Shear-Induced Mesophase Organization of Polyanionic Rigid Rods in Aqueous Solution

Funaki, Takafumi; Kaneko, Tatsuo; Yamaoka, Kanji; Ohsedo, Yutaka; Gong, Jian Ping; Osada, Yoshihito; Shibasaki, Yuzo; Ueda, Mitsuru

doi:10.1021/la0364284

Cited by 25 publications

(48 citation statements)

References 15 publications

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“…PBDT has high molecular weight, negative charge and a semi-rigid structure, similar to natural biopolymers, and aqueous solutions of PBDT show a nematic LC state above a signifi cantly low critical concentration (C LC *) of 2-2.8 wt%. We found that the viscosity of PBDT solutions increases dramatically when the concentrations are above the overlap concentration of 0.2-0.3 wt% due to chain entanglement [67,70].…”

Section: Liquid-crystalline Hydrogelsmentioning

confidence: 87%

“…In recent years, we have focused on the synthesis of LC hydrogels using a semi-rigid polyanion poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT) as a dopant [67][68][69][70][71][72][73][74][75]. PBDT has high molecular weight, negative charge and a semi-rigid structure, similar to natural biopolymers, and aqueous solutions of PBDT show a nematic LC state above a signifi cantly low critical concentration (C LC *) of 2-2.8 wt%.…”

Section: Liquid-crystalline Hydrogelsmentioning

confidence: 99%

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Hydrogels with self-assembling ordered structures and their functions

Gong

2011

NPG Asia Mater

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Biomimetic and bioinspired materials are receiving increasing attention because of their robust functionality and potential applications as artifi cial tissue [1,2]. For natural materials, a high degree of sophistication is achieved through self-organization of the various components into ordered and hierarchical structures following a well-defi ned pattern [2][3][4]. Biological tissue possesses these ordered structures, endowing the living organisms with mechanical toughness and functionality, as exemplifi ed by tissues such as bone and cartilage. Th erefore, eff orts should be made to introduce ordered and hierarchical structure into soft, and also hard, synthetic materials. Among the strategies developed to date, self-assembly is a convenient and powerful method for producing ordered structures [5].Self-assembly, the spontaneous organization of discrete components into organized structures, is widespread in nature, such as in protein folding and hybridization of the DNA double helix [3][4][5][6]. Self-assembled structures usually incorporate additional functionalities. For example, phospholipids form a lipid bilayer arou nd the cell as a barrier to the diffusion of ions and proteins, and tropocollagens self-assemble into fi brils collagens that are closely packed in parallel arrays in the tendon, endowing it with excellent mechanical properties [3]. Inspired by nature, molecular self-assembly that is directed through weak, noncovalent interactions has received tremendous attention for the development of systems with ordered structures and resultant functions [1,2,6,7]. Th ese eff orts have resulted in various functional materials based on self-assembled structures including solutions, elastomers, gels and hard materials [1,2,[7][8][9].Gels as a functional system is an emerging fi eld in themselves, possessing a responsiveness to external stimuli such as stress, light, temperature, pH and ionic strength [10]. Gels with molecular assemblies can be produced in organic solvent (organogels) or aqueous solvent (hydrogels). In this review, we focus primarily on functional hydrogels with self-assembled structures. Functional organogels produced by molecular self-assembly have been covered in several excellent reviews [11][12][13][14].Hydrogels as a functional material have their own advantages over organogels. Th e aqueous medium makes hydrogels an ideal candidate for soft biotissue, mimicking its functions for applications such as scaff olds for cell culturing [15,16]. However, producing structured hydrogels is not easy because the ordered structure formation and water content (which introduces fl uctuation) work in opposite directions. Th e typical kinds of molecules capable of forming self-assembled structures in aqueous media are amphiphile, block-copolymer and liquid-crystalline (LC) molecules. Under certain conditions, the ordered structures formed by molecular self-assembly can be frozen in physically or chemically crosslinked hydrogels with additional functionalities, such as anisotropic optical and mechanica...

