Controllable self‐assembly of polystyrene‐block‐poly(2‐vinylpyridine)

Block copolymers can form various ordered structures by self‐assembly, and their composites with inorganic materials may give surprising properties. This review summarizes recent developments in the preparation, mechanism and application of various types of self‐assembly of polystyrene‐block‐poly(2‐vinylpyridine) (PS‐b‐P2VP). The focus of the review is on how to control the self‐assembly of the dynamic and ordered structure of PS‐b‐P2VP based materials by applying effective factors such as thermal annealing, solvent annealing, block composition and blending. Moreover, the combination of the self‐assembly of PS‐b‐P2VP and various nanoparticles, with potentials in drug delivery, sensors and catalysis, is highlighted. © 2018 Society of Chemical Industry     

Flexible conductive poly(styrene‐butadiene‐styrene)/carbon nanotubes nanocomposites: Self‐assembly and broadband electrical behavior

Flexible conductive nanocomposites with the ability of self‐assembly into well‐ordered structures are promising multifunctional materials for energy conversion and storage devices. In this work, flexible nanocomposites based on multi‐walled carbon nanotubes (MWCNTs) and poly(styrene‐butadiene‐styrene) (SBS) were obtained by solution casting, followed by a post‐annealing treatment, during 7 days at 110 °C, to enable the self‐organization of the SBS. The impact of the MWCNTs on the self‐assembly was studied by atomic force microscopy and Small angle X‐rays scattering, and the conductivity of these nanocomposites was analyzed over the broadband frequency range, that is, 10^?1–10⁶ Hz. The results revealed that the lower MWCNTs loadings (～0.2 v %) were the most suitable to achieve a conductive network through the SBS, maintaining self‐assembled domains. These domains include hexagonally packed cylinders and alternating lamellae. Furthermore, at loadings above 1 v %, the impact of further MWCNTs addition on the conductivity was marginal over the whole frequency range and the self‐assembly tendency was progressively reduced. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46650.     

Hydrogen‐bonded supramolecular polyurethanes

As a class of materials, supramolecular polymers represent an exciting area of advanced materials research. The combination of unique properties, easy synthesis and response to the environment or external and temporal stimuli makes them important as a focus for the next generation of materials. Understanding and manipulating the non‐covalent interactions leading to polymer assembly allows control over properties by selecting specific building blocks with well‐understood non‐covalent chemistry from an established toolkit. This allows assembly of defined and easily manipulated architectures, where physical characteristics similar to conventional high‐molecular‐weight polymers can be realized. Herein, we describe recent studies of the self‐assembly of polyurethane‐based supramolecular materials. © 2014 Society of Chemical Industry     

Aliphatic polycarbonate‐based polyurethane elastomers and nanocomposites. I. The influence of hard‐segment content and macrodiol‐constitution on bottom‐up self‐assembly

Aliphatic polycarbonate‐based polyurethane (PC‐PU) elastomers as well as their nanocomposites with organic‐modified clay (bentonite for organic system) were synthesized. Macrodiols (MD) (randomly copolymerized aliphatic PC‐glycols of molecular weight of about 2000: T5652, T4672, and T4692), hexamethylene diisocyanate, and butane‐1,4‐diol were used as starting materials. Solid‐state NMR and Fourier transform infrared spectroscopy, small‐angle X‐ray scattering, wide‐angle X‐ray diffraction, atomic force microscopy, and transmission electron microscopy were used for studying the bottom‐up self‐assembly of building units from the segmental level up that of organized structures of micrometer sizes. Contents of hard segments formed by the reaction of chain extender with diisocyanate plays a dominant role for the degree of ordering and related phenomena, while the MD chain has only limited effect on PC‐PU properties. The spectroscopy and scattering experiments suggest that bentonite particles incorporate well in the structure and promote the ordering of hard segment domains in PC‐PU matrix as compared with the nanofiller‐free analogue. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Sonication‐induced self‐assembly of polymeric porphyrin–fullerene: Formation of nanorings

