Design and Synthesis of a Polymer Hydrogel with Effective Crosslinking via Bottlebrush Polymers

Seed 3
PI: Rob Macfarlane

Macfarlane and Holten-Andersen (IRG-II) have developed a novel design approach for synthesizing hydrogels that minimizes the formation of topological defects via the use of bottlebrush polymers. We have synthesized end-functionalized bottlebrush polyethylene glycol (PEG) polymers, which, due to the backbone rigidity imparted by a dense polymer brush makes these gel building blocks much less susceptible to the formation of cyclic defects and intermolecular entanglements. As a result, bottlebrush polymeric-based hydrogels achieve percolation and rigidity at much lower crosslink concentrations than gels made with flexible polymers. Furthermore, we show that our design enables the prolonged release of encapsulated molecules, thus demonstrating promise for biomedical applications.

Bottlebrush PEG crosslinked via covalent bonds leads to network structures with minimal entanglement and topological defects. This leads to enhanced mechanical properties and  slower molecule release profiles, making them ideal for biomedical applications.


During 2018, the Macfarlane lab provided education and research opportunities for local community colleges (Roxbury and Bunker Hill Community Colleges) that support underrepresented groups.

Both a visiting student and a visiting RCC professor performed 10-week independent research projects, guided by graduate student mentors. At the end of these 10 weeks their research results were presented at a MIT conference as a research poster.

The faculty member has also (in conjunction with Professor Macfarlane) used her research experiences to develop coursework for an introductory chemistry class at RCC, and this work is now part of the class curriculum.

Alternative text: Kimberly Steiglitz and Credoritch Joseph performed research in the Macfarlane lab, developing new polymer-based materials.