NEAR-IR FLUORESCENT LABELS FOR DETERMINATION OF FUNCTIONAL-GROUPS IN POLYMERIC MATERIALS

Cyanine-based near-i.r. fluorescent probes have been applied as labels to determine functional groups in polymeric materials. The advantage of such probes is that they can be applied to polymers which are autof luorescent or strongly coloured or to strongly scattering polymer emul sions. Two examples are discussed: the labelling of a polymer latex wi th aldehyde functional groups, by application of a cyanine with a hydr azide functionality, and the labelling of amino functional groups in a polyamide utilizing a cyanine label with an isothiocyanate functional ity. The cyanines which have been applied absorb and fluoresce in the 650-700 nm range and in the 750-800 nm range, respectively. In additio n to near-i.r. fluorescence, the cyanine dyes have strong absorption ( with extinction coefficients in the order of 2 x 10(5) l mol(-1)cm(-1) ). It is shown that by application of reflection absorption measuremen ts also sensitive detection of labelled functional groups can be reali zed. The combined application of fluorescence and reflection measureme nts allows for the detection of concentration and distribution of func tional groups in polymeric systems down to very low levels. (C) 1997 E lsevier Science Ltd.