<br/>Systematically controlling polymer chain architecture, such as in the transition from linear to bottlebrush polymers via polymer grafting, is an exciting way to dictate material properties. Increasing the number of polymer grafts per strand of a chemically crosslinked elastomer simultaneously reduces the material modulus and promotes strain stiffing, which is attributed to strand backbone extension arising from steric repulsion between neighboring chains. Additionally, incorporation of bottlebrush polymers to the mid-block of an ABA triblock copolymer plastomer further enhances the strain-stiffing properties as compared to the crosslinked bottlebrush elastomer counterparts. Although the effects of chain architecture on mechanical properties of elastomers and plastomers are apparent, the impact of grafted bottlebrushes from nanoparticle surfaces on the physical properties of such systems is not known. Here, the presentation will discuss recent findings regarding the synthesis of bottlebrush polymer grafted silica nanoparticles with controlled molecular weight and block sequences using surface-initiated ring opening metathesis polymerization (SI-ROMP). Specifically, a series of poly(styrene) (PS), poly(dimethylsiloxane) (PDMS), and poly(ethylene oxide) (PEO) bottlebrush grafted silica nanoparticles with varying molecular weight were successfully synthesized. Furthermore, the effectiveness of SI-ROMP enables the possibility of synthesizing PDMS-PS grafted bottlebrush block copolymers that self-assemble into hybrid bottlebrush/nanoparticle plastomers in which the nanoparticles and microphase separated PS domains act as physical crosslinks. The precise synthesis of hybrid bottlebrush plastomers opens new avenues for tailoring mechanical responses via polymer chain architecture and physical properties imparted by the choice of the nanoparticle component.

Synthesis of hybrid plastomers using bottlebrush block copolymer grafted nanoparticles

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ACS Fall 2022

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