Structure and Phase Equilibria of Polyelectrolytic Hairy-Rod Supramolecules in the Melt State (original) (raw)
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Phase behavior and structure formation of hairy-rod supramolecules
The European Physical Journal E - Soft Matter, 2003
Phase behavior and microstructure formation of rod and coil molecules, which can associate to form hairy-rod polymeric supramolecules, are addressed theoretically. Association induces considerable compatibility enhancement between the rod and coil molecules and various microscopically ordered structures can appear in the compatibility region. The equilibria between microphase-separated states, the coil-rich isotropic liquid and the rod-rich nematic are discussed in detail. In the regime where hairy-rod supramolecules with a high grafting density appear as a result of the association, three phase diagram types are possible depending on the value of the association energy. In the low grafting density regime only the lamellar microstructure is proven to be stable.
Self-Organization of Hairy-Rod Polymers
Macromolecules, 2003
Self-organized structure formation in the melt of hairy-rod polymers is analyzed theoretically. It is shown that the interplay between unfavorable repulsive rod-coil interactions and stretching of the side chains is responsible for the appearance of three different microphases: one lamellar and two hexagonal. The first-order phase transitions between these are considered in detail. If the side chains are long enough for the elastic stretching free energy to dominate the repulsive interactions, hexagonally ordered domains of hairy-rod cylindrical brushes are formed. The lamellar phase is shown to be stable for shorter side chains and occupies an important part of the phase diagram. In the intermediate side chain length regime another hexagonally ordered structure appears, characterized by cylindrical micelles with an elongated cross section, containing several hairy-rod polymers.
Advanced Materials, 1999
The process of self-organization facilitates formation of ordered polymeric nanoscale structures, [2±7] and hierarchical (tandem) self-organization [8±10] further allows elaboration of responsive materials based on sequences of order-order and order-disorder transitions. Application to rod-like polymers (such as p-conjugated electroactive polymers) could lead to possible new applications, but is not straightforward because such polymers tend to be infusible and poorly soluble. For polymers containing rod-like moieties, self-organization has been achieved based on di-block copolymers with flexible blocks, comb-block copolymers with flexible side chains (so-called ªhairy rodsº), [13±15] and sufficiently dilute mixtures with strong amphiphilic acids. Here we show that one of the simplest p-conjugated electroactive rod-like polymers poly(2,5-pyridine diyl) (PPY), i.e. polypyridine or poly(p-pyridine), stoichiometrically protonated by the simplest sulfonic acid, i.e., methane sulfonic acid (MSA), to form a polymeric salt poly(2,5-pyridine diyl) methane sulfonate, PPY(MSA) 1.0 , forms self-organized nanoscale structures upon complexing with selected alkylphenols, such as octyl gallate (octyl 3,4,5trihydroxybenzoate, OG). In this case, the strength of the hydrogen bonding was sufficient to compensate for the repulsion due to the alkyl tails, which is necessary for self-organization. A supramolecular structure was formed which resembled ªhairy rodº polymers with a fascinating phase behavior. For example, at high temperatures, the mixture consisting of PPY (MSA) 1.0 and OG in the molar ratio 1.0:2.0, formed a homogeneous solution at the resolution of optical microscopes. Cooling below the order-disorder tran-sition (T ODT » 180 C) the mixture became a self-organized complex fluid. At still lower temperatures (T < 110 C), cocrystallization within the polar layers, consisting of protonated PPY-chains, methylsulfonate counter ions, and the aromatic part of OG, was observed. Such supramolecular ªhairy rodº complexes open a straightforward route to prepare processible (fusible) block copolymer-like ordered structures in a number of rod-like polymers.
Materials Research Bulletin, 2002
On the back cover, the book is announced by Dekker as a detailed analysis of the formation and properties of polymer assemblies stabilized by supramolecular interactions. In the``Preface,'' the editor, Alberto Ciferri, de®nes the aim of this book in more detail by placing his emphasis on the description of self-assembled polymers structures that undergo reversible growth by the formation of non-covalent bonds. In addition, as they exhibit interesting novel supramolecular features, a new class of covalently bonded self-assemblies are also included. The book was published in the year 2000 and most chapters contain references up to the year 1999. Therefore, the book was obviously published in a timely fashion and represents the state-of-the-art for the year 2000. The reference lists are comprehensive and provide more than 100 well-selected references for most chapters. The book represents a collection of chapters, written by some of the most prominent leaders in the ®eld. Therefore, each of the chapters is an authoritative account of an important aspect of the ®eld of self-assembly. The ®rst part of the book gives a general introduction to supramolecular interactions and assembly processes. In the second part, linear, planar, and three-dimensional reversible self-assemblies are discussed. Part 3 describes new assemblies stabilized by covalent bonds. Part 4 introduces engineered planar assemblies and ®nally, in Part 5, conclusions and an outlook to future work are presented. The chapters cover the following topics: In Chapter 1, the supramolecular polymerization concept is de®ned and exempli®ed. The underlying forces and effects involved in such systems are described and different growth mechanisms are presented. The second chapter is devoted to the theory of the supramolecular liquid crystal. The analytical and computational approaches are described. The liquid crystallinity in reversibly self-assembling systems makes the connection with the preceding chapter and the third one, which describes the self-assembly of amphiphilic molecules. Selfassembly of monomeric (surfactant molecules) and block copolymer amphiphiles is presented qualitatively. The second part of the book starts with a chapter related to hydrogen-bonded selfassemblies illustrated with several examples. Additionally, both the liquid crystalline and the isotropic phases are exempli®ed. From there, the book progresses to
Diffraction analysis of highly ordered smectic supramolecules of conjugated rodlike polymers
Journal of Applied Crystallography, 2003
A small/wide-angle X-ray scattering and grazing incidence diffraction study of comb-shaped supramolecules of conjugated poly(2,5-pyridinediyl), acid dopant and hydrogen bonded amphiphilic side chains is reported. In solution, polymers are dissolved rodlike particles. When the side-chains are introduced, polymers self-assemble in hierarchic liquid crystals (LC). Diffraction patterns of aligned LC show h00, 020, and 004 reflections, and additional small-angle reflections along the polymer axis. A triangular correlation function indicating a very large correlation length is seen along the smectic axis. An aligned solid structure can be formed by cleaving side chains from the aligned LC.
