Fréchet’s early work focused on polymer-supported chemistry with the first approach to the solid-phase synthesis of oligosaccharides  and pioneering work on polymeric reagents and polymer protecting groups. In 1979 Working with C.G. Willson at IBM during a sabbatical leave, he invented chemically amplified photoresists  for micro and nanofabrication. This widely used patented technology  which enables the extreme miniaturization of microelectronic devices is now ubiquitous for the fabrication of the very powerful computing and communication equipment in worldwide use. The addition of photogenerated bases  led to additional advances in chemically amplified resists.  In 1990 working with Craig Hawker at Cornell, he developed the convergent synthesis of dendrimers  as well as approaches to hyperbranched polymers. In 1992, working with F. Svec at Cornell, he reported the first preparation of macroporous polymer monoliths  that are now used in a variety of chemical separations.  Later work at Berkeley saw the development of polymers and dendrimers as carriers for targeted therapeutics  and successful approaches to new organic materials for transistors and solar cells.