Hydrogen bonding interactions occur very widely in nature. Although individual bonds are relatively weak, their effect on the physical properties of substances can be profound and is responsible for the anomalous properties of water and the secondary structure of proteins. However, the characteristics of hydrogen bonding, such as site specificity and cooperativity, make it difficult to build a general theoretical description of H-bonding systems.
The presence of hydrogen bonds affects both equilibrium and dynamic properties of all macromolecular systems with hydrogen bonds such as mixtures, solutions, gels, etc. However, a statistical description of hydrogen bonding in macromolecular systems is still scarce and incomplete.
If one is to truly understand, and eventually mimic, nature (and its ability to create advanced materials), we must create accurate, verifiable models that have never been used before.
Block copolymers (polymeric materials with two or more components that exhibit remarkable phase separation behaviour on the nanoscale- akin to natural systems) with one hydrogen bonding (HB) and one non-hydrogen bonding block is an important class of materials with application in nanopatterning in microelectronics. In the case when the HB block is self-associating (has both hydrogen donor and hydrogen acceptor groups like amides, alcohols and acids) [1,2], or is mixed with a complimentary acceptor/donor homopolymer [3] or even with a low molecular weight compound [4], sub-10 nm features can be achieved because of high incompatibility with the non-hydrogen bonding block. The physical reason of incompatibility lies in high energy cost of destruction of the network of hydrogen bonds upon uniform mixing. However, the understanding of the effect hydrogen bonds on microphase separation is far from complete.
This Fellowship had been designed to improve understanding of the role of hydrogen bonds on equilibrium behaviour of hydrogen bonding block copolymers. The study had theoretical and experimental parts. The theoretical part was focused on the development of an association model approach which is useful for the description of hydrogen bonding systems in general and apply it, for the first time, to block copolymer systems. Initially, it was planned to incorporate the association model approach into self-consistent field theory in order to get a versatile tool to predict equilibrium properties of block copolymer systems. The experimental part would then be aimed at the verification of the theoretical predictions. Moreover, the experimental component had the key objective of training the Fellow in synthesis and characterization of polymer systems (completely new to the Fellow who had previously only ever worked on theoretical systems and not worked in a chemistry laboratory, fabricating materials), enabling her to conduct combined theoretical and experimental research in the field of polymer materials in the future.
[1] Fabrication of Sub-3nm Feature Size Based on Block Copolymer Self-Assembly for Next-Generation Nanolithography. Kwak, J. et al., Macromolecules, 2017, 50(17), 6813-6818. [2] Realizing 5.4nm Full Pitch Lamellar Microdomains by a Solid-State Transformation, Jeong, G. et al., Macromolecules, 2017, 50(18), 7184-7154. [3] Thermodynamic and Morphological Behavior of Block Copolymer Blends with Thermal Polymer Additives, Sunday, D.F. et al., Macromolecules, 2016, 49(13), 4898-4908. [4] Facile and Efficient Modification of Polystyrene-block-poly(methyl methacrylate) for Achieving Sub-10 nm Feature Size, Yoshida, K. et al., Macromolecules, 2018, ASAP, 10.1021/acs.macromol.8b01454
