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Nanorods consisting of a polystyrene core and a poly(4-vinylpyridine) shell produced via the self-assembly route of comb-shaped supramolecules exhibit very poor mechanical properties. Adding a sufficient amount of poly(2,6-dimethyl-1,4-diphenyl oxide) introduces entanglements to the PS-core resulting in nanorods with much better properties, which can be used as templates for e.g. transition metal oxide tubes.

Involving supramolecular chemistry in self-assembling block copolymer systems enables design of macromolecular architectures that are challenging to obtain through conventional all-covalent routes. In this work we present supramolecular double-comb triblock terpolymers in which both outer blocks are able to interact with a surfactant via hydrogen bonding and thereby form a comb-shaped architecture upon complexation. While the neat triblock terpolymer only formed a triple lamellar morphology, multiple hierarchical structures were observed in these supramolecular comb-coil-comb triblock terpolymers by simply adjusting the surfactant concentration. Structures included spheres on tetragonally packed cylinders-in-lamellae and spheres on double parallel lamellae-in-lamellae, as evidenced by electron microscopy and X-ray scattering. Incorporation of a middle coil block thus allowed an even higher macromolecular complexity than the previously reported double-comb diblock copolymers.

The combination of asymmetric P4VP-b-PAPI diblock copolymers (i.e. f P 4 VP ≠ f PAPI ) and 3-NDP surfactants in hydrogen-bonded [poly(4-vinylpyridine)-block-poly(N-acryloylpiperidine)](3-nonadecylphenol)x (P4PA(3-NDP)x) supramolecular double-comb diblock copolymers could potentially result in rather interesting morphologies. However, plasticization of the copolymer and the ability of 3-NDP to crystallize were found to affect their self-assembly significantly. In general, for high comb densities x, the complex's tendency to crystallize and its preference to form a flat interface dominated microphase separation. Lower values of x on the other hand gave uneven distribution of 3-NDP, resulting in a higher glass transition temperature of the P4VP block. Crystallization of 3-NDP's aliphatic tails was therefore in most cases restricted to the preferential PAPI microdomains, thereby maintaining the large length scale block copolymer morphology that was already present in the melt. Such behavior is identical to self-assembly of linear semicrystalline diblock copolymers, as in these type of systems structure formation depends on the segregation strength and relative magnitude of the order-disorder transition ( T ODT ), T g and T c , leading to mechanisms like confined crystallization or breakout.

Involving supramolecular chemistry in self-assembling block copolymer systems enables design of complex macromolecular architectures that, in turn, could lead to complex phase behavior. It is an elegant route, as complicated and sensitive synthesis techniques can be avoided. Highly grafted double-comb diblock copolymers based on symmetric double hydrogen bond accepting poly(4-vinylpyridine)-block-poly(N-acryloylpiperidine) diblock copolymers and donating 3-nonadecylphenol amphiphiles are realized and studied systematically by changing the molecular weight of the copolymer. Double perpendicular lamellae-in-lamellae are formed in all complexes, independent of the copolymer molecular weight. Temperature-resolved measurements demonstrate that the supramolecular nature and ability to crystallize are responsible for the formation of such multiblock-like structures. Because of these driving forces and severe plasticization of the complexes in the liquid crystalline state, this supramolecular approach can be useful for steering self-assembly of both low-and high-molecular-weight block copolymer systems.

The formation of unusual multilayered parallel lamellae-in-lamellae in symmetric supramolecular double-comb diblock copolymers is presented. While keeping the concentration of surfactant fixed, the number of internal layers was found to increase with molecular weight M up to 34 for the largest block copolymer. The number of internal structures n was established to scale as M0.67 and therefore enables easy design of such structures with great precision.

Block copolymers are known to spontaneously form ordered structures at the nano-to mesoscale. Although the number of different morphologies is rather limited in diblock copolymer systems, their phase behavior becomes increasingly more complex with each additional building block. Synthesis of such all-covalent materials is, however, a very challenging task. By moving to supramolecular chemistry these preparation methods can be avoided while maintaining the same kind of macromolecular complexity. After a brief introduction, this feature article will provide a selection of the most recent work performed in the field of self-assembling supramolecular block copolymer-containing materials. By careful choice of both the copolymer and, in many cases, the small organic surface active compound, fascinating morphologies can appear in supramolecular comb-shaped block copolymers. Several examples will be discussed, while a number of functional materials (e.g. thermal, optical, electronic) originating from these type of complexes will be addressed as well.

To provide a faster calculation of the block copolymer phase diagrams a simplified version of the self-consistent field theory (SCFT) is proposed. Multi-component block copolymers with interactions between repeated units described by the -parameters satisfying the Hildebrand conditions are studied. This case is shown to correspond to a degeneration within the framework of the general SCFT approach. Remarkably, the degenerated thus multi-component block copolymers admit two-component only SCFT description. The procedure presented is applied to gradient copolymers considered as a limiting case of multi-component copolymers obeying Hildebrand conditions, the lengths of the blocks vanishing and the number of different kinds of repeated monomers tending to infinity. Finally, a melt of symmetric triblock copolymers blurred into a gradient copolymer is studied and corresponding phase diagrams are calculated.

