Spinodal Phase Separation in a Macromolecular Sol → Gel Transition

Feke, Gilbert T.; Prins, W.

doi:10.1021/ma60040a022

Cited by 99 publications

(53 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Agarose was found to be a linear component in agar, and its ideal primary structure was revealed by Araki [1] to be an alternating copolymer of 4-1inked 3,6-anhydro-a-L-galactopyranose and 3-1inked-~-D-galactopyranose residues. Sol-gel transitions of agarose or agar have been studied .from structural points of view, using optical rotation [2][3][4][5] and light scattering measurements [5,6]. The pulsed nuclear magnetic resonance (NMR) method was used in discussing the interaction between agar and water molecules [7].…”

Section: Introductionmentioning

confidence: 99%

Morphology of optically anisotropic agarose hydrogel prepared by directional freezing

Yokoyama

Achife

Momoda

et al. 1990

Colloid & Polymer Sci

View full text Add to dashboard Cite

Agarose hydrogels which showed optical anisotropy were obtained by the directional freezing of starting isotropic gels under a temperature gradient. The directional freezing caused a crystallization of many isolated ice crystal phases, leaving a honeycomb-like gel phase with a higher polymer content. The crystallographic c-axis of the ice crystals was directed to the temperature gradient. X-ray and optical analyses showed that agarose chains had a strong planar orientation along the walls'side surfaces, which were parallel to the equatorial planes of the ice crystals. Scanning electron microscopy showed that the wall consisted of a large number of sheets stacked along the wall thickness; in each sheet, agarose fibrillar structures were found to be densely aligned. With the application of repeated freezing and thawing, the anisotropy of the segregated gel phases increased.

show abstract

Section: Introductionmentioning

confidence: 99%

Morphology of optically anisotropic agarose hydrogel prepared by directional freezing

Yokoyama

Achife

Momoda

et al. 1990

Colloid & Polymer Sci

View full text Add to dashboard Cite

show abstract

“…Molecular structures in the hydrogel, and the corresponding structure of water, have been the object of early studies (see Refs. [14][15][16][17][18][19][20], and other references therein). Mechanisms of gelation and of reversion to s01,16319- 22 factors governing stability of molecular and supramolecular order in the gel structure,23 and possible pathways of biological control of the gel network in U Z V O~~ have also been studied and discussed.…”

Section: Introductionmentioning

confidence: 99%

Sol–sol structural transition of aqueous agarose systems

Biagio¹,

Madonia²,

Newman

et al. 1986

Biopolymers

View full text Add to dashboard Cite

SynopsisA structural transition is reported to occur in aqueous sols of agarose, an electrically uncharged biostructural polysaccharide. The transition has no measurable effect on size dispersity on the shape of the solute polysaccharide as observed by precision photon correlation spectroscopy. It originates a low-angle pattern of scattered light similar to that which monitors phase separations in polymer blends. Thus, it must be due to some extent to spatially modulated polymer clustering, typical of spinodal decomposition. In the interval of temperatures studied, it precedes very distinctly in time the thermoreversible sol-gel transition, which is known to be promoted a t higher concentrations. It also anticipates to an appreciable extent the spatial density modulation observed in the gel. Although reported here for the first time, a spinodal decomposition of the sol that precedes and possibly triggers the processes leading to gelation does not come unexpectedly in terms of site-bond correlated-percolation theory. In general, this occurrence raises the question as t o whether the spontaneous onset of regions of higher and lower polymer concentration (spinodal separation) may be regarded as a novel path for biomolecuiar interactions and the self-assembly of order in biomolecular systems.

show abstract

“…Chosen for this were poorly crystallizable and amorphous polymers such as polyacrylonitrile,l poly(vinyl alcohol),l-3 atactic polystyrene,4 isotactic polystyrene, 5 agar, 6 and gelatin.1.2 Unfortunately, solutions of highly crystalline polymers such as polyolefines have not been studied from this viewpoint, owing to the very fast rate of crystallization and their complicated structures. We could, however, explain the relation between liquid-liquid phase separation and crystallization in a highly crystalline polymer of poly(4-methyl-l-pentene) (P4MlP)jcyclohexane gel, using peculiar morphology and variety of polymorphism of this polymer.…”

mentioning

confidence: 99%

Gelation by Linking of Growing Spherulites in Poly(4-methyl-1-pentene) Cyclohexane Solution

Tanigami

Yamaura

et al. 1986

Polym J

View full text Add to dashboard Cite

ABSTRACT:One of the two types of gelation in a cyclohexane solution of poly(4-methyl-lpentene) is caused by linking of growing spherulites which are nucleated from the one-phase solution. The mechanism is related to that of the spherulitic crystallization by using the Avrami equation. The rate of the crystallization can be estimated by a simple method which takes advantage of the variety of crystal morphology.KEY WORDS Thermo-reversible Gelation I Spherulite 1 Crystalline Particle I Morphology I Crystallization I Avrami Equation I Poly(4-methyl-1-pentene) I Recently, thermo-reversible gelation of polymers from solution was investigated in relation to liquid-liquid phase separation. Chosen for this were poorly crystallizable and amorphous polymers such as polyacrylonitrile,l poly(vinyl alcohol),l-3 atactic polystyrene,4 isotactic polystyrene, 5 agar, 6 and gelatin.1.2 Unfortunately, solutions of highly crystalline polymers such as polyolefines have not been studied from this viewpoint, owing to the very fast rate of crystallization and their complicated structures. We could, however, explain the relation between liquid-liquid phase separation and crystallization in a highly crystalline polymer of poly(4-methyl-l-pentene) (P4MlP)jcyclohexane gel, using peculiar morphology and variety of polymorphism of this polymer. 7 In the gel of P4MlP, two types of gelation mechanisms were found: one gelation is caused by the liquid-liquid phase separation which precedes the crystallization, and another gelation is caused by linking of the growing spherulites or crystalline particles from the one-phase solution. The mechanism of the nucleation and growth observed for the latter crystalline species was considered to be almost identical with that for general solutioncrystallization. There is a critical polymer concentration that distinguishes the gelation from the general solution-crystallization. If the concentration is higher than the critical value, the three-dimensional linking of the crystalline species stops the flow of its system. This is the gelation from one-phase solution of highly crystalline polymers.In this paper, the gelation mechanism by the spherulitic crystallization from the one-phase solution, which was visually observed in the previous work, 7 was more precisely analyzed by using the Avrami equation. 8 31

show abstract

Spinodal Phase Separation in a Macromolecular Sol → Gel Transition

Cited by 99 publications

References 4 publications

Morphology of optically anisotropic agarose hydrogel prepared by directional freezing

Morphology of optically anisotropic agarose hydrogel prepared by directional freezing

Sol–sol structural transition of aqueous agarose systems

Gelation by Linking of Growing Spherulites in Poly(4-methyl-1-pentene) Cyclohexane Solution

Contact Info

Product

Resources

About