Perimeter sealant for an electrochromic device

A method of forming an electrochromic device comprising a sealant comprising a melt processable polymer, comprising:

• a. providing a first coated glass substrate comprising a first glass substrate having a conductive coating on a surface thereof and wherein the first coated glass substrate optionally has at least one redox coating over the conductive coating;
• b. placing a thermoplastic electrolyte film and the sealant to contact at least one of the conductive coating and the at least one redox coating of the first coated glass substrate such that the sealant surrounds the perimeter of the thermoplastic electrolyte film to form a first assembly;
• c. providing a second substrate having a conductive coating on a coated side thereof, wherein the second substrate optionally has one or more redox coatings over the conductive coating on the assembly, and placing the coated side of the second substrate to contact the thermoplastic electrolyte film and the sealant of first assembly formed in step b, thereby sandwiching the sealant and the thermoplastic electrolyte film;
• d. performing a lamination process comprising subjecting the said assembly formed in step c to pressure and heat so that the sealant and the thermoplastic electrolyte film flow and bond to coatings on the said substrates that the thermoplastic electrolyte film and the sealant contact,
• wherein (i) the melt processable polymer is a block copolymer having two phases, wherein a first phase has a lower glass transition temperature and (ii) a second phase of the melt processable block copolymer determines its flow or melting point which is in excess of 100° C., (iii) the first phase has a volume fraction that is greater than that of the second phase, (iv) at least one of the said conductive coatings is transparent, and (v) either the thermoplastic electrolyte film contains an electrochromic material or at least one of the said redox coatings is present having electrochromic properties, or the thermoplastic electrolyte film contains an electrochromic dye and at least one of the said redox coatings is present having electrochromic properties.