Reactive blending approach to modify spin coated epoxy film

Markus P.K. Turunen, Tomi Laurila, Kimmo Solehmainen, Jorma K. Kivilahti

Research output: Book/ReportReport


Epoxies find wide use in electronics manufacturing, but their applicability is often limited by their inherent brittleness. In this study, epoxy resin, SU8, was modified through reactive blending to enhance both its surface and bulk properties. For the purpose, novel star-shaped poly(e-caprolactone) (PCL) oligomers were synthesized and functionalized to enable crosslinking reaction between epoxy and oligomer. Thorough characterization of the oligomers confirmed that their structure could be tailored in a controlled manner by adjustment of the ratio of initiator to monomer(s) in the feed. Effective modification of the epoxy with the oligomer demands that a high degree of crosslinking be achieved. To ensure this, a dual-catalyzed crosslinking reaction was utilized and investigated by the model-free reaction kinetics evaluation method. The crosslinking conditions were optimized to allow the incorporation of a large amount of oligomer into the epoxy while minimizing the reaction induced phase separation. The modified material was then used to prepare films in the thickness range of a few micrometers. Thermal properties of such films are difficult to determine but need to be known for the assessment of interfacial compatibility. Spectrophotometry with a temperature option was employed in a novel way to provide information about the thermal properties of films. The thermal properties were inferred from the optical characterization data. When the aim of the manufacturing is bioadaptive devices, especially in implanted devices, the properties of surfaces and biocompatibility become important. Contact angle measurements were carried out to follow the effect of reactive blending on the surface free energy of the films, and it was discovered that the hydrophobicity is slightly increased. The morphology of seeded endothelial cells indicated biocompatibility.
Original languageEnglish
Place of PublicationEspoo
PublisherHelsinki University of Technology
Number of pages42
ISBN (Print)951-22-7036-6
Publication statusPublished - 2004
MoE publication typeD4 Published development or research report or study

Publication series

SeriesHelsinki University of Technology: Department of Electrical and Communications Engineering: Laboratory of Electronics Production Technology. Report series


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