Increasing the side-chain density of grafted polymers changes their definition from comb to bottlebrush (BB) where significant changes in material properties are traversed as the sterics between grafts begin to occupy the pervaded volume near the backbone. Although an almost limitless selection of graft chemistries exist, the number of BB backbone options that allow precise control of high graft density are limited. The maturation of bottlebrush polymers has been highly focused on two types of backbones. One of them is vinyl-based BBs, such as polymer-tethered methacrylates, which teeter on the steric upper limit of grafting density with one carbon atom between each graft site (ng = 1). The other is polynorbornene (PNB) or polyoxonorbornene based BBs which supply a rigid, cyclopentane-tethered, five-carbon repeat unit each with one graft (ng = 4). Therefore, a four-carbon spacing between grafts has been generally accepted as enough graft density to afford a BB system. This talk will discuss our recent success in obtaining a polypentenamer system with low dispersity and targeted molar mass through variable temperature (VT) ROMP. This materials also hosts a functionality capable of initiating a grafting-from polymerization at exactly every five carbons along the backbone. These new BB systems have ng = 4 just like the PNB analogs but have much higher backbone flexibility between graft-sites. Does it still behave like a bottlebrush? We are probing the importance of the backbone chemistry on the resulting BB properties. Synthesis and our preliminary investigations on such properties will be discussed.

Five alive: Functional polypentenamers towards a new class of bottlebrush systems and their place within the structure-property genome

256th National Meeting (2018)

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