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Section: Liquid-crystalline Hydrogelsmentioning

confidence: 87%

Section: Liquid-crystalline Hydrogelsmentioning

confidence: 99%

Hydrogels with self-assembling ordered structures and their functions

Gong

2011

NPG Asia Mater

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“…[14][15][16][17][18][19][20][21] We have developed hydrogels with macroscopic anisotropic structure by dialyzing the PBDT aqueous solution into a calcium chloride solution. [18] The diffusion of Ca 2+ induces molecular orientation and electrostatic complexation of the negative charged PBDT, and thus the formation of anisotropic structure with size of several centimeters in the physical hydrogel.…”

Section: Introductionmentioning

confidence: 99%

Hydrogel with cubic-packed giant concentric domains of semi-rigid polyion complex

Arifuzzaman

Kurokawa

et al. 2011

Soft Matter

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We report a novel giant oriented structure observed in plate hydrogels synthesized by photo-polymerization of cationic monomers with cross-linker in the presence of a semi-rigid polyanion as dopant. The giant structure, formed via self-assembly of the semi-rigid polyion complex, consists of millimeter-scale concentric cylindrical domains in cubic packing that are sandwiched by two homeotropically aligned outer layers. A universal relationship between the diameter of the cylinders D and the thickness of the swollen gel T is observed, as D=0.5T, regardless the change in the concentrations of the polyanion and precursor cationic monomer. This result permits us to induce giant concentric structure into hydorgels with the tunable cylindrical size.

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“…36,49 Without shearing, the POM image of a PBDT solution is completely dark towing to the relatively low C P , 2 wt%oC LC * ( Figure 1a). When a circular shear is applied, however, the image shows strong birefringence ( Figure 1c).…”

Section: Synthesis Of Physical Hydrogels With Centimeter-scale Anisotmentioning

confidence: 99%

“…[36][37][38][39][40][41][42][43][44][45][46] We have developed hydrogels with mesoscopic network-like structures via viscoelastic phase separation and millimeter-scale to centimeter-scale ordered structures based on the self-assembly of the semi-rigid polyion complex. [38][39][40][41][42][43][44][45][46][47] In this focused review, we will briefly introduce macroscopically structured hydrogels that are developed by two different methods.…”

Section: Introductionmentioning

confidence: 99%

Hydrogels with a macroscopic-scale liquid crystal structure by self-assembly of a semi-rigid polyion complex

Kurokawa

Gong

2012

Polym J

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Designing hydrogels with self-assembled or self-organized structures has become an attractive field of research because these hydrogels usually have robust functions and promising applications, such as in artificial tissues and optical sensors. However, the self-organized structures developed in synthetic hydrogels via molecular self-assembly are generally limited to the submicrometer or micrometer level, which is far from the related scale achieved in biological tissues. Therefore, it is desirable to create macroscopically ordered structures in hydrogels; these structures should greatly improve the material's functionalities, such as their optical properties. In this review, we generally introduce our recent studies on the synthesis of hydrogels with macroscopic-scale liquid crystal structures based on the self-assembly of a semi-rigid polyanion, poly(2,2 0 -disulfonyl-4,4 0 -benzidine terephthalamide) (PBDT). Upon electrostatic interaction with multivalent cations or polycations, PBDT molecules form semi-rigid complexes or mesoscopic bundles that further self-assemble into macroscopic organized structures and are frozen by the subsequent gelation process. We have developed physical hydrogels with centimeter-scale anisotropic structures, polycationic hydrogels with millimeter-scale cylindrically symmetric structures and plate gels with cubic-packed concentric domains. This work should contribute to the development of macroscopic self-organized structures in hydrogel materials with specific functions.

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Shear-Induced Mesophase Organization of Polyanionic Rigid Rods in Aqueous Solution

Cited by 25 publications

References 15 publications

Hydrogels with self-assembling ordered structures and their functions

Hydrogels with self-assembling ordered structures and their functions

Hydrogel with cubic-packed giant concentric domains of semi-rigid polyion complex

Hydrogels with a macroscopic-scale liquid crystal structure by self-assembly of a semi-rigid polyion complex

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