Adhesion of marine fouling on surfaces such as ship hulls, pipelines, and fishing nets causes higher fuel consumption and maintenance costs. Microorganism settlement on medical equipment also causes infection to patients. To overcome these problems, amphiphilic cationic polymers containing a quaternary ammonium moiety can be used to prevent settlement. The positive charges of ammonium groups along the polymer chains destructively interact with the negative charge on the cell wall of bacteria, inhibiting bacteria adhesion. Longer alkyl chains off the ammonium improve antimicrobial activity due to better hydrophobic interaction with the cell wall. A challenge with linear polymers is that their flexible structures lead to different morphologies when wet versus dry, likely changing their anti-fouling ability. Bottlebrush polymers with dense branches off the polymer backbone are less flexible and help stabilize the structure when they are used under water, potentially improving their anti-biofouling nature. To create bottlebrush polymers with dense branches of quaternary ammonium macromonomers quaternary ammonium salt polymers from poly(dimethylamino ethyl acrylate) (quaternary PDMAEA-Ca, where a is the number of carbons in alkyl group) were synthesized through ring opening metathesis polymerization (ROMP). Prior to ROMP, the tertiary amine macromonomers of PDMAEA were made via reversible addition-fragmentation chain transfer (RAFT) polymerization to generate polymers with a polymerizable norbornene end group with the desired molecular weight. The PDMAEA macromonomers were reacted with butyl bromide, hexyl bromide, and dodecyl bromide to obtain quaternary ammonium polymers with different length alkyl chains. Quaternary PDMAEA-C4, PDMAEA-C6 and PDMAEA-C12 macromonomers were synthesized via RAFT polymerization and subsequent quaternization. Bottlebrush polymers were synthesized by ROMP with different molecular weights by varying the macromonomer to catalyst ratio. Changes to the length of the alkyl chain and polymer molecular weight affected polymer solubility and morphology in water.

Synthesizing amphiphilic cationic bottlebrush polymers for anti-marine fouling

256th National Meeting (2018)

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