Polymer composites freeze-drying method

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. 

While many researchers use bacterial cellulose in its native form to create polymers, and some treat the bacterial cellulose by homogenization or hydrolyzation prior to casting, there is very little in the literature about the dissolution of bacterial cellulose as part of a method to create composites. One method that has used the dissolution of bacterial cellulose is electrospinning. Chen et al. [148] used the ionic liquid 1-allyl-3-methylimidazolium chloride to dissolve freeze-dried bacterial cellulose pieces at 70°C while stirring. DMSO was added to the solution to adjust the viscosity at room... 

Most of the methods used for the microscopic characterization of emulsion polymers in terms of their macromolecular composition, molecular weight and crosslinking require the removal of water. For this reason the investigaHons are performed on the dry polymer film or on freeze-dried samples. The methods employed are the standard techniques of polymer characterizaHon (34-36). 

AIBN monomer (2 % w/w) was used as free radical thermal initiator in 15 mL of THF solutions reaction vials. Under nitrogen atmosphere the polar composition was prepared and injected into the vials, and freeze-thaw cycles were followed to eliminate any trace amount of dissolved oxygen under 60 °C for 72 h. The excess amount of methanol (100 mL) was poured into the reaction mixture, filtered and the product obtained. The product again dissolved in DMF and, methanol was used to re-precipitate the product. The unreacted monomers were removed by extraction technique. At 70 °C under vacuum condition for several days the product was dried until the constant weight achieved. The obtained dried polymers were highly soluble in polar solvents. Gravimetric method was used for the determination of conversions. 

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