In this article, we detail the sonication‐induced self‐assembly of polymeric porphyrin and fullerenes into distinct nanorings in solution form. The formation of these trenchant superstructures was the result of the delicate choice of different assembly protocols, solvents, and polymeric tails associated with porphyrin and fullerene. In this study, the sonication supposedly directed the lateral aggregation into uniform ring formation. The sonication time was found to be the key parameter in ring formation. Furthermore, the flexibility of polymeric arms and electronic interactions of porphyrin–fullerene gave rise to synergistically enhanced molecular interactions, and this resulted in discrete morphologies. Key optical data, including the absorption maxima of the complexes, and microscopic studies attested to the nature and morphology of the self‐assembled complexes. This introduction of polymeric arms and sonication protocols in the porphyrin self‐assembly was expected to allow the easy formation of diverse morphologies. Because of the facile fabrication process and uniform morphology, the resulting composite architectures might show promising applications in drug‐delivery and advance materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43537.     

Enhanced Combustion Characteristics of Bismuth Trioxide‐Aluminum Nanocomposites Prepared through Graphene Oxide Directed Self‐Assembly

We present a facile, spontaneous, and surfactant‐free method to controllably self‐assemble aluminum and bismuth trioxide nanoparticles through the introduction of graphene oxide as a self‐assembly directing agent. The self‐assembled nanocomposites demonstrate significant combustion performance improvements in comparison to randomly mixed aluminum and bismuth trioxide nanoparticles with enhanced pressure generation from 60 to 200 MPa, pressurization rate from 3 to 16 MPa μs⁻¹, burning rate from 1.15 to 1.55 km s⁻¹, and specific impulse from 41 to 71 s. The sensitivity of the self‐assembled aluminum and bismuth trioxide to electrostatic discharge was reduced by four orders of magnitude, without decreasing the combustion performance. Graphene oxide directed self‐assembly can be used to synthesize nanocomposites with diverse combustion properties and controlled ignition sensitivity, which lays the foundation for preparing multi‐functional, highly‐reactive, combustion systems in the future.     

Synthesis from Molecule into 3D Polyamide 6 Microspheres Stacked Polyhedrons via Self‐Assembly

Self‐assembly provides the basis for a procedure used to organize larger objects into regular, 3D microsphere stacked polyhedrons. A novel approach is described for the fabrication of 3D structured micrometer‐scale polyhedrons which are packed with nanosized spheres in the order of 400 nm by in situ polymerization using phase inversion technology. The extended polyhedrons can assemble into decimeter‐level ordered materials. The side length of an individual polyhedron can be effectively tuned from 10 to 100 µm through several ways. This method realizes directly self‐assembly from molecule to regular extended polyhedrons materials. The process is primarily based on in situ anion polymerization of lactam in two‐phase system whose self‐assembly is driven by hydrogen bonds' force and polyethylene glycol stepwise crystallization synergistically. The results suggest that this strategy for self‐assembly can be applied to design nonplanar complex geometric structure materials. In the future, polyhedrons packed with microspheres may be possible to build more complex 3D, self‐assembly device modules for advanced materials.     

Studies on self‐assembly and characterization of polyelectrolytes and organic dyes

Four polyelectrolyte complexes were formed through the self‐assembly of poly‐N‐ethyl‐N,N‐ dimethylamino ethyl methacrylate (PEDEM) and poly‐ N‐ethyl‐4‐vinylpyridinium (PEVP) cations with methyl orange (MO) and metanil yellow (MY) anions in water. The FTIR spectra showed that the assembly was formed chiefly through electrostatic force and hydrophobic interaction between polyelectrolytes and organic dyes without new bonds emerging. The fluorescence spectra revealed that the emission waves of the complexes of PEDEM‐MY and PEDEM‐MO in alcohol were blue‐shift in comparison with those of dyes in alcohol, and the emission waves of the PEVP‐MY and PEVP‐MO complexes in alcohol were red‐shift in comparison with those of dyes in alcohol. The structure of the complexes in solid state were also investigated by differential thermal analysis (DTA) and X‐ray diffraction experiments. It was proved that the complexes were new materials formed through weak interactions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 638–644, 2002     

