Dual-phase transition mechanism

In the 1980s, a dual-phase transition mechanism was proposed, which suggested that both solid- and liquid-phase transition could happen in the same crystallization system. 

3 Structure-directing Effect (SDE) and Templating in the Crystallization Process of Microporous Compounds 

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Thermoresponsive polymeric micelles with PIPAAm block copolymers can be expected to combine passive spatial targeting specificity with a stimuli-responsive targeting mechanism. We have developed LCSTs of PIPAAm chains with preservation of the thermoresponsive properties such as a phase transition rate by copolymerization with hydrophobic or hydrophilic comonomers into PIPAAm main chains. Micellar outer shell chains with the LCSTs adjusted between body temperature and hyperthermic temperature can play a dual role in micelle stabilization at a body temperature due to their hydrophilicity and initiation of drug release by hyperthermia resulting from outer shell structural deformation. Simultaneously, micelle interactions with cells could be enhanced at heated sites due... 

The oscillatory structure just mentioned has been clearly demonstrated to result from quantum-mechanical phase-interference phenomena. The necessary condition264,265 for the occurrence of oscillatory structure in the total cross section is the existence in the internuclear potentials of an inner pseudocrossing, at short internuclear distance, as well as an outer pseudo-crossing, at long internuclear distance. A schematic illustration of this dual-interaction model, proposed by Rosenthal and Foley,264 is shown in Fig. 37. The interaction can be considered to involve three separate phases, as discussed by Tolk and et al. 279 (1) the primary excitation mechanism, in which, as the collision partners approach, a transition is made from the ground UQ state to at least two inelastic channels U, and U2 (the transition occurs at the internuclear separation 7 , the inner pseudocrossing, in Fig. 37), (2) development of a phase difference between the inelastic channels,... 

Since in the A-AiB , ApBq-B and ApBq-AiBn reaction couples the mechanisms of formation of the ArBs layer at its interfaces with adjacent phases are different, in many cases the duplex (dual) structure of this layer, shown schematically in Fig. 4.10, can readily be observed experimentally. The term duplex structure means that in the microstructure of the transition zone between reacting phases the layer of the same chemical compound looks like the layers of two quite different chemical compounds. Its sublayers having a distinct interface may differ by the shape, size or orientation of their grains. 

For the separation of gas mixtures (permanent gases and/or condensable vapors) where the feed and permeate streams are both gas phase, the driving force across the membrane is the partial pressure difference. The membrane is typically a dense film and the transport mechanism is sorption-diffusion. The dual-mode transport model is typically used with polymer materials that are below their glass transition temperature. 

Because of their dual crosslinked nature, both networks exert a unique control over the size, shape, and composition of the phase domains in an IPN. The morphological detail strongly influences, in turn, the physical and mechanical behavior of the material. While Chapter 5 detailed several ways of synthesizing IPNs, little mention was made of how crosslink density, order of polymerization, overall composition, etc. affect the final product. The objective of this chapter will be to explore the interrelationships among synthesis, morphology, and glass transition behavior. Mechanical and engineering properties will be treated in Chapter 7. 

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