Polypeptoids are non-natural, sequence specific polymers that offer the opportunity to probe the effect of monomer sequence, charge, chirality, and chain shape on self-assembly and surface properties.  Although examples of hierarchical polypeptide structures abound in nature, the de novo design of such systems is still a major challenge.  The polypeptoid system with its much simplified set of inter and intramolecular interactions provides an opportunity to explore this design space with more tractable systems.  In this talk, the role of chirality and molecular helicity in relatively simple block copolymer architectures as well as the more complicated assembly of achiral molecules into homochiral superstructures will be discussed.  While helical chain shapes in block copolymers have been shown to produce unique morphologies, polypeptoids provide a unique opportunity to understand the details of how chain shape influences the thermodynamics of self-assembly.  We utilize model coil–coil and coil–helix block copolymers based on polypeptoids, for which the chain shape can be tuned from helix to coil via monomer chirality with constant chemistry.  With identical domain spacings in the lamellar morphology, the coil–helix block copolymer has a lower order–disorder transition temperature (T ) than its coil–coil analogue. There is minimal difference in the enthalpic contribution to mixing. The most significant contribution in lowering the T of the coil–helix block copolymer is the helical chain experiencing larger chain stretching penalties in the lamellar morphology, which leads to a larger entropic gain upon disordering. This yields insight into the importance of space filling and chain stretching of polymer chains in block copolymer self-assembly.<br/>

Using bioinspired polypeptoids to understand how chain shape influences self-assembly

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.