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To date, scalability limitations have hindered the exploration and application of sequence-defined polymers in areas such as synthetic plastics, fibers, rubbers, coatings, and composites. Additionally, the impact of sequence on the properties of cross-linked networks remains largely unknown. To address the need for synthetic methods to generate sequence-defined materials in gram quantities, we developed a strategy involving inexpensive and readily functional vanillin-based monomers to assemble sequence-defined polyurethane oligomers via sequential reductive amination and carbamation. Three oligomers were synthesized with monomer sequence precisely dictated by the placement of reactive side chains during the reductive amination reaction. Avoiding excessive chromatographic purification and solid- or liquid-phase supports enabled synthesis of sequence-defined oligomers on the gram-scale. Remarkably, sequence was shown to influence network topology upon cross-linking, as evidenced by sequence-dependent rubbery moduli values. This work provides one of the first examples of a scalable synthetic route toward sequence-defined thermosets that exhibit sequence-dependent properties.

We report the synthesis and solution characterization of poly(L-lysine)-b-poly(propylene oxide)-b-poly(L-lysine) (KPK) triblock copolymers with high lysine weight fractions (>75 wt%). In contrast to PK diblock copolymers in this composition range, KPK triblock copolymers exhibit morphology transitions as a function of pH. Using a combination of light-scattering and microscopy techniques, we demonstrate spherical micelle-vesicle and spherical micelle-disk micelle transitions for different K fractions. We interpret these morphology changes in terms of the energy penalty associated with folding the core P block to form a spherical micelle in relation to the interfacial curvature associated with different charged states of the K block.

Some dynamic mechanical properties of a series of polymethacrylic and polychloroacrylic esters have been measured over a wide temperature range at about 200 c.p.s. using a cantilever vibration method. The sharp changes in dynamic modulus, and the associated mechanical loss maxima, which occur at various temperatures are discussed in relation to the chemical structures of the polymers and in particular to the ester group in their side chains. The main softening region is shown to be influenced by the presence of polar atoms in both the main and the side chains and by the spatial size and flexibility of the side chains. The data further support the recently postulated view that a secondary dispersion occurring just below the main softening region is associated with rearrangements of the CO.Ogroup in the side chains. Some new low temperature transitions are reported, one of which at −30°C. is characteristic only of polycyclohexyl methacrylate and polycyclohexyl chloroacrylate; it is suggested that this is associated with intramolecular flexibility within the cyclohexyl ring. Another process occurring at about −150°C. is found for those polymers whose linear side chain alkyl components possess sufficient flexibility to enable them to take up more than one unique spatial configuration; such flexibility is characteristic of the n‐propyl, n‐butyl, and sec‐butyl esters in both series and of the β‐chloroethyl, neopentyl carbinyl, and stearyl esters in the polymethacrylic series. Finally, the strengths of the low temperature relaxation processes, defined in terms of the percentage modulus change, are compared and discussed.

In this work, a postpolymerization surface modification approach is reported that provides pendent thiol functionality along the polymer brush backbone using the photolabile protection chemistry of both o-nitrobenzyl and p-methoxyphenacyl thioethers. Poly(2-hydroxyethyl methacrylate) (pHEMA) brushes were synthesized via surface-initiated atom transfer radical polymerization, after which the pHEMA hydroxyl groups were esterified with 3-(2-nitrobenzylthio)propanoic acid or 3-(2-(4-methoxyphenyl)-2-oxoethylthio)propanoic acid to provide the photolabile protected pendent thiols. Addressing the protecting groups with light not only affords spatial control of reactive thiol functionality but enables a plethora of thiol-mediated transformations with isocyanates and maleimides providing a modular route to create functional polymer surfaces. This concept was extended to block copolymer brush architectures enabling the modification of the chemical functionality of both the inner and outer blocks of the block copolymer surface.