Inkjet Printing Based Layer‐by‐Layer Assembly Capable of Composite Patterning of Multilayered Nanofilms

Surface modification involves developing a versatile thin film by combining the physical, chemical, or biological characteristics of the functional materials and can facilitate controlling material for desirable aims. Layer‐by‐layer (LbL) assembly can be used to create materials with controlled thicknesses and morphologies, diverse functionalities, and unique structures on any surface. However, despite the advantages of the LbL fabrication technique, there are limits to its application because it is a time‐consuming process and has difficulty controlling the shape of nanofilms. In addition, controlling the lateral organization is difficult because the preparation methods are based on one‐pot self‐assembly. In this study, a multilayered fabrication system is developed for the high‐throughput LbL assembly of nanofilms through inkjet printing. With various types of materials from synthetic polymer to graphene oxide to natural polymer and protein, the approach can tune the preparation of nanoscale multilayers with desired structures and shapes for specific applications on various substrates, including a silicon wafer, quartz glass, and cellulose‐based paper.     

Hydrogen bond‐mediated self‐assembly and supramolecular structures of diblock copolymer mixtures

This review summarizes recent advances in the preparation of hydrogen bonding block copolymer mixtures and the supramolecular structures they form through multiple hydrogen bonding interactions. Hydrogen bonding in block copolymer mixtures that form nanostructures and have unusual electronic, photonic and magnetic properties is a topic of great interest in polymer science. Combining the self‐assembly of block copolymers with supramolecular structures offers unique possibilities to create new materials with tunable and responsive properties. The self‐assembly of structures from diblock copolymer mixtures in the bulk state is readily controlled by varying the weight fraction of the block copolymer mixture and the copolymer composition; in solution, the morphologies are dependent on the copolymer composition, the copolymer concentration, the nature of the common solvent, the amount of the selective solvent and, most importantly, the hydrogen bonding strength. Copyright © 2008 Society of Chemical Industry     

Studies on self‐assembly and characterization of polyelectrolytes and organic dyes

Four polyelectrolyte complexes were formed through self‐assembly of poly‐N‐ethyl‐N,N‐(dimethylamino)ethyl methacrylate (PEDEM) and poly‐N‐ethyl‐4‐vinylpyridinium (PEVP) cations with methyl orange (MO) and metanil yellow (MY) anions in water. The FTIR spectra showed that the assembly was formed chiefly through electrostatic force and hydrophobic interaction between polyelectrolytes and organic dyes without new bonds emerging. The fluorescence spectra revealed that the emission waves of the complexes of PEDEM–MY and PEDEM–MO in alcohol were blue‐shifted in comparison with that of dyes in alcohol, and the emission waves of the PEVP–MY and PEVP–MO_ complexes in alcohol were red‐shifted in comparison with that of dyes in alcohol. The structure of the complexes in the solid state were also investigated by DTA and X‐ray diffraction experiments. It could be proved that the complexes were new materials formed through weak interactions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 369–374, 2003     

Peptide‐Thiophene Hybrids as Self‐Assembling Conductive Hydrogels

A bottom‐up approach is taken to confer multidimensional structure to conductive polymers by attaching thiophene monomers to peptides predicted to self‐assemble into a biomimetic, fibrous nanostructure. A library of 12 peptides containing covalently attached thiophene monomers are synthesized. Peptide sequences capable of robust self‐assembly and hydrogel formation in aqueous media are further polymerized in situ and the physical and electrical properties are characterized. The resulting hybrid materials have conductivities in the range of 10^?2 to 10^?3 S cm^?1 and possess moduli in the range of several tissue types, making them potential candidates for use in tissue engineering and bioelectronic applications.     

