Micronetwork

The bracket (1 — 2/f) was introduced into the theory of rubber elasticity by Graessley [23], following an idea of Duiser and Staverman [28]. Graessley discussed the statistical mechanics of random coil networks, which he had divided into an ensemble of micronetworks. 

The IUPAC Commission on Macromolecular Nomenclature recommended micronetwork as a term for microgel [47] and defined it as a highly ramified macromolecule of colloidal dimensions. However, it should be noted that a micronetwork implies a structure and not a macromolecule or a particle, that a high ramification is not typical for these molecular particles and that the same wrong dimension is used as with microgel. 

Covalent polymer networks or (Class II) crosslinked macromolecular architecture polymers rank among the largest molecules known. Their molecular weight is given by the macroscopic size of the object for instance, a car tire made of vulcanized rubber or a crosslinked layer of protective coating can be considered one crosslinked molecule. Such networks are usually called macronetworks. On the other hand, micronetworks have dimensions of several nanometers to several micrometers (e.g. siloxane cages or microgels). 

The Commission on Macromolecular Nomenclature is currently working on the extension of macromolecular nomenclature to branched and cyclic macromolecules, micronetworks and polymer networks, and to assemblies held together by non-covalent bonds or forces, such as polymer blends, interpenetrating networks and polymer complexes. 

TDFRS has been employed for the study of collective and self-diffusion of PS micronetwork spheres (microgels) [63] with crosslink ratios of 1 10,1 20, and 1 50 in toluene from low to high concentrations. 

Core Shell Structures Based on Polyorgano Silicone Micronetworks Prepared in Microemulsion... 

Summary The polycondensation of methyltrimethoxysilane in the presence of the surfactant benzethonium chloride shows the phenomenology of a polycondensation in microemulsion. These polyorganosiloxane micronetworks can be functionalized with azo groups which are capable of grafting reaction with vinylic monomers. The structure of the resulting core shell systems depends on the polarity of the organic solvent. In DMF moleculary dissolved star-like structures were observed. 

Polymerization in microemulsion has developed into a powerful technique for the preparation of strictly spherical micronetworks [1,2]. The final size of the polymerized particles is solely governed by the ratio of surfactant to monomer concentration, i.e., the fleet ratio S. To predict the final particle size at full conversion, two simple models for the polymerization in microemulsion have been proposed which differ only in some minor details. One of the models considers variable headgroup contributions to the particle radius [3]. This calculation finally arrives at Eq. 1. 

Table 1. Characterization of the polyorganosilicone micronetworks [a] particle molar mass including surfactant...

Precrosslinked" or "intramolecularly crosslinked" particles are micronetworks [1]. They represent structures intermediate between branched and macroscopically crosslinked systems. Their overall dimensions are still comparable with those of high molecular weight linear polymers, the internal structure of micronetworks (p-gels), however, resembles a typical network [2]. Synthesis is performed either in dilute solution or in a restricted reaction volume, e.g., in the micelles of an emulsion. Particle size and particle size distribution can be controlled by reaction conditions. Functional groups can be... 

A new class of liquid crystal/polymer network composite with very small amounts of polymer network (3 Wt%) is described. These composites are formed by photopolymerization of the monomers in-situ from a solution of monomer dissolved in low-molar-mass liquid crystals. Several techniques have proven useful to characterize these polymer networks. This review describes polymer network structure and its influence on electro-optic behavior of liquid crystals. Structural formation in these composites begins with the phase separation of polymer micronetworks, which aggregate initially by reaction-limited, and then by diffusion-limited modes. The morphology can be manipulated advantageously by controlling the crossover condition between such modes, the order of the monomer solution prior to photopolymerization, and the molecular structure of monomers or comonomers. 

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