In accordance with the present invention, there are provided
toughening agents which are useful for improving the performance properties of
epoxy-based
adhesive formulations. For example, epoxidized polysulfides have been found to be useful
toughening agents of component level underfill
adhesive compositions. Invention materials are liquid rubbers which provide improved
fracture toughness while maintaining satisfactory capillary flow properties. Invention materials can be synthesized in neat (solventless) reactions from readily available low-cost raw materials and isolated in high yields. They have linear and branched telechelic structures with terminal
epoxide functional groups, and are prepared without substantially increasing the molecular weight of the starting
polysulfide materials. Invention materials are compatible with common
epoxy formulations and may be used without purification. At low levels of incorporation, they provide adhesives that meet the minimum
fracture toughness (Gq>2.0 lb / in) and capillary flow specifications (
flow time<180 seconds) for many commercial underfill applications. In accordance with a further embodiment of the present invention, there are provided
adhesive compositions comprising invention compounds and methods for use thereof. In additional embodiments of the present invention, there are provided methods for the preparation of invention
toughening agents, methods for adhesively attaching a device to a substrate, and assemblies comprising first article(s) adhered to second article(s).