The field of polymer science and materials engineering is advancing with new assembly processes that allow for the implementation of nanoscale structures and orders at a more affordable cost. Layer-by-layer (LbL) adsorption, which was introduced 30 years ago, has revolutionized the understanding and application of electrostatic assembly. This has resulted in a rapid expansion of the field, generating new scientific insights and engineering applications. Chemical engineers have mainly explored its use in reactive and passive membranes, drug delivery systems, and electrochemical and sensing devices. The 2024 Franklin Medal Laureate Professor Paula T. Hammond has been at the forefront of this progress.Professor Paula T. Hammond has been instrumental in the advancement of this field since its inception. The LbL method allows for the sequential and precise assembly of different charged species, from molecules and polymers to colloidal and nano-to-microscale materials. The assembly is driven by alternating charge interactions or complementary bonding, such as hydrogen bonding. LbL offers unprecedented control over materials selection, properties, and architecture by alternatingly adsorbing oppositely charged species from aqueous solutions. This near-molecular control enables the design of functional materials with widely tunable structural, optical, electrical, and chemical properties. The ability to incorporate an array of building blocks into nanoscale thin films allows for control of film composition across its thickness, which is crucial for many emerging applications. Engineering opportunities span biology, medicine, energy conversion, storage (fuel cells, batteries, electrochromic devices, and solar cells), and sensors.Professor Paula T. Hammond is recognized for being at the forefront of developing LbL and related electrostatic polymer assembly techniques that create entire families of nanostructured polymer and composite systems. Her innovative materials display outstanding static properties as well as a range of dynamic (environmentally responsive) properties. LbL offers a multitude of advantages for biological applications and excels in its impact on drug delivery. Cytocompatibility, engineering the drug loading versatility, film stability, and protecting the payload and its controlled release are paramount for the successful translation of LbL drug delivery systems.Professor Hammond has translated her scientific insights into practical applications in medicine and sustainable energy, nurturing their commercial exploration, expanding their technical impact, and inspiring a generation of soft matter nanomaterials scientists and engineers.
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