In further work investigating the intriguing application of diacetylene copolymers in fingermark detection, methods were developed to control (inhibit or enhance) the diacetylene polymerization reaction in fingermarks treated with a mixture of the monomers 2,4-hexadiyne-1,6-bis-(phenylurethane) (HDDPU) and 2,4-hexadiyne-1,6-bis(p-chlorophenylurethane) (HDDCPU) in acetone solution. These methods included the use of a humidity chamber to reduce the amount of background development while promoting development on the fingermark, subjecting developed fingermarks to freezing temperatures and using a solvent to remove unreacted monomer in order to inhibit the polymerization reaction. Developed fingermarks were enhanced by conventional lighting (white light, filtered light) and fast Raman mapping, which was shown to be advantageous over FTIR imaging. This study also demonstrated the applicability of diacetylene copolymer solutions in the covert detection of fingermarks on difficult surfaces. Furthermore, fingermarks were successfully developed with good ridge detail on pig skin (used as a model for human skin, a notoriously difficult surface on which to develop fingermarks).
Keywords: Raman mapping; diacetylenes; fingermarks; forensic science; solid-state polymerization; topochemical polymerization.
© 2014 American Academy of Forensic Sciences.