Linear poly(4-tert-butoxystyrene)-b-poly(4-vinylpyridine) (PtBOS-b-P4VP) diblock copolymers are synthesized using reversible addition-fragmentation chain transfer polymerization. The self-assembly of four different PtBOS-b-P4VP diblock copolymers is studied using small-angle X-ray scattering and transmission electron microscopy and a number of interesting observations are made. A tBOS(62)-b-4VP(28) diblock copolymer with a weight fraction P4VP of 0.21 shows a disordered morphology of P4VP spheres with liquid-like short-range order despite an estimated value of chi(N) of the order of 50. Increasing the length of the 4VP block to tBOS(62)-b-4VP(199) results in a diblock copolymer with a weight fraction P4VP of 0.66. It forms a remarkably well-ordered lamellar structure. Likewise, a tBOS(146)-b-4VP(120) diblock copolymer with a weight fraction P4VP of 0.33 forms an extremely well-ordered hexagonal structure of P4VP cylinders. Increasing the P4VP block of this block copolymer to tBOS(146)-b-4VP(190) with a weight fraction P4VP of 0.44 results in a bicontinuous gyroid morphology despite the estimated strong segregation of chi N congruent to 150. These results are discussed in terms of the architectural dissimilarity of the two monomers, characterized by the presence of the large side group of PtBOS, and the previously reported value of the interaction parameter, chi congruent to 0.39, for this polymer pair.

The self-assembly of the hydrogen-bonded complexes between poly(p-hydroxystyrene) (PpHS) and 4-alkylpyridine amphiphiles is studied using infrared spectroscopy, differential scanning calorimetry, polarized optical microscopy, transmission electron microscopy and small-and wide-angle X-ray scattering. Interesting differences are observed with the well-studied inverted system of poly(4-vinylpyridine) and alkylphenol amphiphiles. When the alkyl tails of the 4-alkylpyridine amphiphiles are long enough, 19 and 21 respectively, an ordered lamellar structure is formed on cooling where the ordering and crystallization of the alkyl tails occur quasi simultaneously. For a shorter alkyl tail of length 17 no ordered structure is formed. This is quite different from the inverted P4VP/alkylphenol systems, where already for an alkyl tail of length 15, i.e., pentadecylphenol, an ordered structure is formed below ca. 55 degrees C, followed by crystallization of the alkyl tails at ca. 20 degrees C. This can be attributed to the possibility of (intramolecular) hydrogen bond formation of PpHS. (C) 2016 Elsevier Ltd. All rights reserved.

Controlled radical polymerization of 4-vinylpyridine (4VP) and N-acryloylpiperidine (API) by the RAFT process allowed preparation of well-defined double hydrogen bond accepting P4VP-b-PAPI diblock copolymers. The miscibility of this new monomer pair was studied via a random copolymer blend approach and resulted in a Flory–Huggins interaction parameter χ4VP,API ≈ 0.03, which is higher than the commonly used styrene/MMA couple, but lower compared to styrene/isoprene. This value was found to support the bulk phase behavior of a series of diblock copolymers as evidenced by SAXS and TEM. Highly ordered structures, including cylinders, lamellae and spheres, were identified in these materials, even in diblocks of higher molecular weight and broader distribution, while a disordered morphology was indeed observed in a symmetric, low molecular weight analogue.

The unique mechanical performance of nacre, the pearly internal layer of shells, is highly dependent on its complex morphology. Inspired by the structure of nacre, the fabrication of well-ordered layered inorganic-organic nanohybrids is presented herein. This biomimetic approach includes the use of a block copolymer template, consisting of hydrophobic poly(vinylidene fluoride) (PVDF) lamellae covered with hydrophilic poly(methacrylic acid) (PMAA), to direct silica (SiO2) mineralization. The resulting PVDF/PMAA/SiO2 nanohybrid material resembles biogenic nacre with respect to its well-ordered and layered nanostructure, alternating organic-inorganic phases, macromolecular template, and mild processing conditions. A biomimetic approach toward well-ordered laminated organic-inorganic nanocomposites. The hybrid material is mimicking the architecture and natural processing of nacre.

A double-comb diblock copolymer was constructed experimentally using a double supramolecular approach. Addition of 3-nonadecylphenol (3-NDP) amphiphiles to a symmetric, double hydrogen bond accepting poly(4-vinylpyridine)-block-poly(N-acryloylpiperidine) (P4VP-b-PAPI) diblock copolymer resulted in microphase separation on both the block copolymer and polymeramphiphile level. Variation of the comb density x in these [P4VP-b-PAPI](3-NDP)x supramolecular complexes gave rise to several unique hierarchical nanostructures. For high comb densities (x = 0.8 - 1.2) double perpendicular lamellae-in-lamellae were observed, while lowering the density to x = 0.5 resulted in a double parallel lamellar morphology as demonstrated by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Further decreasing the concentration of 3-NDP (x = 0.3) caused the complex to self-assemble into cylinders-in-lamellae, while for x = 0.1 3-NDP only serves as a plasticizing agent. The phase transitions identified as a function of x are all in excellent agreement with our previously performed theoretical analysis.

The fabrication of nanoporous poly(vinylidene fluoride) (PVDF) and PVDF/nickel nanocomposites from semicrystalline block copolymer precursors is reported. Polystyrene-block-poly(vinylidene fluoride)-block-polystyrene (PS-b-PVDF-b-PS) is prepared through functional benzoyl peroxide initiated polymerization of VDF, followed by atom transfer radical polymerization (ATRP) of styrene. The crystallization of PVDF plays a dominant role in the formation of the block copolymer structure, resulting in a spherulitic superstructure with an internal crystalline-amorphous lamellar nanostructure. The block copolymer promotes the formation of the ferroelectric beta-polymorph of PVDF. Selective etching of the amorphous regions with nitric acid leads to nanoporous PVDF, which functions as a template for the generation of PVDF/Ni nanocomposites. The lamellar nanostructure and the beta-crystalline phase are conserved during the etching procedure and electroless nickel deposition.

