Characterisation of cyclic and linear poly(isosorbide-ether)s obtained under microwave irradiation by MALDI-TOF mass spectrometry.

摘要

We studied the influence of the alkyl chain length and of the leaving group on the fraction of cychc or linear poly(isosorbide-ether)s.A survey by MALDI-TOF MS showed that cyclic chains (C) are predominant when some short aliphatic chains are used (m = 4 or 6),whereas with longer chains (m = 8,10 or 12),we noted that cyclic products were in a minority,whatever the leaving group (bromide or mesyl).Important non-thermal microwave effects have been demonstrated,notably a methanol-insoluble fraction of polyether considerably larger than the one obtained by conventional heating.These poly(isosorbide-ether)s have been characterized by RMN,MALDI-TOF,SEC,elementary analysis,and DSC.The survey of the thermal behaviour by DSC showed that the temperatures of fusion increase with the aliphatic chain's length (m = 12;T_f = 37 °C).