UC Santa Barbara

The design and synthesis of new organic materials is necessary to meet society’s needs. A central tenant of material science is that function follows form. With this in mind: 1) a one-step procedure to a new versatile pentacyclic benzodibenzofuranquinone building block for organic electronic applications is developed; 2) the effect of side-chain topology on conjugated polymer interchain interactions, morphology, and optical properties are studied by comparing a novel macrocyclic benzodithiophene unit to its more traditional linear acyclic analogue; and 3) a short and modular synthetic route to functional and well-defined photocrosslinked bottlebrush networks is developed. All of three of these projects highlight how molecular architecture and design can be used to engineer macroscopic material properties and tailor function from form. In particular, conjugated polymers and organic electronics are an interesting class of materials wherein the electronic properties of the materials are dictated by several hierarchical orders of structure. The primary level of structure is the (co)monomer structure which dictates energetics of the polymer backbone. The aggregation, self-assembly, and interaction of these conjugated polymer chains then form higher-order structures which determine the overall material properties and device performance. Project 1 addresses this primary level of structure by developing simple inexpensive and versatile new building blocks for organic electronic materials. Project 2 studies how higher-order structure and properties of organic electronic materials are impacted by primary molecular structure. This is done by comparing materials based on a macrocyclic benzodithiophene unit which disrupts conjugated polymer aggregation and interchain interactions to materials based on its acyclic linear analogue which does not. Project 3 examines this structure-property mantra through the lens of a different class of materials—soft compliant elastomeric bottlebrush networks. In bottlebrush networks, the macromolecular architecture of the bottlebrush polymers results in their soft and compliant mechanical properties. A concise and modular strategy for synthesizing well-defined and functional photocrosslinkable bottlebrush networks is demonstrated. With versatility in the monomer, macromonomer, bottlebrush polymer, and crosslinked bottlebrush network, these hierarchical levels of structure can be tailored and the resulting macroscopic mechanical and chemical properties can be tuned. This strategy makes these materials more accessible and enables further use of these bottlebrush materials for various applications in fields such as biomaterials.