Combination hydrogel synthesis

Formation of the structure of co-precipitated adsorbents depends on many factors, among which the pH of precipitation of mixture components is one of the most important factors. It should be noted that porosity of the co-precipitated adsorbents is a function of the pH of initial and final precipitation of hydrogels in the case of hydrogels, the pH of initial and final co-precipitation is different, adsorbents formed have a maximum in the sorption capacity (Vs) - composition curve and, vice versa, when the pH of co-precipitated hydrogels coincides, adsorbents produced have the sorption capacity directly proportional to Vs of the components in mixture. It cannot be excluded that the phenomenon revealed is of a general nature and occurs in natural conditions with the appropriate combination of the pH of the medium and the presence of suitable salts. In the present work universality of the found relationship will be proved by numerous examples. This relationship is extremely useful in the synthesis of complex adsorbents with the predicted structural parameters. From the sorption capacities of individual components it is also possible to calculate the mixture composition corresponding to the maximum sorption capacity of porous materials produced. 

In this connection it should be noted that varying the porous structure of solids by various combinations of components with different pH of the initial and complete precipitation of hydrogels (and these combinations are innumerable and diverse, especially in multicomponent systems), it is possible to carry out purposeful synthesis of porous bodies not only with a prescribed structure but also with prescribed properties. Moreover, it may be possible to predict the presence of a maximum in the Vj -composition curve and the behaviour of the structure of precipitated materials with variations of relative contents of the components from sorption properties of individual components in the mixture designed. 

An advantage of radiochemical induced cross-linking is the possibility to combine polymers with different properties. For that purpose, the polymers were separately dissolved in water. The solutions were mixed and irradiated. (Gottlieb et al. 2005) describes the synthesis of temperature-sensitive hydrogel blends of PVME (as thermo-sensitive polymer) and the radiation-cross-linkable polymer PVP (a polymer that is applied in pharmaceutics). The experiments show that the gelation dose of the blend is between the gelation doses of the two pure polymers. 

Alternatively, each molecule can be attached to the carrier material (e.g., a PEG-based hydrogel or glass surfaces that carry thiol or olefin moieties). Synthesis is then performed via adding, for example, the components of an Ugi-reaction in a spatially defined fashion. The identity (or combination of diversity reagents) for each compound is thereby defined by its position in the microarray. Often, fluorescence is used for detection [165], but other technologies such as surfece plasmon resonance (SPR) have been used as well [166]. 

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