Siloxane/silarylene copolymers as stationary phases for capillary gas chromatography part I: Evaluation of silanol terminated dimethyl substituted polymers

The thermal stability of silicones can be improved on replacement of certain of the oxygen atoms in the polymer backbone by phenyl groups. Such a polymer has been synthesized and evaluated for use as stationary phase in fused silica capillary gas chromatography; the polymer was dimethyl substituted and silanol terminated. A selectivity was provided by the phenyl groups in the backbone. For comparative purposes, a silanol‐terminated dimethylpolysiloxane has also been evaluated. Both stationary phases gave columns of highest separation efficiency and the supporting fused silica surface was deactivated by the stationary phases on thermal treatment. Further, low column bleeding was observed at the maximum temperature tested, 370°C. The phenyl‐containing phase could be immobilized to 60% by heat treatment, but the pure dimethylpolysiloxane was 10% immobilized. The influence on immobilization of factors such as nature of the supporting surface, stationary phase silanol content, reaction temperature and atmosphere in the column during reaction has been studied.