Macromolecular and supramolecular chirality: a twist in the polymer tales

Significant advances have been made recently in generating chiral polymer surfaces and materials using a range of methods such as block copolymer self‐assembly, layer‐by‐layer assembly and surface functionalization by polymer brushes. This paves the way for novel chiral materials that can harness and tailor chiral interactions for specific functionalities and properties in a range of biomedical and bioanalytical applications. This paper reviews these advances and speculates on the future of chiral surfaces. © 2013 Society of Chemical Industry     

Poly(9‐vinylcarbazole)/silver composite nanotubes and networks formed at the air–water interface

Silver‐nanoparticle‐doped poly(9‐vinylcarbazole) (PVK) nanocomposites were prepared via the reduction of Ag⁺ ions and the self‐assembly of PVK on AgNO₃ aqueous solution surfaces. The formed composite nanostructures depended strongly on the experimental temperature. Thick round disks of PVK surrounded by discrete Ag nanoparticles and/or with irregular holes formed at room temperature; nanotubes and micronetworks doped with Ag nanoparticles formed at about 30–40°C, and networks formed at higher temperature. Further investigation revealed that the nanotubes were transformed from thin round disks. The length of the PVK/Ag composite nanotubes were longer than 10 μm, and the average size of the embedded Ag nanoparticles was found to be about 3.5 nm. The composite networks were composed of round pores with diameters of several hundred nanometers and fine silver nanoparticles embedded in the thin polymer films that covered the pores. The formation of the nanotubes was a very interesting self‐assembly phenomenon of the polymer at the air–water interface that has not been reported before. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Ionic self‐assembly and characterization of a polysaccharide‐based polyelectrolyte complex of maleic starch half‐ester acid with chitosan

A novel polysaccharide‐based polyelectrolyte complex was formed via ionic self‐assembly (ISA) of a carboxylic derivative of starch, maleic starch half‐ester acid (MSA), with chitosan (CS) and precipitated from aqueous solution. Both Fourier transform infrared (FTIR) spectroscopy and elementary analysis results showed that there was CS in the complex. Thermogravimetric analysis (TGA) showed that the thermal resistance of the complex was higher than that of two components and the corresponding blend. X‐ray diffraction (XRD) analysis result revealed that the complex was amorphous, whereas its components were semi‐crystalline. In addition, the drug release behavior of the complex that contains 5‐fluorouracil behaved pH‐responsive. All the experimental results verified the complex was composed of MSA and CS, and also indicated that the driving force for the self‐assembly of the complex was predominantly the electrostatic interactions between two oppositely charged polyelectrolytes, cationic CS, and the anionic MSA. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Microwave‐Assisted Reversible Coordination‐Mediated Polymerization for Self‐Healing Hybrid Materials: RGO@PDA Simultaneous as Catalyst and Nanocomposites in One‐Pot

In this article, polydopamine (PDA) is efficiently adhered on the surface of graphene oxide (GO) by mussel‐inspired chemistry. The obtained reduced GO/PDA (RGO@PDA) nanocomposites are used for catalyzing reversible coordination‐mediated polymerization under microwave radiation. Well‐defined and iodine‐terminated polyacrylonitrile‐co‐poly(n‐butyl acrylate) (PAN‐co‐PnBA) is successfully fabricated by using RGO@PDA nanocomposites as catalysts. Importantly, green and novel strategy of PAN‐co‐PnBA‐type self‐healing nanocomposite materials is further fabricated with RGO@PDA as additive after polymerization as catalyst in one‐pot. As a reinforcement agent, RGO@PDA can also improve the mechanical and self‐healing properties of hybrid materials, which opens up a novel and green methodology for the preparation of self‐healing hybrid materials.     

