Search

Fast scanning chip calorimetry was used to perform an elaborate isothermal study of poly(3‐hexyl thiophene)/[6,6]‐phenyl‐C61‐butyric acid methyl ester (P3HT/PC61BM) submicron layers. The used scanning rates of 30 000 K s−1 allow for a ‘true’ isothermal study, where non‐isothermal effects are avoided. Results were obtained over a wide temperature range for the 1:1 composition, used in organic solar cells, and for selected temperatures for the 3:7 composition. The results can be clearly interpreted according to the eutectic behaviour expected for this system, with the 1:1 composition being enriched in P3HT and the 3:7 composition being enriched in PC61BM. In both cases, the start of the melting trajectory corresponding to the eutectic transition coincided with the Tg of PC61BM. This is in agreement with earlier studies that report a vitrification effect caused by PC61BM. A bell‐shaped curve of isothermal crystallization rates could be constructed for the 1:1 composition, where the Tg of the mixed amorphous phase as well as of the separate components can be seen to play a role. For the 3:7 composition, clear indications are observed that a vitrified PC61BM phase can be formed in which isothermal crystallization takes place.

Microcalorimetryisananalyticaltoolthatallowsthedirectmea-surementofheatgeneratedbybiologicalprocessesinlivingcells.Due to its high sensitivity, accuracy, and simplicity, the methodhas been widely employed in biology, microbiology, pharma-cology,biotechnology,andecology[1].Althoughnonspecificityof calorimetric signals can be a limiting factor, it can also beadvantageous since it is more likely to discover unknown phe-nomena[2].Indiagnosticmicrobiology,apromisingapplicationofcalorimetry,molecularmethodssuchaspolymerasechainre-action are increasingly used, but these methods are inherentlyrestricted to the detection of the specified pathogens [3].Despite the recent extensive research in living systems’ mi-crocalorimetry, there are only a few practical applications em-ploying this technology. This is mostly caused by the low sam-ple throughput of conventional microcalorimeters. One way tosolve this problem is to use multichannel instruments such asthe TAM 48-channel isothermal microcalorimeter (TA Instru-ments, New Castle, DE, USA). Using this device, Trampuz [4]and Daniels [5] conducted some extensive and successful clini-cal studies of the detection of bacterial contaminations in bodyfluids and analyzed antibiotic resistance of various pathogens.Furthermore, the Swedish company SymCel has recently an