Gelation physical

Ross-Murphy, SB, Physical Gelation of Synthetic and Biological Macromolecules. In Polymer Gels, Fundamentals and Biomedical Applications DeRossi, D Kajiwara, K Osada, Y Yamauchi, A, eds. Plenum Press New York, 1991 21. 

In a first part of this paper, we will discuss results of a 27A1 NMR study of the binding of Al ions on acrylamide-acrylic acid copolymers as a function of pH, at the light of a simple electrostatic model. The second part deals with the phase diagrams, physical gelation and precipitation phenomenon, for different copolymer compositions and under various conditions of concentrations, pH and salinity. 

Beyond the notion of physical networks in which flexible strands are connected by junctions, we will use the term physical gelation in the widest possible sense for polymeric systems which undergo liquid-solid transition due to any... 

Controlled sample preparation is difficult near the gel point where the rate of property change is largest. Physical gelation usually proceeds too rapidly so that the material near the gel point eludes the experiment or the application. However, chemical gelation is most suitable for controlling the evolving network structure. Several approaches have been explored in industrial applications and in research laboratories ... 

As for sol-gel processes, the product of the reactions in chelate processes is small oligomeric species that generate either chemical or physical gelation during film preparation. Although the nature of the species has not been... 

Physical Gelation of a Steroid-Cyclohexane System Kinetic Phenomenol( cal Approach... 

Here, we are concerned with the physical gelation of cyclohexane by low molecular weight molecules 1 and... 

Furthermore the processes of physical gelation may be due to such a phase change across spinodal lines since micro-phase separation may induce the formation of a porous structure which could have high chemo-mechanical response. 

In a similar way, other derivatives of diamines (S,S)-28 and (R,R)-29 were evaluated for their gelation properties. As an example, trans-(R,R) 1,2-bis(dodecy-lureido)cyclohexane and trans-(R,R)-1,2-bis(octadecylureido)cyclohexane can cause physical gelation in a wide variety of organic solvents [76]. As an extension of these studies, novel polymerizable organogelators based on tra s-(7 ,7 )-l,2-bis(ur-eido)cyclohexane derivatives have been reported [77]. In these molecules, the presence of methacrylate-functionalized carboxylic acid groups determines the... 

II. Physical Gelation of Organic Liquids by Low-Mass Molecules 286... 

II. PHYSICAL GELATION OF ORGANIC LIQUIDS BY LOW-MASS MOLECULES... 

Metallomesogens are materials related to liquid crystalline ionic hquids because some of them have ionic structures [68, 69]. Gels based on ionic hquids are also one of related materials. Physical gelation of ionic liquids is accompanied by the... 

P. Terech, Physical Gelation of a Steroid-Cyclohexane System Kinetic Phenomenological Approach, in Reversible Polymeric Gels and Related Systems (ed. P. Russo), American Chemical Society Symposium Series (ACS), 350, 115 (1987). 

They may also be suitable for following gelation in near-line or laboratory experiments at a constant temperature. For example, a vibrational viscometer was used to determine the coagulation time of reimeted milk at fixed temperatures (Sharma et al., 1989, 1992). However, in non-isothermal physical gelation, the elastic modulus depends on the temperature dependence of the resonant response so that precise correction for the influence of temperature must be known. 

Physical gelation occurs as a result of intermolecular association, leading to network formation (see Fig. 5-2). (Physical associations differ from chemical bonds in that the latter are covalent attachments between two atoms and are typically permanent at temperatures... 

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