Precisely Encoding Geometric Features into Discrete Linear Polymer Chains for Robust Structural Engineering

Abstract

Molecular shape is an essential parameter that regulates the self-organization and recognition process, which has not yet been well appreciated and exploited in block polymers due to the lack of precise and efficient modulation methods. This work (i) develops a robust approach to break the intrinsic symmetry of linear polymers by introducing geometric features into otherwise homo­geneous chains and (ii) quantitatively highlights the critical contribution of molecular geometry/architecture to the self-assembly behaviors. Iteratively connecting homologous monomers of different side chains according to pre-designed sequences generates discrete polymers with exact chemical structure, uniform chain length, and programmable side-chain gradient along the backbone, which transcribes into diverse shapes. The precise chemistry eliminates all the defects and heterogeneities, providing a delicate platform for fundamental inquiries into the role of molecular geometry. A rich collection of unconventional complex phases, including Frank–Kasper A15 and σ phases, as well as a dodecagonal quasicrystal phase, were captured in these rigorous single-component systems. The self-assembly behaviors are strikingly sensitive to subtle variations of geometry, such that simply migrating a few methylene units among the side chains would generate substantial differences in lattice size or phase stability, or even trigger a phase transition toward distinct structures. The phenomena can be rationalized with a geometric argument that nonuniform side chain distribution leads to conformational mismatch between two immiscible blocks, resulting in varied interfacial curvatures and distinct lattice symmetries. The profound contribution demonstrates that molecular geometry is an effective and robust parameter for structural engineering.

Modulation of the Complex Spherical Packings through Rationally Doping a Discrete Homopolymer into a Discrete Block Copolymer: A Quantitative Study

“…Discrete polymers with precise chemical structure and uniform chain length provide a delicate system to resolve the details compromised by the molecular weight distribution. ,− In this work, discrete linear-branched block copolymers with three oligo dimethylsiloxane block ( o DMS) and one oligo lactic acid block ( o LA) were synthesized (Scheme b). By blending with discrete o LA homopolymers, nonuniform distribution of the homo-chains within the micellar core and uneven partition of them among different micelles lead to the formation of diverse ordered structures, including σ, A15, C15, and C14 phases (Scheme ).…”

Determination of the critical chain length for macromolecular crystallization using structurally flexible polyketones

“…Determination of the critical chain length for macromolecular crystallization using structurally flexible polyketones † Introduction There has been growing interest in molecularly dened oligomers that combine the molecular precision of organic synthesis with the properties of macromolecules. [1][2][3][4][5][6][7][8] This emerging research area is termed macro-organic chemistry. Interestingly, recent developments, such as the iterative exponential growth (IEG) strategy, facilitate an efficient synthetic access to discrete oligomers.…”

Investigation of eight-arm tapered star copolymers prepared by anionic copolymerization and coupling reaction

“…MALDI-TOF MS was conducted on a mass spectrometer (Ultraflextreme, Bruck Dalton). 57,58 trans-2-[3-(4-tert-Butylphenyl)-2-methyl-2-propenylidene]malononitrile (DCTB, >99%, Sigma-Aldrich) (20 mg mL −1 in CHCl 3 ) was used as a matrix and silver trifluoroacetate (AgTFA, >99%, Sigma-Aldrich) (10 mg mL −1 in ethanol) was used as a cationizing agent, and polymer samples were dissolved in CHCl 3 with a concentration of 10 mg mL −1 . The DCTB and AgTFA solutions were mixed in a ratio of 10/1 (v/v).…”