The double gyroid network morphology has been the focus of extensive research efforts as one of the most appealing block copolymer structures for practical applications. We performed an extensive study of the phase behavior of the supramolecular complex PS-b-P4VP(PDP)(x) to develop a systematic route to its double gyroid morphology. The morphological characterization of complexes was accomplished by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). Several compositions with the cubic Ia(3)over bard symmetry were found in a narrow region between the lamellar and the cylindrical phase. Experimental TEM images were compared to computer simulations of projections through multiple gyroid planes. Typical gyroid patterns "double wave" and "wagon wheel" were regularly found. The size of the gyroid unit cell was calculated from the SAXS data. The lattice parameter could be varied (from ca. 70 to 125 nm) by altering the molar mass of the block copolymer precursors. A number of complexes were found to exhibit characteristic biphasic morphologies coexisting lamellar and gyroid phase or gyroid and cylindrical phase. Finally, gyroid complexes with different relative PDP ratios were obtained which provides the opportunity to generate nanoporous structures with tunable porosities by dissolving the amphiphiles.

We revisit the idea of the existence of the ordered block copolymer phase possessing diamond symmetry Fd (3) over barm (space group No. 227), which was first put forward within the framework of the strong segregation approach. For this purpose we study the order-disorder and order-order transitions in molten two-scale multiblock copolymers A(mN/2)(B(N/2)A(N/2))(n)B-mN/2 via the pseudo-spectral numerical procedure of the self-consistent field theory (SCFT). The phase diagram in the plane (f(C), (chi) over tilde), where f(C) = n/(m + n) and (chi) over tilde = chi N(m + n) is the effective energetic Flory-Huggins parameter, is built and some accompanying quantities are analyzed. Near the order-disorder transition line the phase diagram contains the regions where the lamellar, alternating gyroid, diamond and simple cubic phase, respectively, exist. With an increase of the degree of segregation, the diamond phase is replaced by a tetragonal array of cylinders (simple square) phase, which agrees with the preceding results obtained within the Leibler-like weak segregation theory, and with the SCFT calculations for a physically similar melt of linear ABC triblock copolymers with a non-selective middle block. Thus, the diamond morphology in the system under study is shown to exist as an essentially weak or moderately (not strongly) segregated phase. The ways to visualize the patterns of ordering in such morphologies are discussed. A new quantity (topological permeability) to characterize the transport properties in 3D bicontinuous morphologies is introduced and first calculated for real block copolymer ordered morphologies. Some implications of the results obtained for the design of the block copolymer thin films with improved permeability are discussed.

Supramolecular complexes of a poly(tert-butoxystyrene)-block-polystyrene-block-poly(4-vinylpyridine) triblock copolymers and less than stoichiometric amounts of pentadecylphenol (PDP) are shown to self-assemble into a core-shell gyroid morphology with the core channels formed by the hydrogen-bonded P4VP(PDP) complexes. After structure formation, PDP was removed using a simple washing procedure, resulting in well-ordered nanoporous films that were used as templates for nickel plating.

Four different poly(tert-butoxystyrene)-b-polystyrene-b-poly(4-vinylpyridine) (PtBOS-b-PS-b-P4VP) linear triblock copolymers, with the P4VP weight fraction varying from 0.08 to 0.39, were synthesized via sequential anionic polymerization. The values of the unknown interaction parameters between styrene and tert-butoxystyrene and between tert-butoxystyrene and 4-vinylpyridine were determined from random copolymer blend miscibility studies and found to satisfy 0.031 < χS,tBOS < 0.034 and 0.39 < χ4VP,tBOS

Thin films of comb-shaped supramolecules have been used to create arrays of spatially separated ordered nanorods with a polystyrene core and a poly(4-vinyl pyridine) corona. Room temperature pulsed laser deposition of a uniform layer of lead titanate on top of these nanorod arrays and Subsequent heating to 565 degrees C, far above the degradation temperature of the block copolymer nanorods, resulted in ordered arrays of ferroelectric lead titanate nanoparticles, due to the evaporation of the polymer rods and the SrTiO(3) substrate-nucleated crystallization of the lead titanate. The spacing in between the ordered cylinders of the template and the nonselective nature of the coating procedure sets the method apart from conventional block copolymer templating techniques involving parallel cylindrical structures. Given the nonselective nature of the coating method, this template procedure is applicable for a large variety of inorganics.

Polypyrrole has been chemically synthesized on thin film nanostructures obtained from comb-shaped supramolecules of polystyrene-block-poly(4-vinyl pyridine) (PS-b-P4VP) hydrogen bonded with pentadecylphenol (PDP). PDP was washed from thin films of cylindrical and lamellar self-assembled combcopolymer systems, which resulted in removal of the upper layers of microdomains, leaving single cylindrical and lamellar layers covering a substrate, with P4VP segregated at the bottom as well as at the free air interface. This P4VP was complexed with Cu(2+) ions, after which chemical oxidation polymerization of pyrrole resulted in a thin polypyrrole layer covering the nanostructured block copolymer. The use of a catalytic amount of bipyrrole greatly improved the quality of the obtained product. The conductivity was measured to be similar to 0.7 S cm(-1). (C) 2009 Elsevier Ltd. All rights reserved.

