Precise Amphiphilic Giant Polymeric Chain Based on Nanosized Monomers with Exact Regio-Configuration

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Conformational asymmetry of block copolymers is a critical molecular parameter dictating the self-assembly behaviors. This work develops an efficient approach to construct block copolymers with uniform chain length and tunable conformational mismatch. Three model discrete diblock copolymers based on γ-alkyl-α-hydroxy glutaric acid and lactide monomers were prepared through the iterative growth approach. The conformational asymmetry can be adjusted via simple substitution of the hydrocarbon side chains. The precise chemical structure rules out all molecular uncertainties associated with statistical distribution, providing a delicate platform for quantitatively resolving the intricate details and underlying principles. Diverse ordered structures, including the Frank–Kasper σ and A15 phases and quasicrystalline phase, were captured. A phase portrait with an exceptionally high compositional resolution was mapped, demonstrating clearly that the spherical packing region expands and the complex phases emerge as the conformational asymmetry increases. This study explicitly correlates the origin of the intriguing structures with the intrinsic molecular parameters, providing deep insights into the formation and evolution of the complex phases in block copolymers.

Section: ■ Introductionmentioning

confidence: 99%

Discrete Diblock Copolymers with Tailored Conformational Asymmetry: A Precise Model Platform to Explore Complex Spherical Phases

Zhou

et al. 2022

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“…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 ).…”

Section: Introductionmentioning

confidence: 99%

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

Gan

Zhou

et al. 2022

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The Frank–Kasper phase and quasicrystalline phase are an intriguing class of complex crystalline structures, which so far are sporadically observed only in a limited number of block copolymers. Incorporation of a homopolymer into a block copolymer has recently been demonstrated as an effective and robust approach to regulate the formation and evolution of these complex spherical phases. The experimental explorations, however, suffer from inherent chain length distribution of the blending stocks. In this study, we quantitatively assessed the phase behaviors of the block copolymer/homopolymer binary blends using discrete species with a precise chemical structure and uniform chain length, ruling out all interferences associated with chemical heterogeneities. Diverse spherical packings, including σ, A15, C15, and C14 phases, were captured by rationally tuning the chain length and loading content of the homopolymer. The short chains swell the spherical core and drive a transition toward the lattices with a lower interfacial curvature (i.e., σ → A15 → HEX), whereas the long chains localize in the center of the core and prompt the formation of the Frank–Kasper phases with the increasing particle volume asymmetry (C15 and C14). The experimental observation validates the recent theoretical advances, demonstrating that the blending strategy is a robust approach for structural engineering.

“…4−6 They are precisely and modularly synthesized from a library of giant monomers in an either main-chain or side-chain manner. 7,8 The giant monomers are commonly shape-persistent organic/inorganic nanoentities that possess particular symmetry, uniform sizes, and precise chemical compositions. Their species covers a broad range of elements, including molecular clusters, 9−11 polyoxometalates, 12,13 fullerenes, 14,15 polyhedral oligomeric sesquioxanes (POSS), 16−18 etc.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Since the introduction of Staudinger’s macromolecular hypothesis a century ago, the chain paradigm of macromolecules has been well developed, and materials made of those long-chain molecules have become ubiquitous in the modern world. Recently, a trend is clear that the classical paradigm is shifting to expand the scope of Staudinger’s definition of polymers. , As an emerging class of macromolecules, giant molecule chains refer to the size-amplified version of classical linear polymers, yet with more accurate chemical structures (e.g., size, shape, sequence, and topology) and discrete molecular weights. − They are precisely and modularly synthesized from a library of giant monomers in an either main-chain or side-chain manner. , The giant monomers are commonly shape-persistent organic/inorganic nanoentities that possess particular symmetry, uniform sizes, and precise chemical compositions. Their species covers a broad range of elements, including molecular clusters, − polyoxometalates, , fullerenes, , polyhedral oligomeric sesquioxanes (POSS), − etc.…”

Section: Introductionmentioning

confidence: 99%

Crystallization of Precise Side-Chain Giant Molecules with Tunable Sequences and Functionalities

Feng

Shao

et al. 2021

Side-chain giant molecules, constructed from giant monomers by precision synthesis, are viewed as a size-amplified analogue of conventional linear polymers. The molecular accuracy in terms of composition, sequence, topology, and functionality makes these precise macromolecules an ideal platform to investigate the interplay of various molecular parameters in their hierarchical assembly processes. In this study, we studied the crystallization of two sets of amphiphilic side-chain giant molecules with elegantly designed chain sequences and functionalities. When crystallizing from dilute solutions, they form well-defined two-dimensional (2D) crystals with a unique sequence-independent feature. In-depth structural characterization suggested a sandwich-like configuration with head-to-head packing of the side-chain components. Interestingly, the chain stem orientation is supposed to be perpendicular to the normal direction of the nanosheet crystals, which was distinct from the classic folded-chain model of conventional linear polymers. Besides, by intentionally altering the functional groups of the non-crystalline moieties to be non-ionic, cationic, or anionic, we proposed that the solvation effect played a key role in inhibiting the crystal stacking along the surface normal direction and thus in stabilizing the 2D crystals. Our findings revealed the unique crystallization behavior of precise side-chain giant molecules and might provide a strategy to engineer 2D nanomaterials with pre-programmed compositions and functions.