Rheology. Rheological measurements were performed on an Anton Paar modular compact rheometer of type MCR 302 (Anton Paar, Graz, Austria) equipped with a plate-plate geometry of type PP25 with a plate diameter of 25 mm. A Peltier plate was used to control the temperature and a solvent trap was used to prevent evaporation of the solvent. Gels were prepared from homogenized equimolar mixtures of stock solutions of 3 and 5 in a mold fitting exactly the dimension of the probe geometry. The mixture was allowed to react overnight at room temperature.