Random copolymers of styrene and 4-vinylpyridine P(S(1-x)-co-4VP(x)) were synthesized to study the effect of the random copolymer "repulsion" on the self-assembly in hydrogen-bonded complexes with pentadecylphenol (one PDP molecule per 4VP group). The major trends observed as a function of the fraction of styrene monomers 1 - x in the random copolymer are a decrease in order-disorder transition temperature, T(ODT), and a decrease in the periodic length scale of the ordered lamellar state. The lower T(ODT) results from a partial shielding in the disordered state of the highly unfavorable styrene/4-vinylpyridine interactions by the PDP alkyl tails. The reduced layer thickness in the ordered state is due to the relaxation into a more coil-like conformation of the alkyl tails of the PDP amphiphiles, made possible by the presence of styrene units. The self-assembly properties of P(S(1-x)-co-4VP(x))(PDP)(1.0) are compared with those of the lamellar self-assembled homopolymer-based P4VP(PDP)(x) system, where x denotes the number of PDP molecules per 4VP repeat unit. As in P(S(1-x)-co-4VP(x))(PDP)(1.0), in P4VP(PDP)(x) also only a fraction x of the total number of monomers of the macromolecule may potentially hydrogen bond with PDP molecules at any given instant. In contrast to P(S(1-x)-co-4VP(x))(PDP)(1.0), for P4VP(PDP),, however, the long period is found to increase for decreasing values of x.

A simple theoretical analysis of the lamellar-in-lamellar self-assembled state of ternary C-b-(B-b-A)(m)-b-B-b-C multiblock copolymer melts in the strong segregation limit is presented using the Alexander de Gennes approximation. For a given value of m, the influence of the chain length of the various blocks and the value of the Flory-Huggins chi(AB) and chi(BC) interaction parameters on the number k of internal domains is discussed in detail. The theoretically predicted tendencies are corroborated by computer simulations using the dissipative particle dynamics technique.

The terrace formation behavior of chloroform vapor annealed thin films of asymmetric, low molecular weight comb-shaped supramolecules consisting of a short polystyrene (PS) block and a long supramolecular block of poly(4-vinylpyridine) (P4VP) hydrogen bonded with pentadecylphenol (PDP) on silicon oxide (SiO2) was examined with atomic force microscopy. During annealing, PS microphase separated from the disordered P4VP(PDP) comb, resulting in the formation of terraces of parallelly oriented microdomains of PS in a matrix of P4VP. Upon evaporation of the solvent, the P4VP(PDP) combs dropped below their order-disorder transition, and formed alternating layers of P4VP and PDP, which for high P4VP(PDP) fractions were also oriented parallel to the substrate. This resulted in terraces of the short P4VP(PDP) length scale within terraces of the PS-P4VP long length scale. Washing away PDP from the thin films with ethanol provided an effective means of studying the morphology of the lowest terrace of the thin films and, for a particular system, also resulted in a uniform monolayer of cylinders with a PS core and a P4VP corona.

Using atom transfer radical polymerization (ATRP), poly(tert-butyl methacrylate-b-styrene-b-4-vinylpyridine) or PtBMA-b-PS-b-P4VP linear triblock copolymers were synthesized. Different homopolymer and diblock copolymer macroinitiators were used for different block copolymerizations. For a selected triblock copolymer the self-assembly was studied with transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and thermal analysis. Indications were found for a core−shell hexagonal ordering of coaxial cylinders with P4VP cylinders separated from the PtBMA matrix phase by a PS shell layer. To further support this, the interaction parameter between styrene and tBMA was investigated by a random copolymer blend miscibility study on blends of P(S-co-tBMA) random copolymers with PS and found to satisfy 0.08 < χS,tBMA < 0.10.

Para-substituted alkyl and alkoxy phenylazophenols (PAP's) have been synthesized and used as hydrogen-bonded side chains for poly(4-vinylpyridine)-based comb-shaped supramolecules akin to the well-studied poly (4-vinylpyridine)/pentadecyl phenol systems. In this paper we report the self-assembly of these new materials as investigated by DSC and simultaneous SAXS/WAXS. The systems exhibit smectic ordering with a periodicity in the range of 3.0-4.2 nm. The periodicity length scale, the order-disorder transition temperature (T-ODT), and the glass transition temperature T-g of the self-assembled systems all increase with increasing alkyl chain length. The correlation between T-ODT and T-g observed is argued to be the consequence of the increasing segregation in the self-assembled systems with increasing alkyl tail length of the amphiphiles.

The phase behavior and terrace formation of solvent (chloroform) vapor annealed thin films of asymmetric comb-shaped supramolecules consisting of a polystyrene (PS) block and a supramolecular block of poly(4-vinylpyridine) (P4VP) hydrogen bonded with pentadecylphenol (PDP) on silicon oxide (SiO2) were examined. P4VP(PDP) was found to be present at the SiO2 interface as well as the air interface, implying symmetric boundary conditions. Because of the inherent change in composition by swelling in a selective solvent, the morphology of a lamellar film Could be changed to cylindrical by swelling at different vapor pressures of chloroform vapor. Swelling at a specific vapor pressure at the phase boundary between lamellar and cylindrical resulted in noncommon terrace formation behavior. The lowest terrace consisted of two wetting layers forming one lamella, the second terrace contained perpendicular lamellae, and the highest terrace consisted of parallel P4VP(PDP) cylinders. The results are presented in a morphology diagram as a function of film thickness and composition.

A detailed SAXS study of self-assembled block copolymer-based supramolecules composed of a polyisoprene-block-poly(2-vinylpyridine) diblock copolymer and octyl gallate that is hydrogen bonded to the vinylpyridine block in a stoichiometric ratio is presented. The changes in the system morphology with temperature are investigated both at rest and under oscillatory shear. In between the lamellar-to-cylindrical transition a new intermediate structure, identified as a deformed hexagonal structure (DHS), was observed. Being at rest the DHS is argued to consist of ellipsoidal cylinders that adopt a more regular circular shape when the sample is subjected to shear. These results are discussed in terms of hydrogen bond breaking under shear.

