Freeze-drying method polymerization

Anionic polymerization and block copolymerization were performed by using the high vacuum technique. Rigorously purified monomer, solvent and initiator sealed in individual ampoules were allowed to react in reactor by crushing break-seals. Produced polymers were purified by repeating reprecipitation and isolated by freeze-drying method. 

Polymer formation from monomeric butadiene lipid vesicles is demonstrated by the decrease of the monomer absorption at 260 nm as well as by GPC of the residue of a freeze dried polymer vesicle dispersion. The latter method was also used for proving the formation of polymeric vesicles from the methacryloyl lipids. 

EAAm was synthesized in our laboratory as described previously [24]. Copolymers of DMAEMA and EAAm were prepared by free radical polymerization as follows 7.8 g of distilled monomers (mixtures of DMAEMA and EAAm) and 0.02 g of AIBN as an initiator were dissolved in 100 mL of a (50/50 by volume) water/ethanol mixture. The feed compositions for poly(DMAEMA-co-EAAm) are shown in Table 2. The ampoule containing the solution was sealed by conventional methods and inunersed in a water bath held at 75°C for 15 h. After polymerization, all polymers were dialyzed against distilled-deionized water at 4°C and freeze-dried. 

Glycopolymers hearing a-gal epitopes were constructed through a well-known polymeric synthetic route. The method utilized epitope 48 in an attempt to copolymerize with maimose monomer precursor 45 and acrylamide in an established ter-polymerization method (Fig. 22) [153]. Polymerization was initiated hy ammonium persulfate and Ar,Ar,Ar, Ar -tetramethylethylenediamine in aqueous solution. The final polymer was obtained as a white fluffy material after separation by Bio-Gel P-2 permeation column and freeze-drying (76% yield). Proton NMR spectroscopy in D2O verihed the incorporation of all three monomers in the final glycopolymer, 49. 

Latex is a colloidal dispersion of polymer in an aqueous solvent. This method is more suitable for those polymers that can be prepared via emulsion polymerization or those that have the ability to form emulsion. It consists of an aqueous dispersion/ stabilization of filler using a surfactant followed by the addition of the dispersed filler into the polymer latex. Nanocomposites can be obtained after freeze-drying the above mixture followed by melt processing. The latex method has several advantages including no requirement for organic solvent, reliability, ease of processing, and improved dispersion of the filler in the viscous polymer matrix [70]. 

Bulk polymerization procedures are known. Suspension polymerization in aqueous media loaded with high concentrations of electrolyte are possible. Work has also been carried out on solid-state polymerizations. However, the most important methods of polymerization are solution processes, particularly using water as the solvent. If the dry polymer is desired, it may be extracted with a suitable solvent, precipitated, or isolated by solvent evaporation. Freeze drying or spray drying have also been used. 

Table 6.6 lists microparticles manufactured through double-emulsion routes by membrane and microfluidic devices. It can be seen that the methods afford the production of a variety of products by means of sequential secondary reactions/processes in the double-emulsion droplets, such as polymerization, gelation, evaporation, freeze-drying, and crystallization. 

The polymerization in method [III] will probably be unsuitable for industrial production due to the heat of polymerization, but it can be used to produce a freeze-thaw stable adhesive with rapid drying and good adhesion to paper, which cannot be obtain by other polymerization methods. However, the water resistance of the latex film is not improved. 

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