Synthesis and characterization of novel polycyclic structures, precursors to high performance polymers Humayun Mandal.

Our primary goal in this thesis was to develop convenient methods for the synthesis of oligomeric polycyclics which could be ring-opened at elevated temperatures in the presence of a catalyst to give new classes of thermoset materials.A simple and commercially attractive approach was utilized to synthesize novolac type resins by reacting p-substituted phenols with formaldehyde using a cation exchange resin as catalyst in the presence of chlorobenzene as solvent.Novel oligomeric polycyclic carbonates were prepared by reacting the multifunctional phenol-formaldehyde resin with excess triphosgene under high dilution conditions. When the oligomeric polycyclic carbonates were heated at elevated temperatures using an initiator, a highly cross-linked network was obtained. In addition, the polycyclics were mixed with a commercial BPA polycarbonate and cured at different temperatures in the presence of a catalyst. When the mixture of BPA polycarbonate with 10 wt.% polycyclic carbonate was cured at 350ºC for 30 min. using a catalytic amount of lithium stearate, it gave a highly cross-linked network.Two series of polycyclic phosphonates were synthesized by reacting the oligomeric phenol-formaldehyde resins with phosphonic dichlorides under high dilution conditions in a polar aprotic solvent. The polycyclic phosphonates were similarly subjected to ring-opening polymerization at elevated temperatures in the presence of an initiator. The crosslinked phosphonates exhibited good flame retardance properties.Two classes of oligomeric siloxane resins were also synthesized by reacting the phenol-formaldehyde novolac type resins with dialkyl or diaryl dichloro, silanes under high dilution conditions. The formation of predominantly polycyclic siloxane structures was revealed by MALDI-TOF MS, Gradient HPLC and 1H NMR. Blends of commercial polysiloxane gums with different proportions of polycyclic siloxane resins were subjected to curing at 300ºC in the presence of KOH catalyst. Polysiloxane gums are highly unstable at 300ºC in the presence of a basic catalyst. However, the cross-linked polysiloxane gum at 30 wt.% loading of polycyclic siloxanes, was sufficiently stable at this temperature.A Bisphenol A dimer (o, o' methylene bridged) was synthesized by a single-pot reaction between formaldehyde and excess BPA using cation exchange resin catalyst. A few novel classes of oligomeric polycyclics with low melt viscosities were synthesized from this dimer under high dilution conditions.A series of co-polycarbonates of BPA were synthesized by the reaction of methylene bridged dimer with BPA and triphosgene. An alternative in-situ polymerization method was also developed to synthesize the BPA co-polycarbonates. These co-polymers containing cross-linkable cyclic carbonate moieties on the backbone, gave thermoset materials when cured at elevated temperatures in the presence of a catalyst.Low molecular weight poly(aryl ether sulfone)s end-capped with metallophthalocyanine moieties were prepared by reacting poly(aryl ether sulfone)s containing o-phthalonitrile end-groups with excess phthalonitrile and metals/metal salts in quinoline. These polymers were characterized in detail by using IR, UV-VIS, 1 H NMR and GPC techniques. Annealing studies on the polymers containing PcM end-groups were undertaken in order to investigate the occurrence of stacking of plithalocyanine rings in the melt. This study was conducted by using a Thermo-Gravimettic/Differential Thermal Analysis (TG/DTA) instrument