The phase behavior of blends of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) with random copolymers of styrene and 2-vinyl pyridine, Poly(S-co-2VP), as well as with random copolymers of styrene and 4-vinyl pyridine, Poly(S-co-4VP), has been investigated in order to estimate the values of the Flory–Huggins parameters χ PPO , 2 VP and χ PPO , 4 VP between PPO and 2-vinyl pyridine, resp. 4-vinyl pyridine. Using previously estimated values for the Flory–Huggins parameters 0.09 χ S , 2 VP 0.11 and 0.30 χ S , 4 VP 0.35 , together with the literature value of χ S , PPO = − 0.043 , the phase behavior observed as a function of the copolymer composition results in 0.11 ≤ χ PPO , 2 VP ≤ 0.12 and 0.46 ≤ χ PPO , 4 VP ≤ 0.48 . Insight in the interaction between PPO and poly(vinyl pyridine) is of considerable interest for several nanotechnology developments, since PPO is used to improve the mechanical properties of e.g. PS-block-P4VP nanorods.

Previously we demonstrated hierarchical self- assembly and mesoporosity in electrospun fibers using selected polystyrene- block- poly(4- vinylpyridine) (PS- b- P4VP) diblock copolymers with hydrogen- bonded 3- n- pentadecylphenol (PDP), which rendered distorted spherical P4VP(PDP)(1.0) domains within the PS matrix, internal lamellar order within the P4VP(PDP)(1.0) domains, and allowed distorted spherical pores by removing PDP (Adv. Mater. 2005, 17, 1048). Here we study whether the internal structure of electrospun fibers can be systematically tailored by varying the compositions of PS- b- P4VP(PDP)(1.0). We expect these complexes to be feasible choices to combine electrospinning and self- assembly, as relatively high molecular weight block copolymers are useful for electrospinning, and enhanced structure formation due to plasticization by the amphiphilic PDP was expected. Not surprisingly, the self- assembled structures of the as- prepared fibers were less perfect than those in the corresponding well- annealed bulk materials. Compositions that show spherical self- assembly of P4VP(PDP)(1.0) within the PS matrix in bulk lead to distinct and elongated worm- like P4VP(PDP)(1.0) domains within the PS matrix in electrospun fibers. More symmetric compositions, which showed lamellar self- assembly in bulk, lead to structures where both PS and P4VP(PDP)(1.0) domains were worm- like and elongated in a relatively symmetric manner. Finally, compositions which in bulk showed self- assembly of PS spheres within the P4VP(PDP)(1.0) matrix, lead to separate distorted PS domains in the P4VP(PDP)(1.0) matrix. Additionally, SAXS measurements suggest a lamellar structure within the P4VP(PDP)(1.0) domains. As electrospinning is a facile method to prepare mesoscale fibers, and it is known that the amphiphiles can be removed from the hierarchical assemblies, the present method offers the potential to tune the internal porosity of the fibers for e. g. release and absorption purposes.

We studied coil-globule transitions in stiff-chain amphiphilic macromolecules via computer modeling and constructed phase diagrams for such molecules in terms of solvent quality and persistence length. We showed that the shape of the phase diagram essentially depends on the macromolecule degree of polymerization. Relatively short amphiphilic molecules always form a spherical globule in a poor solvent, and the coil-globule transition includes one or two intermediate conformations, depending on the chain's stiffness. These are a disk-like globule in case of high enough Kuhn segment length, and a pearl necklace-like structure of spherical micelles and a disk-like globule in case of relatively flexible chains. The phase diagram of a long stiff amphiphilic chain was found to be more complex still. Thus three specific regions can be distinguished in the poor solvent region, depending on the chain stiffness. These correspond to a cylindrical globule without any specific backbone ordering, a cylindrical globule containing blobs with collagen-like ordering of the chain, and co-existence of collagen-like and toroidal globules. in the intermediate transition region in this case, apart from the pearl necklace-like conformations with spherical micelles, necklace conformations can be also observed where the polymeric chain has collagen-like ordering within each bead.

The self-assembly of P4VP(3-PDP)(1.0) and P4VP(4-NDP)(1.0) supramolecular comb-shaped copolymers has previously been shown to have very interesting thermal properties, since besides crystallization of 3-PDP/4-NDPs alkyl tails, an additional order-disorder transition (ODT) was observed as well. In order to get a better insight into the processes involved and the parameters that determine this behavior, a library consisting of differently substituted n-alkylphenol surfactant molecules was synthesized. A general trend was found in the stoichiometric P4VP-based complexes. As expected, both the melting point and long period of the lamellar structure increased with a longer tail length, while surprisingly T-ODT only depended on the position of the hydroxyl group. Its magnitude is assumed to be directly related to the strength of hydrogen bonding, which is highest for the sterically least hindered surfactants (para). Additionally, critical behavior was discovered in meta-substituted complexes: a large reduction in both T-m and T-ODT was observed for a 13 methylene unit long amphiphile, while crystallization of the alkyl tails determined the self-assembly in P4VP(3-henicosylphenol)(1.0).

