Pd-initiated controlled polymerization of diazoacetates with a bulky substituent: synthesis of well-defined homopolymers and block copolymers with narrow molecular weight distribution from cyclophosphazene-containing diazoacetates

Polymerization of cyclophosphazene-containing diazoacetates was carried out using a (eta(3)-C3H5) PdCl-based initiating system to produce sp(3)-sp(3) carbon-carbon main chain polymers bearing a cyclophosphazene-containing ester group on every main chain carbon atom. The obtained polymers had very narrow molecular weight distributions in contrast to the case of other alkyl or aryl diazoacetates reported previously, suggesting that the polymerization of cyclophosphazene-containing diazoacetates proceeded in a controlled manner without apparent side reactions, which was confirmed by MALDI-TOF-MS analysis. In addition, block copolymers with a well-defined structure were successfully synthesized. This is the first report on controlled polymerization of diazoacetates to afford narrow molecular weight distribution polymers. Furthermore, thermogravimetric analysis was conducted to reveal that the resulting polymers had a higher thermal stability compared to the vinyl polymer counterparts.