Phantom polyguanidines by ring-closing condensation polymerization: Mechanistic studies and properties investigations

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Ring-polyguanidines are in the focus of this proposal. The objective of the proposed project is to get basic understanding of a new type of phantom ring-closing polymerization for the synthesis of ring polyguanidines and investigate their properties in details in one of the application areas, for example, as antibacterial polymers. Linear polyguanidines synthesized by the reaction of diamines with guanidine hydrochloride are known. In contrary, ring polyguanidines are not known in the literature. The hypothesis of proposal is that by choice of appropriate monomers (i.e. suitable amines) for condensation polymerization with guanidine hydrochloride, novel ring structures can be synthesized which are otherwise not accessible. The different reactivities of primary and secondary amines in nucleophilic addition reactions in combination with the appropriate opposite anion during condensation are expected to provide phantom polymers with ring structures in the repeat unit. The type of anion in guanidine salt could also play a major role in controlling the final polymer structure by changing the geometry and stability of the transition states. Experiments using various amines under different condensation reaction conditions of homo- and copolymerizations and quantum chemical calculations are proposed to achieve the objectives. Keeping-in-view our objectives, the expected outcome of the project would be a well-characterised new sub-class of polyguanidines in terms of structure, properties (thermal, antibacterial and cytotoxicity) and mechanistic aspects in theory and experiment.