Hydrogen-bonding amphiphilic low molecular weight plasticizing compounds to one block of diblock copolymers to form supramolecular comblike blocks leads to hierarchical self-assembly at the block copolymer (long) and amphiphile (short) length scales, in which lamellar-in-lamellar order and the related phase transitions have previously been shown to allow thermal switching of electrical and optical properties [Science 1998, 280, 557; Nat. Mater. 2004, 3, 872]. In this work other hierarchies and phase transitions are systematically searched, a particular interest being hierarchies containing gyroid structures and the related order-order transitions. Polymeric supramolecular comb-coil diblock copolymers consisting of a polystyrene (PS) coillike block and a supramolecular comblike block based on poly(4-vinylpyridine) (P4VP) are used, where the pyridines are either directly hydrogen bonded with 3-pentadecylphenol (PDP), i.e., PS-block-P4VP(PDP)(1.0), or first protonated with methanesulfonic acid (MSA) and then hydrogen bonded to PDP, i.e., PS-block-P4VP(MSA)(1.0)(PDP)(1.0). In this way the comblike block can be noncharged or charged. The morphologies were determined using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) at different temperatures. In the case of PS-block-P4VP(PDP)(1.0), all classical diblock copolymer morphologies were observed at room temperature, where the P4VP(PDP)(1.0) domains contain an additional lamellar structure due to the supramolecular comblike blocks. Here we report novel gyroid and hexagonal perforated layer morphologies, i.e., where the PS and P4VP(PDP)(1.0) blocks form gyroid or hexagonal perforated layer order and the P4VP(PDP)(1.0) domains have an internal lamellar order. Heating past ca. T = 60 degrees C causes an order-disorder transition within the P4VP(PDP)(1.0) domains. Further heating leads to gradually reduced hydrogen bonding strength, and importantly PDP becomes soluble in PS at T > ca. 120 degrees C. At such temperatures PDP is found in both the P4VP and PS domains, thus leading to changes in the relative volume fractions of the domains, which in turn leads to order-order transitions. In PS-block-P4VP(MSA)(1.0)(PDP)(1.0), typically lamellar and cylindrical block copolymeric structures were observed, where there was an additional internal lamellar order within the P4VP(MSA)(1.0)(PDP)(1.0) domains. Coincidentally, an order-disorder transition within the P4VP(MSA)(1.0)(PDP)(1.0) domains takes place at T = ca. 125 degrees C. Above that temperature, PDP is in both PS and P4VP(MSA)(1.0) domains, but most interestingly at ca. T > 175 degrees C PDP becomes a nonsolvent for P4VP(MSA)(1.0) and it is therefore expelled to predominantly to the PS domains. This manifests as an order-order transition. All samples exhibit at least two thermoreversible order-order transitions, and some of them show even five consecutive self-assembled phases as a function of temperature. Besides being amphiphilic, PDP can also be regarded as a plasticizer, i.e., relatively nonvolatile solvent, for the P4VP, PS, and P4VP(MSA)(1.0) with characteristic phase behaviors.This, in combination with the comb-coil diblock copolymer composition and the reversibility of the hydrogen bonding, enables to achieve thermoreversible transition sequences that are not easily accessible only by changing the Flory-Huggins interaction parameter chi by temperature, for example trnsitions from a lamellar to spherical structure. The combination of phase behaviors of self-assembly and polymer/plasticizer mixtures allows new structural hierarchies and phase transitions that may lead to new types of responsive materials.

The results of a detailed theoretical investigation of the phase behavior of A(m)-b-(B-b-A)(n) multiblock copolymer melts are presented for the special case of m = 20 and n = 10. The presence of two strongly different molecular length scales results in the formation of a large-length-scale lamellar structure of alternating A(20) and (B-b-A)(10) layers on cooling. On further cooling, the (B-b-A)(10) layers subsequently transform internally into small-length-scale layers of the A and B blocks: a lamellar-in-lamellar morphology. The final structure consists of an alternation of one "thick" layer and seven "thin" layers and compares favorably with recent experimental results of Matsushita and co-workers on slightly different systems.

Electrically conducting hexagonally self-assembled nanostructures of poly(aniline) (PANI) protonated with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) and hydrogen bonded with resorcinol (res), 4-ethylresorcinol (C2res) or 4-hexylresorcinol (C6res) are studied. Small-angle X-ray scattering (SAXS) of PANI(AMPSA)0.5(Cnres)y with y = 0, ..., 1.5 indicate cylindrical self-assembly in all cases, and the long period depends on n and y. Addition of Cnres leads to plasticization and an increase of conductivity of up to ca. 4 orders of magnitude until saturation is achieved upon approaching y = 1. Simultaneously, the temperature gradient of the conductivity dσ/dT near the room temperature changes from positive to negative, which is reminescent to a transition from a thermally activated hopping-type to a more “metallic-like” behavior. It is suggested that, upon complexation with especially res and C2res, the PANI chains become progressively more confined in cylinders suggesting their stretching. Overall ali...

Several alkyl side chains are bonded to each polymeric repeat unit using both coordinated ligands and electrostatically bound counterions to directly control the interface curvature of the self‐organized structures. 2,6‐Bis(octylaminomethyl)pyridine is Zn‐coordinated to poly(4‐vinylpyridine) (P4VP) with dodecylbenzenesulfonate (DBS) counterions, leading to multicomb polymeric supramolecules, poly[(4VP)Zn(2,6‐bis(octylaminomethyl)pyridine)(DBS)2]. Coordination is evidenced by infrared spectroscopy and visualized by quantum chemical calculations. The amorphous hexagonal self‐organized structures are characterized using X‐ray measurements.

The phase behavior of a melt of monodisperse rod-coil diblocks is studied. We derive a Landau free energy functional for both a compositional and a nematic order parameter. The excluded volume interaction between the rod blocks is modeled by an attractive Maier-Saupe interaction. The incompatibility between rod- and coil blocks is modeled by the usual Flory-Huggins interaction. For a large volume fraction of the rods, a transition from isotropic to nematic to smectic C is observed upon decreasing the temperature, whereas for small rod volume fraction, spherical, hexagonal, and lamellar structures prevail. In the smectic C phase, the rod orientation angle with respect to the lamellar normal increases rapidly from 35 to 40 degrees close to the nematic/smectic-C phase boundary to values between 45 and 55 degrees., Comment: 33pp. 8 figs (REVTeX). Typos in Eqs.(10), (28), and (B.36)-(B.39) corrected

Comb-shaped supramolecules are constructed using flexible polymers and semi-rigid conjugated undoped or doped conjugated polymers upon complexing Zinc dodecyl benzene sulphonate, Zn(DBS) 2 . Self-organized nanostructures are formed in the bulk due to competing attractive interactions (coordination or water mediated hydrogen bonding) and repulsive polar/nonpolar interactions, showing characteristic long periods of ca. 30 A.

