No abstract

New supramolecular polypeptides have been prepared through simple ring-opening polymerization and “click” reactions. Postfunctionalization with diamino­pyridine (DAP) moieties, capable of multiple hydrogen bonding, was an efficient approach toward forming α-helical-dominant polypeptides. The physically cross-linked networks produced upon self-organization of the DAP units increased the glass transition temperature (T g) of the polymers and sustained the secondary structures of the polypeptides. Additional thermal responsivity resulted from dynamic noncovalent bonding on the polymer side chains. Molecular recognition through heterocomplementary DAP···thymine (T) base pairs was revealed spectroscopically and then used to construct poly­(γ-propargyl-l-glutamate)-g-N-(6-acetamido­pyridin-2-yl)-11-undecan­amide/thyminyl­pyrene (PPLG-DAP/Py-T) supramolecular complexes. Transmission electron microscopy images revealed that this complex was an efficient dispersant of carbon nanotubes (CNTs). Indeed, it could disperse CNTs in both polar and nonpolar media, the direct result of combining two modes of secondary noncovalent bonding: multiple hydrogen bonding and π–π interactions. Furthermore, CNT composites fabricated with biocompatible polymers and high value of T g should enable the development of bio-inspired carbon nanostructures and lead the way toward their biomedical applications.

A supramolecular system stabilized through complementary hydrogen bonding and displaying stimuli-responsive behavior has been fabricated into “recordable” and “rewritable” surface relief gratings operated under laser illumination.

We describe a facile strategy, involving bio-inspired noncovalent molecular recognition, for fabricating water-dispersible luminescent polymer dots without any ionic groups. We first synthesized the thymine-functionalized conjugated polymers PC-T and PTC-T through conventional Suzuki coupling polymerization and copper­(I)-catalyzed alkyne/azide cycloaddition (CuAAC). These multiple-hydrogen-bonding materials exhibited distinct luminescent properties in protic and aprotic solvents as well as attractive thermal properties and stabilities; most importantly, they had the ability to pair with complementary base units. Next, we prepared the hydrophilic polymer PEG-A and examined its molecular recognition with PC-T and PTC-T through DNA-like adenine–thymine (A–T) base pairing. We used transmission electron microscopy (TEM) and dynamic light scattering (DLS) to determine the size distributions and dispersibilities of the resulting supramolecular micelles, which appeared as polymeric dots with high signal-to-background ratios through fluorescence microscopy. The PEG shells of these micelles functioned as biomimetic surfaces that sustained the biocompatibility for practical usage. Our results suggest that supramolecular self-assembly through specific nucleobase recognition appears to be a reliable process with which to apply conjugated polymers into, for example, modern biological analysis.

A facile method to synthesize azobenzene- and thymine (T)-functionalized conjugated copolymers through Suzuki coupling polymerization and click reactions and used in surface relief gratings displaying long-range-ordered interference patterns.