biocidal branched quaternary ammonium polymers are made by condensing a difunctional halide with a trifunctional tertiary amine and optionally with a difunctional amine . the branched quaternary ammonium polymers have 2 - dimensional conformation that provides better coverage over the surfaces of microorganisms and enhances efficacy as biocides as compared to most commercially available linear quaternary ammonium polymers . the bulkier 2 - dimensional conformation of this invention limits the uptake , accumulation and release of these branched polymers to and from contact lenses . therefore , these branched quaternary ammonium polymers can reduce the cytotoxicity , enhance compatibility and suitable for ophthalmic use . the highly branched polymers can be prepared with minimum or no difunctional tertiary amines . the lightly branched polymers can be prepared with of a minimum ratio of trifunctional tertiary amines / difunctional tertiary amines .