Poly(vinylidene fluoride) (PVDF) has reached the second largest production volume of fluoropolymers in recent years, and its popularity can be ascribed to high thermal stabil- ity and chemical inertness combined with its ferroelectric behavior. Copolymerization of vinylidene fluoride with other monomers leads to a wide variety of products with modified or improved properties. Besides commercially available fluori- nated random copolymers, well-defined block-, graft, and alter- nating copolymers based on PVDF received more attention in recent years. PVDF-containing block copolymers that may self- assemble into well-ordered morphologies are of particular interest, being potential precursors for functional nanostruc- tured materials applicable in membranes and electronics. This Highlight provides an overview of the routes developed towards these materials via conventional and controlled poly- merization techniques. In addition, it discusses their nano- scopic phase behavior and current and potential applications. V C 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2861-2877

Nanoporous metal foams possess a unique combination of properties - they are catalytically active, thermally and electrically conductive, and furthermore, have high porosity, high surface-to-volume and strength-to-weight ratio. Unfortunately, common approaches for preparation of metallic nanostructures render materials with highly disordered architecture, which might have an adverse effect on their mechanical properties. Block copolymers have the ability to self-assemble into ordered nanostructures and can be applied as templates for the preparation of well-ordered metal nanofoams. Here we describe the application of a block copolymer-based supramolecular complex -polystyrene-block-poly(4-vinylpyridine)(pentadecylphenol) PS-b-P4VP(PDP) - as a precursor for well-ordered nickel nanofoam. The supramolecular complexes exhibit a phase behavior similar to conventional block copolymers and can self-assemble into the bicontinuous gyroid morphology with two PS networks placed in a P4VP(PDP) matrix. PDP can be dissolved in ethanol leading to the formation of a porous structure that can be backfilled with metal. Using electroless plating technique, nickel can be inserted into the template's channels. Finally, the remaining polymer can be removed via pyrolysis from the polymer/inorganic nanohybrid resulting in nanoporous nickel foam with inverse gyroid morphology.

Double-crystalline poly(L-lactide)-block-poly(vinylidene fluoride)-block-poly(L-lactide) (PLLA-b-PVDF-b-PLLA) triblock copolymers were successfully synthesized through ring opening polymerization of L-lactide and benzoyl peroxide initiated polymerization of vinylidene fluoride, followed by copper(I)-catalyzed azide-alkyne coupling of the functionalized PLLA and PVDF. Three triblock copolymers with different block ratios were prepared via this synthetic approach. The block copolymers were miscible in the melt, and an alternating crystalline lamellar nanostructure was formed upon crystallization from the homogeneous melt. Crystallization behavior of the PLLA component depends strongly on the block composition. The crystallization temperature of the lower temperature crystallizing PLLA block increased considerably with respect to its parent homopolymer for rather symmetric block copolymers, indicating a strong nucleation effect, while on the other hand asymmetric block copolymers with low PLLA content demonstrated a large decrease of crystallization temperature, due to a fractionated crystallization process. A confined crystallization mechanism for the PLLA blocks was suggested, indicated by the low degree of crystallization compared to the respective homopolymers, and confirmed by microstructure analysis performed during isothermal crystallization. Contrary to PLLA, crystallization of the higher temperature crystallizing PVDF component within the block copolymer was not influenced by the block composition and similar crystallization behavior was observed with respect to PVDF homopolymers.

The equilibrium conformations of isolated comb copolymer ring molecules in an athermal solution are investigated by off-lattice Monte Carlo simulations. The molecules considered consist of a closed flexible backbone densely grafted with flexible or rigid side chains. The study focuses on the influence of the length of the side chains on the conformational behavior. As a function of the side chain length the structure gradually stiffens until the size of the side chains approaches the diameter of the ring. Longer side chains do not influence the backbone conformation any further. The results are compared with the large body of knowledge available for linear cylindrical comb copolymer brushes.

The off-lattice Monte Carlo method is applied to investigate the equilibrium conformations of isolated comb copolymer cylindrical brushes in an athermal solution. The molecules considered consist of a flexible backbone, which is densely grafted with semiflexible side chains. The study focuses on the influence of the degree of intrinsic stiffness, λside, of the side chains on the conformational behavior of the molecules. It is demonstrated that with a fixed side chain length, M, the local length scale conformational fluctuations of the backbone increase as a function of λside. However, the persistence length, λ, of the cylindrical brush increases considerably with the side chain stiffness, indicating that the backbone becomes more extended at the large length scale. Moreover, as a function of λside, there is an increase in the ratio λ/D of the persistence length and the diameter, D, of the brush. This behavior is in good agreement with recent theoretical predictions and provides important new insight in the latest experimental observations.

The effect of intramolecular excluded volume interactions on the conformations of isolated comb-shaped copolymers—‘‘molecular bottle brushes’’—in athermal solvents confined between two hard impenetrable parallel plates is studied by off-lattice Monte Carlo simulations. Equilibrium conformational properties of molecules consisting of a freely jointed backbone of 100 hard spheres (beads), where 50 equally flexible side chains of lengths M up to 30 beads are connected, are determined as a function of the width of the slit, including the pure two-dimensional (2D) case. Besides general properties such as the size and the shape of the chains and the orientation of the chains with respect to the confining plates, the persistence length of the bottle-brush backbone λ is considered in particular. It is demonstrated that due to the side chains, the backbone is, in fact, effectively confined between two soft plates, i.e., the side chains act like softening springs between the backbone and plates. The most striking result is that, unlike the three-dimensional (3D) situation, in the 2D case the ratio between λ and the diameter D, λ/D, of the bottle brush starts to increase as a function of the side chain length for M≥10. For 3D, an increase of λ/D (the essential parameter for lyotropic behavior) as a function of M is predicted by theory but has so far not been observed numerically for the regime studied (i.e., M≤30). These results suggest that due to the weaker excluded volume effect in 3D, a possible upturn of λ/D may only be observed for longer side chains than studied so far.

