Photosensitive Block Copolymers as Organic Phase Change Materials

• Applicant: Dr.-Ing. Jochen Kammerer
• Subject Area: Polymer Materials
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 500289223

The properties of organic functional materials are critically determined by their morphology. Yet, the potential of morphological transformations to gain spatiotemporal control over the properties of materials is still in its infancy. Block copolymers (BCPs) offer excellent prerequisites for dynamic morphological transformations and hold the potential to form an entire new class of functional materials with stimuli responsive properties: organic solid-state phase change materials. BCPs self-assemble into various ordered phased with well-defined morphology. Within the proposed project, a α-bisimine photo-switch will be incorporated into the backbone of one polymer block, capable of undergoing a Z/E-photoisomerization upon UV-light irradiation. The macromolecular reorganization of the light-responsive BCP (LR-BCP) induced a phase transformation, which is associated with severe morphological alterations and an unprecedented modification of the material’s properties. The synthetic efforts to generate the LR-BCPs will be critically underpinned by molecular insights into the morphological transformations from in-situ transmission electron microscopy (TEM). Superior spatial and temporal resolution of in-situ TEM come at the price of experimental challenges, including potential beam damage and the application of the light stimulus within the microscope. The combination of dedicated in-situ TEM equipment, antioxidative additives and machine learning enhanced data processing will be employed to overcome these hurdles and set new standards for the in-situ TEM investigation of organic functional materials. The generated insights into the transformation dynamics will be directly translated into an optimized LR-BCP design. The optimised LR-BCP will serve as an archetype of organic solid-state phase change materials and a generalization of the established design rationales toward other stimuli responsive BCPs is anticipated. Based on this fundamental effort, novel dynamic functional materials can be envisaged: mechanically adaptive plastics, solid-state electrolytes and membranes with spatiotemporal controllable permeability as well as smart soft electronics.

• DFG Programme: WBP Fellowship
• International Connection: Australia
• Host: Professor Dr. Christopher Barner-Kowollik