Self-Sorting of Amphiphilic Block-Pendant Homopolymers into Sphere or Rod Micelles in Water

Ultrasmall Single-Chain Nanoparticles Derived from Amphiphilic Alternating Copolymers

The collapse or folding of an individual polymer chain into a nanoscale particle gives rise to single-chain nanoparticles (SCNPs), which share a soft nature with biological protein particles. The precise control of their properties, including morphology, internal structure, size, and deformability, are a long-standing and challenging pursuit. Herein, a new strategy based on amphiphilic alternating copolymers for producing SCNPs with ultrasmall size and uniform structure is presented. SCNPs are obtained by folding the designed alternating copolymer in N,N-dimethylformamide (DMF) and fixing it through a photocatalyzed cycloaddition reaction of anthracene units. Molecular dynamics simulation confirms the solvophilic outer corona and solvophobic inner core structure of SCNPs. Furthermore, by adjusting the length of PEG units, precise control over the mean size of SCNPs is achieved within the range of 2.8 to 3.9 nm. These findings highlight a new synthetic strategy that enables enhanced control over morphology and internal structure while achieving ultrasmall and uniform size for SCNPs.

Research progress on the conformational properties of comb-like polymers in dilute solutions

As a special type of branched polymers, comb-like polymers simultaneously possess the structural characteristics of a linear backbone profile and crowded sidechain branches/grafts, and such structural uniqueness leads to reduced interchain entanglement, enhanced molecular orientation, and unique stimulus-response behavior, which greatly expands the potential applications in the fields of super-soft elastomers, molecular sensors, lubricants, photonic crystals, etc. In principle, all these molecular features can be traced back to three structural parameters, i.e., the degree of polymerization of the backbone (Nb), the degree of polymerization of the graft sidechain (Ng), and the grafting density (σ). Consequently, it is of great importance to understand the correlation mechanism between the structural characteristics and physicochemical properties, among which, the conformational properties in dilute solution have received the most attention due to its central position in polymer science. In the past decades, the development of synthetic chemistry and characterization techniques has greatly stimulated the progress of this field, and a number of experiments have been executed to verify the conformational properties; however, due to the complexity of the structural parameters and the diversity of the chemical design, the achieved experimental progress displays significant controversies compared with the theoretical predictions. This review aims to provide a full picture of recent research progress on this topic, specifically, (1) first, a few classical theoretical models regarding the chain conformation are introduced, and the quasi-two-parameter (QTP) theory for the conformation analysis is highlighted; (2) second, the research progress of the static conformation of comb-like polymers in dilute solution is discussed; (3) third, the research progress of the dynamic conformation in dilute solution is further discussed. The key issues, existing controversies and future research directions are also highlighted. We hope that this review can provide insightful information for the understanding of the conformational properties of comb-like polymers, open a new door for the regulation of conformational behavior in related applications, and promote related theoretical and experimental research in the community.

Poly(ionic liquid) nanovesicles via polymerization induced self-assembly and their stabilization of Cu nanoparticles for tailored CO2 electroreduction

Herein, we report a straightforward, scalable synthetic route towards poly(ionic liquid) (PIL) homopolymer nanovesicles (NVs) with a tunable particle size of 50 to 120 nm and a shell thickness of 15 to 60 nm via one-step free radical polymerization induced self-assembly. By increasing monomer concentration for polymerization, their nanoscopic morphology can evolve from hollow NVs to dense spheres, and finally to directional worms, in which a multilamellar packing of PIL chains occurred in all samples. The transformation mechanism of NVs' internal morphology is studied in detail by coarse-grained simulations, revealing a correlation between the PIL chain length and the shell thickness of NVs. To explore their potential applications, PIL NVs with varied shell thickness are in situ functionalized with ultra-small (1 ∼ 3 nm in size) copper nanoparticles (CuNPs) and employed as electrocatalysts for CO₂ electroreduction. The composite electrocatalysts exhibit a 2.5-fold enhancement in selectivity towards C₁ products (e.g., CH₄), compared to the pristine CuNPs. This enhancement is attributed to the strong electronic interactions between the CuNPs and the surface functionalities of PIL NVs. This study casts new aspects on using nanostructured PILs as new electrocatalyst supports in CO₂ conversion to C₁ products.

Photo-Cross-Linked Polymeric Dispersants of Comb-Shaped Benzophenone-Containing Poly(ether amine)

Efficient dispersion of nanoparticles (NPs) is a crucial challenge in the preparation and application of composites that contain NPs, particularly in coatings, inks, and related materials. Physical adsorption and chemical modification are the two common methods used to disperse NPs. However, the former suffers from desorption, and the latter is more specific and has limited versatility. To address these issues, we developed a novel photo-cross-linked polymeric dispersant, comb-shaped benzophenone-containing poly(ether amine) (bPEA), using a one-pot nucleophilic/cyclic-opening addition reaction. The results demonstrated that the bPEA dispersant forms a dense and stable shell on the surface of pigment NPs through physical adsorption and subsequent chemical photo-cross-linking, which effectively overcome the drawbacks of the desorption occurred in physical adsorption and the specificity of the chemical modification. By means of the dispersing effect of bPEA, the obtained pigment dispersions show high solvent, thermal, and pH stability without flocculation during storage. Moreover, the NPs dispersants show good compatibility with screen printing, coating, and 3D printing, endowing the ornamental products with high uniformity, color fastness, and less color shading. These properties make bPEA dispersants ideal candidates in fabrication dispersions of other NPs.

