AbstractSyntheses and properties of some novel functional oligomers and functional or segmental polymers thereof are reported. First part of the paper concerns the synthesis and properties of high performance segmental engineering polymers. These polymers contain crosslinked network units as rigid segments, linked by linear spacers, derived from the functionally terminated thermoplastic oligomers. Structure‐properties relationships are discussed. Second part of the paper refers to the syntheses and possible applications of novel functional oligomers and polymers, containing cyclophosphazene moieties, particular attention being paid to the functional polymers with bioactive aziridinylcyclophosphazene units linked by specific biodegradable spacer