In the quest to develop smart materials that respond to light, researchers have long grappled with understanding how the environment within a material influences the behavior of molecular photoswitches. These tiny molecular switches can change their structure in response to light, enabling a wide range of applications, from adaptive optical devices to controlled drug delivery systems. Now, a team of scientists led by Keiichi Imato from Hiroshima University’s Applied Chemistry Program has shed new light on this complex interplay, with findings that could significantly impact the energy sector and beyond.
The study, published in the journal *Science and Technology of Advanced Materials* (which translates to *Advanced Materials Science and Technology*), focuses on spiropyran (SP), a well-known photoswitch that changes its polarity when it isomerizes to merocyanine (MC) upon exposure to light. The researchers incorporated SP into diblock copolymers (dBCPs), which are polymers made up of two distinct blocks that can self-assemble into ordered or disordered microphase-separated structures.
“What we found is that the rates of both the forward and reverse photoisomerization processes of SP are significantly affected by whether the surrounding polymer environment is ordered or disordered,” Imato explains. “However, the actual yield of the isomerization process remains largely unaffected by the microphase separation.”
This discovery is crucial for the design of photoresponsive smart materials. By understanding how the environment within a material influences the behavior of photoswitches, researchers can better tailor these materials for specific applications. For instance, in the energy sector, photoresponsive materials could be used to develop more efficient solar cells or adaptive window coatings that can regulate the amount of light and heat entering a building.
The team synthesized a series of dBCPs with varying compositions, molecular weights, and microphase-separated structures. They found that the rates of photoisomerization differed substantially between ordered and disordered structures but were comparable among the different ordered morphologies. This suggests that the overall order within the material, rather than the specific type of ordered structure, is the key factor influencing the behavior of the photoswitches.
“This research provides valuable insights into the molecular and polymer design of photoresponsive smart materials,” Imato says. “It will contribute to the further development and application of these materials in various fields, including the energy sector.”
The findings could lead to the development of more efficient and adaptable materials for energy harvesting and storage, as well as for building design and construction. By harnessing the power of light to control the properties of materials, researchers can create innovative solutions that address some of the most pressing challenges in the energy sector.
As the world continues to seek sustainable and efficient energy solutions, the work of Imato and his team offers a promising path forward. By understanding and controlling the behavior of photoswitches within materials, we can unlock new possibilities for a brighter, more energy-efficient future.