Computational and experimental studies on the micellar morphology and emission mechanisms of AIE and H-bonding fluorescent composites

In this work, we use density functional theory (DFT) calculated competitive hydrogen bonds and dissipative particle dynamics (DPD) simulated micellar structural information to uncover the CO2-expanded liquid (CXL)-aided self-assembled structure and emission mechanisms of the self-assembled fluorescent composites (SAFCs). Herein, the SAFCs are formed through the self assembly between diblock copolymer polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) blend and the dye molecule 4-(9-(2-(4-hydroxyphenyl)ethynyl)-7,10-diphenylfluoranthen-8-yl)phenol (4) in CO2-expanded toluene at 313.2 K and varied pressures. Firstly, from DPD simulation, we have demonstrated that the addition of CO2 to toluene favors both the expansion of the solvophobic P4VP phase and contraction of solvophilic PS chains, which facilitates the continuous morphological transitions of SAFCs from spherical micelles (3.0 MPa) through wormlike plus spherical micelles (4.0-4.8 MPa) to large vesicles (6.0-6.5 MPa) with pressure rise. Secondly, the DFT calculated bonding energies and IR spectra of the competitive hydrogen bonds help us to clarify the major type of hydrogen bonds determining the fluorescence (FL) performance of the SAFCs. Furthermore, we have revealed the SAFC emission mechanism via the pressure-tunable changes in the aggregation degrees and amount of hydrogen bonds involving 4 and P4VP chains. This work provides a good understanding for the morphology-property control of the self-assembled polymer composites in both microscopic and mesoscopic scales.

Self-sorting assembly of artificial building blocks

Self-assembly to build high-level structures, which is ubiquitous in living systems, has captured the imagination of scientists, striving to emulate the intricacy, homogeneity and versatility of the naturally occurring systems, and to pursue a similar level of organization in artificial building blocks. In particular, self-sorting assembly in multicomponent systems, based on the spontaneous recognition and consequent spatial aggregation of the same or interactive building units, is able to realize very complicated assembly behaviours, and usually results in multiple well-ordered products or hierarchical structures in a one-step manner. This highly efficient assembly strategy has attracted tremendous research attention in recent years, and numerous examples have been reported in artificial systems, particularly with supramolecular and polymeric building blocks. In the current review, we summarize the progress in recent years, and classify them into five main categories, based on their working mechanisms or principles. With the review of these strategies, we hope to provide not only some deep insights into this field, but also and more importantly, useful thoughts in the design and fabrication of self-sorting systems in the future.

Self-Assembled Polymeric Materials: Design, Morphology, and Functional-Oriented Applications

This Review focuses on the current research advances of the synthesis of various amphiphilic block copolymers (ABCs), such as conventional ABCs and newly-presented polyprodrug amphiphiles (PPAs), and the development of corresponding self-assemblies in selective solvents driven by the intermolecular interactions, like noncovalent hydrophobic interactions, π-π interactions, and hydrogen bonds, between ABCs or preformed small polymeric nanoparticles. The design of these assemblies is systematically introduced, and the diverse examples concerning the unique assembly structures along with the fast development of their exclusive properties and various applications in different fields were discussed. Possible perspectives on the existential challenges and glorious future were elucidated finally. We hope this review will provide a convenient way for readers to motivate more evolutional innovative concepts and methods to design next generation of novel polymeric nanoassemblies, and fill the gap between material design and practical applications. This article is protected by copyright. All rights reserved.

Amphiphilic random and random block terpolymers with PEG, octadecyl, and oleyl pendants for controlled crystallization and microphase separation

Amphiphilic random and random block terpolymers bearing PEG chains, crystalline octadecyl groups, and amorphous oleyl groups were designed to control crystallization and microphase separation in the solid state.

Design guide of amphiphilic crystalline random copolymers for sub-10 nm microphase separation

Sub-10 nm lamellar structures are efficiently constructed by the pendant microphase separation of amphiphilic crystalline random copolymers with broad molecular weight distribution that are obtained from free radical copolymerization.

Enzyme-responsive chiral self-sorting in amyloid-inspired minimalistic peptide amphiphiles

Self-sorting is a spontaneous phenomenon that ensures the formation of complex yet ordered multicomponent systems and conceptualizes the design of artificial and orthogonally functional compartments. In the present study, we envisage chirality-mediated self-sorting in β-amyloid-inspired minimalistic peptide amphiphile (C₁₀-l/d-VFFAKK)-based nanofibers. The fidelity and stereoselectivity of chiral self-sorting was ascertained by Förster resonance energy transfer (FRET) by the judicious choice of a pyrene (Py)-hydroxy coumarin (HOCou) donor-acceptor pair tethered to the peptide sequences. Seed-promoted elongation of the homochiral peptide amphiphiles investigated by AFM image analyses and Thioflavin-T (ThT) binding study further validated the chiral recognition of the l/d peptide nanofibers. Moreover, direct visualization of the chirality-driven self-sorted nanofibers is reported using super-resolution microscopy that exhibits enantioselective enzymatic degradation for l-peptide fibers. Such enantioselective weakening of the hydrogels may be used for designing stimuli-responsive orthogonal compartments for delivery applications.