PUB - Publikationen an der Universität Bielefeld

A homologous series of oligo(amide-triazole)s (OAT) [OAT-CO2H-2n and OAT-COPrg-(2n+1)] with an increasing number of primary amide (CONH) and triazole hydrogen-bonding functionalities was prepared by an iterative synthetic procedure. It was found that their self-assembly and thermoreversible gelation strength had a strong correlation to the number of hydrogen-bonding moieties in the oligomers. There also existed a threshold value of the number of CONH units, above which all the oligomers became organogelators. Hence, oligomers with <= 4 CONH units are devoid of intermolecular hydrogen bonding and also non-organogelating, whereas those that contain >4 CONH units show intermolecular association and organogelating properties. For the organogelators, the T-gel value increases monotonically with increasing number of CONH units. On the basis of FTIR measurements, both the CONH and triazole C-H groups were involved in the hydrogen-bonding process. A mixed xerogel that consisted of a 1:1 weight ratio of two oligomers of different lengths (OAT-CO2H-6 and OAT-CO2H-12) was found to show microphase segregation according to differential scanning calorimetry, thus indicating that oligomers that bear a different number of hydrogen-bonding units exhibited self-sorting to maximize the extent of intermolecular hydrogen bonding in the xerogel state.