Polymerization processes solvent-polymer interactions

In industrial processes it is sometimes advantageous to have a strong solvent-polymer interaction. Thus solution polymerization is often performed for applications in which the solvent remains present (e.g., in protective coatings, adhesives, and viscosity modifiers). 

Intercalation of polymers in layered hosts, such as layered silicate and graphene nanoplatelets, has proven to be a successful method to prepare PLS nanocomposites the preparation methods are divided into three main groups according to the processing techniques and starting materials, which include solvent interaction process, in situ polymerization process, and melt interaction method (Sinha Ray and Okamoto 2003). 

Template or matrix polymerization can be defined as a method of polymer synthesis in which specific interactions between preformed macromolecule (template) and a growing chain are utilized. These interactions affect structure of the polymerization product (daughter polymer) and the kinetics of the process. The term template polymerization usually refers to one phase systems in which monomer, template, and the reaction product are soluble in the same solvent. 

In addition to the physical state of reactants, it should be remembered that the ideal behavior is encountered only in the gaseous state. As the polymerization processes involve liquid (solution or bulk) and/or solid (condensed or crystalline) states, the interactions between monomer and monomer, monomer and solvent, or monomer and polymer may introduce sometimes significant deviations from the equations derived for ideal systems. The quantitative treatment of thermodynamics of nonideal reversible polymerizations is given in Ref. 54. 

Numerous workers50 51 52 53 have studied the effect of the counterion on the electropolymerization process. The high concentration of counterion employed means that it can have a dramatic effect on the polymerization process. The electrolyte will influence the conductivity of the solution, the polymer properties and, hence, the rate of polymerization. The nature of the electrolyte salt employed can also have a marked effect on polymer-solvent interactions. 

Another remarkable feature of responsive polymeric systems is that interactions on the molecular scale (the stimulus of some sort) lead to macroscopically detectable changes that are finally employed for the function (e.g., directed delivery of drugs). As the molecular-scale interactions and macroscopic function are so intimately linked it is noteworthy that rather few studies have dealt with the nanoscopic level of these materials. This may be due to the fact that many conventional methods of physical polymer characterization may simply not be able to resolve the many different, often counteracting interactions [18, 49, 50]. In processes like a response of any kind, solvent-polymer, solvent-solvent, and polymer-polymer interactions all play a cmcial role. Better understanding of the structure and interactions on the nanoscale is not only of value in itself but it may also shed light on similar processes in biomacromolecules and may aid the design and control of responsive polymers with respect to their applications [8, 48, 49]. These applications can be counted to the above-mentioned societal need of health, as responsive polymers are hot candidates for, e.g., drug or nucleic acid delivery purposes. 

The monomers have much better solubility and permeability than polymers. The interaction and homogeneity are expected to be better in the resulted composite. The coexisting inorganic moieties can act as nuclei, thus the formed insoluble polymer chains are deposited on them. In addition, the cross-linked polymers cannot be dissolved in solvent, so their composites should be prepared through this in situ polymerization process. The composites of epoxy, polydimethylsiloxane (PDMS), and polymer gels have been prepared via this method to improve mechanical and electrical properties (Sun et al., 2013b). 

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