Self-assembled, aligned, and cleaved supramolecules of poly (2, 5-pyridinediyl)
2002
We report on directed self-assembly in supramolecules containing rod-like polymers. The comb-shaped supramolecules consist of poly(2,5-pyridinediyl), camphorsulfonic acid, and hydrogen bonded amphiphilic side chains. Locally they form highly ordered lamellar structures in which the polymers are stacked. The liquid crystalline state allows facile overall alignment yielding absorption dichroism and polarized photoluminescence. After alignment, cleavage of the amphiphiles results in solid films which retain this optical anisotropy with the high photoluminescence quantum yield. P11.5.1 Mat. Res. Soc. Symp. Proc. Vol. 725 © 2002 Materials Research Society P11.5.5
Reactive and Functional Polymers, 2009
The structures of an amphiphilic conjugated graft copolymer, poly(2,3-diphenyl-5-(trimethylene-heptadeca(oxyethylene)-methoxy-phenylene vinylene) (denoted as PVEO 17) composing of a conjugated DP-PPV backbone and PEO side chains, in bulk and solutions with tetrahydrofuran (THF) and water have been investigated by small-angle X-ray scattering (SAXS). In bulk state, the DP-PPV main chains in PVEO 17 stacked to form flat disk microdomains dispersed in the PEO side-chain matrix. The corresponding wide angle X-ray scattering pattern revealed the existence of crystallinity of the PEO side chains. The structure of the polymer in solution was affected by the solvent quality and the polymer concentration. PVEO 17 chains were relatively well dispersed in THF. In aqueous solutions, however, the amphiphilic PVEO 17 chains aggregated significantly over the concentration range of 1-8 wt%, where the polymer was found to self-organize to form cylindrical micelles with the aggregation number increasing with the increase of concentration. The photophysical properties characterized by UV-Vis and photoluminescence spectroscopy were strongly affected by the aggregation state of the polymer.
Polymer, 2019
The chain conformation of poly(2-vinylpyridine) (P2VP) complexed by 4-((4-((3,4,5tris(dodecyloxy)benzoyl)oxy)phenyl)diazenyl)benzenesulfonic acid at different degrees of neutralization (DN) was addressed by small-and wide-angle neutron scattering technique. To get information on the conformation of P2VP chains spatially confined within lamellar and columnar mesophases at different DNs, the complexes were prepared from a blend of protonated and deuterated P2VP. The 2D scattering patterns of extruded fibers show that at low DN the complex self-organizes in a lamellar phase. The inertial mean distances in the direction parallel and perpendicular to the fiber axis reveal the formation of compact disc-like globules of individual P2VP chains at DN= 25 and 33%. With the increase of DN the interaction between the neighboring side groups along the backbone increases. This results in formation of hexagonal columnar phase at DN=50%, in which the P2VP macromolecules are confined within cylindrical channels forming most probably a disordered helical conformation. At DN=1.0, the enhanced rigidity of the complex hinders the accommodation of the ligands at the interface with polymer chain. This results in appearance of non-bonded side groups in the columns giving rise to a poorly-ordered structure. In contrast to more rigid chains of poly(4-vinylpyridine), the transition from lamellar to columnar mesophase in P2VP occurs at lower DNs, indicating a significant role of the chain flexibility in the formation of ordered structures.
Structural organization of polar-group-containing polymers in the molten state
Colloid & Polymer Science, 1983
Model compounds in which flexible polymethylenic sequences of variable length alternate with -NH2-ZnX 2-groups were characterized both in the crystalline and in the molten state, in order to evaluate the effect of regularly distributed dipoles on the melting behavior of linear flexible chains. Microphase segregation of the polar groups was observed resulting in the formation of smectic meso,hases or of smectic-like fluids. Possible analogies with the structural organization of me' ,en dipole-containing polymers and ionomers are briefly discussed.