Figure 5
SF = sol fraction; GF = gel fraction; MWR = microwave radiation; CTS = conventional thermal system; AH = acid hydrolysed sample; NH = unhydrolysed samples; a and b = GC–MS methods (please see experimental section). (a) GC–MS profiles of unhydrolysed and acid hydrolysed samples from the NH4CN polymerization under anoxic conditions and microwave radiation using a reaction time of 30 min. Note that in the GC–MS profile of an unhydrolysed gel fraction sample, no well-defined polar organic compounds were identified and the relative intensity of the chromatogram signal is very low; (b) Semiquantitative analyses of the acid hydrolysed sol fractions. A value 1 is taken for the area of the urea peak plus the area of the glycine peak (3TMS) (please see the peak assignments in Figs. S5 and S6) in the sol fractions from the polymerization conducted at 2 min (Fig. S6). The other relative area values refer to that. Note that there are several saturated and coelution peaks. The assignment of the analytes was made using the retention time values and the profile of the mass spectra of the authentic standards. (c) Semiquantitative analyses of the acid hydrolysed gel fractions were performed in the same way as for the acid hydrolysed sol fractions. (d) Qualitative comparative analyses of the gel and sol fractions. The letter and number shown in the axis correspond to the analyte numeration indicated in Fig. 4.
