Amplifying (Im)perfection: The Impact of Crystallinity in Discrete and Disperse Block Co-oligomers

Abstract

Crystallinity is seldomly utilized as part of the microphase segregation process in ultralow-molecular-weight block copolymers. Here, we show the preparation of two types of discrete, semicrystalline block co-oligomers, comprising an amorphous oligodimethylsiloxane block and a crystalline oligo-l-lactic acid or oligomethylene block. The self-assembly of these discrete materials results in lamellar structures with unforeseen uniformity in the domain spacing. A systematic introduction of dispersity reveals the extreme sensitivity of the microphase segregation process toward chain length dispersity in the crystalline block.

Stereochemical Sequence Dictates Unimolecular Diblock Copolymer Assembly

“…5c, 8a Similarly, Meijer and co-workers recently reported on oligodimethylsiloxane- b -oligo(L)lactides that crystallize and assemble into lamellae. 8d, 15 Here again, our results show how stereochemistry can lead to dramatic changes in DPT assembly, switching from crystalline to amorphous materials.…”

Multiphase‐Assembly of Siloxane Oligomers with Improved Mechanical Strength and Water‐Enhanced Healing

“…Large scale continuous nanofibrous structures were observed on the polymer films (Figure a,b), and powder X‐ray diffraction (XRD) confirmed the semi‐crystalline property of the microphase‐separated supramolecular polymer (Figures S2b,S3) . The semi‐crystalline supramolecular polymer can readily be melt‐processed into transparent solid objects by heating the as‐prepared grains above the melting point (Figure S4), indicating thermoplastic characteristics.…”

Multiphase‐Assembly of Siloxane Oligomers with Improved Mechanical Strength and Water‐Enhanced Healing

“…During the assembly process,t he UPy dimers would further assemble into larger stacks with high crystallinity,e specially when intermolecular urea hydrogen bonds exist, [12] Large scale continuous nanofibrous structures were observed on the polymer films ( Figure 1a,b), and powder X-ray diffraction (XRD) confirmed the semi-crystalline property of the microphase-separated supramolecular polymer ( Figures S2b,S3). [13] Thes emi-crystalline supramolecular polymer can readily be melt-processed into transparent solid objects by heating the as-prepared grains above the melting point ( Figure S4 Figure S5) at room temperature.T he obtained polymer can also be repeatedly pulverized and processed to new films through melting. Little decrease of mechanical properties was observed from the tensile-test results of recycled polymers even after the fifth cycles of reprocessing ( Figure 1c and Table S1).…”