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Engineering Orthogonality in Supramolecular Polymers: From Simple Scaffolds to Complex Materials
Conspectus Owing to the mastery exhibited by Nature in integrating both covalent and noncovalent interactions in a highly efficient manner, the quest to construct polymeric systems that rival not only the precision and fidelity but also the structure of natural systems has remained a daunting challe...
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| Published in: | Accounts of chemical research 2014-08, Vol.47 (8), p.2405-2416 |
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| Main Authors: | , , |
| Format: | Article |
| Language: | English |
| Citations: | Items that this one cites Items that cite this one |
| Online Access: | Get full text |
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| Summary: | Conspectus Owing to the mastery exhibited by Nature in integrating both covalent and noncovalent interactions in a highly efficient manner, the quest to construct polymeric systems that rival not only the precision and fidelity but also the structure of natural systems has remained a daunting challenge. Supramolecular chemists have long endeavored to control the interplay between covalent and noncovalent bond formation, so as to examine and fully comprehend how function is predicated on self-assembly. The ability to reliably control polymer self-assembly is essential to generate “smart” materials and has the potential to tailor polymer properties (i.e., viscosity, electronic properties) through fine-tuning the noncovalent interactions that comprise the polymer architecture. In this context, supramolecular polymers have a distinct advantage over fully covalent systems in that they are dynamically modular, since noncovalent recognition motifs can be engineered to either impart a desired functionality within the overall architecture or provide a designed bias for the self-assembly process. In this Account, we describe engineering principles being developed and pursued by our group that exploit the orthogonal nature of noncovalent interactions, such as hydrogen bonding, metal coordination, and Coulombic interactions, to direct the self-assembly of functionalized macromolecules, resulting in the formation of supramolecular polymers. To begin, we describe our efforts to fabricate a modular poly(norbornene)-based scaffold via ring-opening metathesis polymerization (ROMP), wherein pendant molecular recognition elements based upon nucleobase-mimicking elements (e.g., thymine, diaminotriazine) or SCS-PdII pincer were integrated within covalent monofunctional or symmetrically functionalized polymers. The simple polymer backbones exhibited reliable self-assembly with complementary polymers or small molecules. Within these systems, we applied successful protecting group strategies and template polymerizations to enhance the control afforded by ROMP. Main-chain-functionalized alternating block polymers based upon SCS-PdII pincer–pyridine motifs were achieved through the combined exploitation of bimetallic initiators and supramolecularly functionalized terminators. Our initial design principles led to the successful fabrication of both main-chain- and side-chain-functionalized poly(norbornenes) via ROMP. Utilizing all of these techniques in concert led to engineering o |
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| ISSN: | 0001-4842 1520-4898 |
| DOI: | 10.1021/ar500128w |