Controllable reinforcement of stiffness and toughness of polypropylene via thermally induced self‐assembly of β‐nucleating agent

An easy approach was reported to achieve the simultaneous reinforcement and toughening of polypropylene (PP) via thermally induced self‐assembly of β‐nucleating agent (TMB‐5). The results showed that the processing temperatures dictated the solubility and self‐assembly of TMB‐5 in the polymer melts to determine the subsequent morphology development of PP. At low processing temperature, TMB‐5 did not dissolve into the polymer melt but remained original shape to induce PP to crystallize into spherulites so that it only promoted the formation of β‐form crystals to enhance the toughness of the samples. At high processing temperature, TMB‐5 gradually dissolved into the polymer melts. On cooling, the dissolved nucleating agent self‐assembled into high aspect ratio fibrils through intermolecular hydrogen‐bonding interactions. Due to a favorable matching between PP and TMB‐5, PP preferred to nucleate and grow orthogonally to the fibril axis and into oriented hybrid shish‐kebab morphology with rich β‐form crystals. Compared with isotropic spherulites, the anisotropic structure exhibited excellent properties of the β‐form crystal and shish‐kebab morphology to simultaneously improve the strength and toughness of TMB‐5‐modified PP samples. With the increasing processing temperature, more dissolved TMB‐5 was involved in the self‐assembly procedure to generate longer fibrils and induce more lamellae to grow on the surface. As a consequence, the anisotropy of the PP samples increased further, bringing out more improvements of the tensile strength. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40605.     

Directed self‐assembly by photostimulation of an amorphous semiconductor surface

A method for nanoscale directed self‐assembly is demonstrated that employs an amorphous semiconductor containing subcritical nuclei for crystallization. This strategy combines attractive features of top‐down and bottom‐up approaches by exploiting the self‐organization capabilities latent in amorphous materials, but in a way that can be controlled by optical or electron beam exposure tools. The method was demonstrated with amorphous TiO₂ deposited on silicon, heated to 270°C, and exposed to low‐level ultraviolet light. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Unique block molecules based on glycerol skeleton as C‐3 building blocks for liquid crystals formation by self‐assembly and their future potential for the “nano‐chemistry”

Studies on design of liquid crystalline block molecules with non‐conventional mesophase morphoplogies have been proposed by Tschierske and co‐workers. These block molecules have a rigid core, a lateral substituent, and an alkyl chain segmenting blocks from each other. Related to this, diglyceryl alkyl ethers found by us have glycerol as a rigid core, a lateral substituent, and an alkyl chain similar to the Tschierske design. These two cases are compared with each other with regard to the relationship between the molecular structure and the liquid crystalline morphologies and other properties. Recently, new soft materials suitable for liquid crystals exhibiting self‐assembly of phase‐segregated structures have been designed. Typical examples of such “block” molecules containing glycerol having a C‐3 building block include: (i) undecyl‐glycerylether‐ modified siloxane derivatives with a siloxane segment as the rigid core and alkyl chains with 2, 3‐dihydroxypropoxy group as a hydrophilic group at a lateral or terminal position of the siloxane segment; (ii) novel hyper branched dendrimers forming the basis of polyglycerol nanocapsules with a core‐shell molecular architecture; (iii) carbon nanotubes based on cyclodextrins (CDs); (iv) polymerizable amphiphilic diacetylene‐containing phospholipids suitable for construction of functional nanocomposites. This is done by self‐assembly and polymerization of diacetylene creating a “block molecular structure” with a polyacetylene chain as a rigid core segment, the lipid headgroups as the hydrophilic segment, and terminal flexible alkyl chains. On the basis of these results, future potential of block molecules as a soft building material for liquid crystalline structures was discussed.     

Liquid crystals from star‐like clusto‐supramolecular macromolecules

Supramolecular liquid crystals containing inorganic nanoclusters represent a promising avenue in the field of liquid crystals. The main motivation for developing these hybrid materials originates from the value‐added combination between functional properties of inorganic nano‐objects and the self‐assembly behavior of organic liquid crystal molecules. This review highlights the recent progress regarding nanocluster‐containing supramolecular liquid crystals. Important factors affecting the liquid crystalline behaviors are systematically described and summarized. The driving forces behind the molecular self‐assembly are discussed in depth. Finally, potential applications of the liquid‐crystalline nanohybrids are discussed. © 2014 Society of Chemical Industry