Confocal Raman study of poly(ethylene terephthalate) fibres dyed in supercritical carbon dioxide: dye diffusion and polymer morphology

Dye Diffusion in Polymer Films Subjected to Supercritical CO2: Confocal Raman Microscopy and Modelling

“…When focussing the laser energy onto the surface of the sample, rather than beneath its surface, the high lateral spatial resolution (1-2 mm) of the system may be exploited and hence mapping of the sample cross section provides reference data to assess the confocality achieved when operating in confocal mode with the oil immersion objective. A comparison of the confocal data with data measured along the cross section of a microtomed film sample (as shown in our earlier publications [12,13,31] ) indicates that the accuracy of the CRM data obtained with an oil immersion objective is limited to a depth of ca. 70 mm.…”

“…These complications have been observed for other examples of CRM studies of PET dyed from a supercritical solution. [13,31] Nevertheless, despite the inaccuracy of the oil immersion data at depths greater than ca. 70 mm, accurate information may be generated from shallower depths, giving us confidence in using the raw confocal data to model the diffusion mechanism under supercritical conditions.…”

“…CRM has recently been applied to investigate the diffusion in a dynamic system, [30] where the spectral response of a model drug in a polymer membrane was studied as a function of the Raman measurement depth and diffusion time. In our recent related study, [31] the feasibility of using CRM was demonstrated in applications for PET fibres processed under conditions relevant to the textile industry.…”

Confocal Raman Microscopy: Performance, Pitfalls, and Best Practice

“…Numerous workers have confirmed the benefits of using immersion objectives to depth profile complicated materials ranging from polymers and paper products to human skin. [29][30][31][32][33][34][35][36][37][38][39][40] As well as reducing the depth-scale compression, the oil has an additional beneficial effect of wetting out particle/air boundaries in porous, highly scattering particulate coatings, improving transparency and permitting confocal profiling of samples that would be opaque to a dry objective. 28 Nonetheless, a significant mismatch between the index of the coupling oil and the sample will result in a slight axial shift and distortion in the shape of individual layers, manifested by an attenuation that increases with depth.…”

“Special Issue—Supercritical Fluids” Literatures on Dyeing Technique of Supercritical Fluid Carbon Dioxide

“…In 2005, Kazarian [72] used Raman infrared spectrometer to observe the diffusion behavior of C.I. Disperse Yellow 23 dye in PET fiber.…”