The present invention relates to an imidazolium oligomer of formula (I) and an imidazolium oligomer or a polymer of formula (II) where the various groups are as defined in the specification. The present invention also relates to the methods for their preparation, antimicrobial composition, antimicrobial gel containing these oligomers and/or polymers of Formula (I) and (II), and uses of these oligomers and/or polymers in the treatment of a microbial infection or disease.