Copolymer of ethylene oxide and at least one substituted oxirane carrying a cross-linkable function, process for preparation thereof, and use thereof for producing ionically conductive materials

A process for the preparation of a copolymer in a stainless steel reactor;

• said copolymer having a chain comprising ethylene oxide, —O—CH2—CHR units, in which R is a substituent having a reactive function cross-linkable by free radical process, and optionally, —O—CH2—CHR′ units, in which R′ is a substituent having no reactive function cross-linkable by free radical process;
• said copolymer having a polydispersity index (I)=Mw/Mn lower than or equal to 2.2, a number average molecular weight Mn greater than or equal to 20,000 and a random distribution of monomer units;
• said process comprising the steps of:
• drying said stainless steel reactor by washing it with a solution containing an initiator and removing said initiator before the introduction of the reagents in order to remove impurities therefrom;
• distilling said ethylene oxide, and drying an aprotic solvent and the monomer units on molecular sieves in order to lower their water content to less than 100 ppm;
• and
• reacting said ethylene oxide and said monomer units in said stainless steel reactor in said aprotic solvent in the presence of an anionic polymerization initiator to yield said copolymer.