polarity switch mechanisms. We have investigated the acid-catalyzed elimination of polar molecules as one such mechanism which may provide a pathway to develop negative resists that do not suffer from micro-bridging.

Organic Catalysis: A New and Broadly Useful Strategy for Living Polymerization

Significant effort has gone into the development of biodegradable polymers over the past few decades with the purpose of designing resorbable biomaterials, and, more recently, for designing commodity thermoplastics from renewable resources. Aliphatic polyesters, particularly polylactide, combine biocompatibility and biodegradability with remarkable physical properties and have the requisite thermal stability at processing temperatures. One of the most common synthetic routes to polyesters uses transition metal initiation compounds to affect the ring-opening polymerization (ROP) of the cyclic ester monomer. Advances in organometallic chemistry in the design and synthesis of single-site metal catalysts for ROP techniques1 has enabled the preparation of well-defined functional polymeric materials with predictable molecular weights, narrow polydispersities, architectural and stereochemical control. The ring-opening (ROP) polymerization of lactide has been accomplished from a variety of metal catalysts including aluminium, tin, zinc and yttrium through a coordination-insertion mechanism.2 Removal of the metal contaminant, bound to the chain-end, must be considered for many applications.