Patent ID: 6869719

Claim:
A polymer electrolyte fuel cell stack comprising a plurality of unit cells, each unit cell comprising a polymer electrolyte membrane, a pair of electrodes arranged across said polymer electrolyte membrane and having respective catalytic reaction layers, a first separator having means for feeding a supply of fuel gas containing hydrogen gas to one of said electrodes, and a second separator having means for feeding a supply of oxidant gas to the other of said electrodes, and a manifold for feeding at least one of the supply of fuel gas and the supply of oxidant gas to the respective electrodes, the manifold being disposed on a side face of the stack of unit cells, and a sealing portion being disposed inside of the manifold, wherein said sealing portion is constituted by a polymer compound expressed by formula (1): wherein R 1 and R 2 are non-functional end groups; X i and Y i are independently polymerizable functional groups and form crosslinking points after polymerization; m is an integer of not less than 1 and represents a number of repeated isobutylene oligomer units; and i is an integer of not less than 1 and represents the degree of polymerization.