Copolymerization procedure

Table 9 The Dispersion Copolymerization Procedures Used for the Synthesis of Uniform Latex Particles...

Styrene monomer was also copolymerized with a series of functional monomers by using a single-step dispersion copolymerization procedure carried out in ethanol as the dispersion medium by using azobisizobu-tyronitrile and polyvinylpyrollidone as the initiator and the stabilizer, respectively [84]. The comonomers were methyl methacrylate, hydroxyethyl acrylate, metha-crylic acid, acrylamide, allyltrietoxyl silane, vinyl poly-dimethylsiloxane, vinylsilacrown, and dimethylamino-... 

A copolymerization approach of 0-9-[2-(methacryloyloxy)ethylcarbamoyl] cinchonine and cinchonidine with methacryl-modified aminopropylsilica particles was utilized by Lee et al. [71] for the immobilization of the cinchona alkaloid-derived selectors onto silica gel. The CSPs synthesized by this copolymerization procedure exhibited merely a moderate enantiomer separation capability and only toward a few racemates (probably because they were based on less stereodifferentiating cinchonine and cinchonidine). Moreover, the chromatographic efficiencies of these polymer-type CSPs were also disappointing. 

Three different synthetic methods have been developed for the copolymerization of CO with olefins. The copolymerization may be initiated by free radicals, or induced by y-rays in addition, a number of transition metal compounds are effective catalysts. These copolymerization procedures are described below. 

Copolymers containing up to 35 mole% of carboxylated vinyl ether were synthesized by regulating the reaction pressure of tetrafluoroethylene in the copolymerization procedure. 

Copolymerization Procedures. The copolymerization kinetics runs were made using azobis(isobutyronitrile) (AIBN) as the initiator, at [M][I] = 15, a total monomer concentration of 14 wt % in water, at 60 °C under N2. Polymers were isolated by precipitation in acetone. The initial rate of polymerization (Rp) was determined by measuring the initial slope of time vs. conversion plots. Analysis of reactivity ratio data was performed by using the Kelen-Tiidos method (13, 14). 

For reasons not explained, but perhaps due to improved grafting efficiency, an addition lithiation step was included in the copolymerization procedures (see Figure 2.3(b)) [74]. sec-BuLi in the presence of tetramethylethylendiamine (1 1 mol ratio) was used to lithiate the cw-polybutadiene carrier backbone in cyclohexane at room temperature. Formation of car-banion at the allylic positions, not limiting to 1,2-vinyl units, was expected. The carbanions are capable of an alkylation or transmetallation exchange reaction with Ti(OBu)4 to form new Ti-carbon sigma bonds. The Ti(IV) was then allowed to reduce to the active Ti(III) species by another Li-polymeryl species before acet-... 

A short description of the copolymerization procedure is as follows Prior to the copolymerization, the relevant acrylate monomer was mixed with styrene, and the initiator was dissolved in this mixture which was then added to PS latex diluted with water. This medium was stirred at room temperature for 24 h to allow the adsorption of monomers on the PS particles. The adsorbed monomer layer at the outer shelf of the particles were then polymerized for 24 h at 85°C with a stirring speed of 200 rpm. Note that the coating procedure did not change the size and monodispersity of the original PS particles. The existance of the functional groups on the PS particle surfaces were confirmed by ESCA, FTIR and electrophoretic mobility measurements (55). 

Hritcu et al. [149] synthesized first cationic PS latexes covered with a shell-containing poly(styrene-co-2-hydroxyethyl acrylate) by a seed copolymerization procedure using an azo initiator. In the second step, grafted chains anchored to the surface were produced by polymerization of fV-(2-methoxyethyl) acrylamide (MEA), in the presence of Ce(lV) as a redox initiator. However, the percentage of MEA found covalently attached to the surface was very low because bulk MEA polymerization forming soluble polymers occurred to a much greater extent than the actual grafting reaction on the particles. 

For spectroscopic characterization these copolymers can be labeled with fluorescent probe molecules, such as pyrene and naphthalene. This can be easily achieved by terpolymerization of AMPS, a hydrophobic methacrylamide, and a small amount of A -(l-pyrenylmethyl)methacrylamide (PyMAm) [24] or A -(2-naphthylmethyl)methacrylamide (2-NpMAm) [22], respectively. The terpolymerizations and their purification can be performed in a manner analogous with the copolymerization procedures described earlier. The fluorescent label content in the terpolymers can be determined by UV-visible absorption spectroscopy. 

Abz-(Cd)MAm] (Scheme 5) [56]. The terpolymers of AMPS-LaMAm— Abz-(La)MAm and AMPS-CdMAm-Abz(Cd)MAm are synthesized by free-radical terpolymerization initiated by AIBN in a manner analogous to the copolymerization procedures detailed in the previous section. The Abz moieties are substituted with bulky hydrophobic groups that are the same as those in the polymers to ensure that the Abz residues are incorporated into the hydrophobic microdomains formed by the hydrophobes and the motional freedoms of the Abz residues are directly affected by the hydrophobic microenvironments. 

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