Solvent extraction Terms Links

Effect of Trapped Cyclics in Networks, if cyclic molecules are present during the end linking of chains, some of them will be trapped because of having been threaded by the linear chains prior to the latter being chemically bonded into the network structure (5,102). The fraction trapped is readily estimated from solvent extraction studies. Some typical results, in terms of the fraction trapped as a function of degree of polymerization of the cyclic (103), showed that, as expected, very small cyclics do not get trapped at all, but almost all of the largest cyclics do. 

Dual-phase continuity, which is defined as the continuity of both polymer I and polymer II domains throughout the macroscopic sample, seems to be better described in terms of spinodal decomposition. In [170] an example of dual-phase continuity was given. PnBA/PS sequential IPNs of various compositions were prepared by UV photopolymerization. PnBA served as network I and PS as network II. Acrylic anhydride (AA) and DVB were used as labile and permanent cross-linkers. After IPN formation, the AA-containing network I was de-cross-linked and solvent extracted. Scanning electron microscopy (SEM) of network II revealed a porous but continuous structure formed by aggregates of fused spherical PS domains. It was shown that network I was continuous, since it could be quantitatively and easily extracted. The major conclusion from this paper relates to the dual-phase continuity of PnBA/PS in sequential IPNs. 

The applications of IL-based surfactants have not been exclusively associated to their utilization as extraction solvents in extraction and/or preconcentration schemes. In fact, another interesting approach consists of utilizing IL-based surfactants as the modifiers of extraction of sorbents when linked to the solid supports forming hemi-micelles or admicelles. The modified sorbents perform better in the solid-phase extraction (SPE) approaches than the conventional sorbents. Gangula et al. termed this methodology as admicellar or hemimicellar SPE in a review published in 2010, covering mainly applications with conventional surfactants [58]. 

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