Phase behavior of solvent free mixtures of homopolymers and amphiphiles capable of hydrogen bonding is analyzed in weak segregation limit applying a theoretical model describing the main features of the system as a function of composition, temperature and strength of hydrogen bonding. Phase diagrams obtained contain relatively small regions of stable ordered structures, while the regions of macrophase separation representing equilibria between ordered and homogeneous phases are rather broad. The influence of the surfactant (amphiphile) length on the order–disorder transition temperature and the critical wave vector is studied. The phenomenon of reappearing homogeneous phase is considered. The predictions of the present theory for experimental systems are thoroughly discussed on the basis of a comparison with the extensively investigated poly(4-vinyl pyridine)–amphiphile systems taking into account the limitations of the model applied.

A three dimensional continuous space Monte Carlo computer simulation study is presented to discuss the extension of flexible, linear polymer chains due to the presence of equally flexible side chains. We consider the enhancement of the persistence length of bottle-brush structures in an athermal solution due to steric interactions between the side chains, The largest structure studied consists of a backbone of 100 beads with 50 side chains of 20 beads each, The persistence length lambda is evaluated in two different ways using the radius of gyration of the backbone and the bond angle correlation function, respectively. A correct description of the backbone conformations is shown to require at least two characteristic lengths. At a small length scale the backbone behaves flexible; the extension occurs at a larger length scale. There is a strong indication that the ratio between the persistence length and the diameter, which is the determining factor for lyotropic behavior of conventional semiflexible chains, levels off as a function of the side chain length. The value of this ratio is, moreover, too small to induce lyotropic behavior along this line. Recent experimental observations of lyotropic behavior of polymacromonomers are discussed in terms of these findings. (C) 1997 American Institute of Physics.

The phase behavior of block copolymer based supramolecular complexes polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) and amphiphilic pentadecylphenol (PDP) molecules resembles the phase behavior of conventional block copolymers. Several PS-b-P4VP(PDP) complexes are found to self-assemble into gyroid nanostructures. Typically, the grains are randomly oriented with a maximal size of several micrometers. Here, the orientation of a gyroid PS-b-P4VP(PDP) complex upon shearing is reported. It is found that the (111) gyroid lattice direction orients parallel to the shear direction after only several seconds of large amplitude oscillatory shearing. Oriented gyroid complexes can be used as templates for the preparation of metal nanofoams with improved ordering with potentially superior properties.

Hierarchical self-assembly of supramolecular double-comb diblock copolymer complexes, based on a diblock copolymer in which both blocks can participate in the hydrogen bonding with short amphiphiles, is discussed. A symmetric poly(4-vinylpyridine)-b-poly(N,N-dimethylacrylamide) (P4VP-b-PDMA) diblock copolymer was synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization. Supramolecular double-comb complexes were prepared by hydrogen bonding of 3-pentadecylphenol (PDP) to both blocks, as confirmed by infrared spectroscopy. The self-assembled structures were studied using small-angle X-ray scattering (SAXS), wide-angle X-ray scattering, and transmission electron microscopy (TEM). Self-assembly of the supramolecular complex containing a stoichiometric amount of PDP resulted in a lamellar-in-lamellar structure in which the large length scale is formed by the phase separation between the supramolecular blocks of the supramolecular complex. Both domains contain a smaller lamellar mo...

PVDF-based block copolymers have been employed as precursors for the construction of PVDF/PMAA/Ni nanocomposites. New poly(tert-butyl methacrylate)-block-poly(vinylidene fluoride)-block-poly(tert-butyl methacrylate) (PtBMA-b-PVDF-b-PtBMA) triblock copolymers were synthesized via atom transfer radical polymerization (ATRP) of tBMA from chlorine-terminated PVDF macroinitiators. The alternating crystalline-amorphous lamellar nanostructure and the spherulitic microstructure indicate the dominant role of crystallization of the PVDF segments during structure formation. The polar beta-crystalline phase of PVDF has been detected within the block copolymer films. Hydrolysis of the tBMA segments and subsequent backfilling of the remaining polymer template with nickel through electroless metal deposition generated PVDF/PMAA/Ni nanocomposites. The beta-polymorph was preserved during hydrolysis and electroless plating, as well as the lamellar morphology.

Supramolecular complexes of polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP) diblock copolymers and small molecules such as pentadecylphenol (PDP) have been studied extensively in recent years. In the present study, PS-b-P4VP(PDP) complexes with a minority P4VP(PDP) block are morphologically characterized focusing on the region between the lamellar and cylindrical phase. Dynamic mechanical measurements and small-angle X-ray scattering are used to follow the transitions between the ordered states upon heating/cooling. The self-assembled state at various temperatures is determined by small-angle X-ray scattering and transmission electron microscopy. In contrast to the opposite case of majority P4VP(PDP) blocks, where the transition from lamellar to cylindrical structures frequently occurs via the gyroid morphology, the complexes adopt the hexagonally perforated layered morphology in a broad range of compositions. Although known as a metastable phase in pure diblock copolymers, the hexagonally perforated layered phase appears as an equilibrium phase in PS-b-P4VP(PDP) complexes, being stabilized by the presence of the hydrogen-bonded PDP side chains in the minority component domains.