Copolymerization free radical

The copolymerization of a vinyl monomer and a divinyl monomer is fi-equently used to prepare a gel. In this section, the basics required to treat a tree radical copolymerization trom the theoretical point of view will be discussed. 

Each of these propagation steps can proceed at different rates, so we need four rate constants to describe the kinetics of the propagation step. We will use a double subscript where the first number refers to the monomer at the terminal position of the chain radical while the second number refers to the type of monomer that is being added. The rate constant k v for example, refers to the rate of adding a monomer of type 1 to a growing chain whose terminal group also happens to be a monomer of type 1. The rate constant k2i would describe the rate of adding a 1 to an end of type 2. And so on. 

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Styrene-butadiene rubber is prepared from the free-radical copolymerization of one part by weight of styrene and three parts by weight of 1,3-butadiene. The butadiene is incorporated by both 1,4-addition (80%) and 1,2-addition (20%). The configuration around the double bond of the 1,4-adduct is about 80% trans. The product is a random copolymer with these general features ... 

In some instances, the resist polymer can be prepared in a single step by direct polymerization of the protected monomer(s) (37,88), entirely avoiding the intermediate PHOST. HOST-containing resist polymers have also been prepared by free-radical copolymerization of a latent HOST and a stable, acid-labile monomer, eg, the copolymerization of acetoxystyrene with tert-huty acrylate, followed by selective removal of the acetoxy group (89) (Fig. 30). 

In all manufacturing processes, grafting is achieved by the free-radical copolymerization of styrene and acrylonitrile monomers in the presence of an elastomer. Ungrafted styrene—acrylonitrile copolymer is formed during graft polymerization and/or added afterward. 

Table 5. Free-Radical Copolymerization Reactivity Ratios,...

Free-radical copolymerizations have been performed ia bulb (comonomers without solvent), solution (comonomers with solvent), suspension (comonomer droplets suspended ia water), and emulsion (comonomer emulsified ia water). On the other hand, most ionic and coordination copolymerizations have been carried out either ia bulb or solution, because water acts as a poison for many ionic and coordination catalysts. Similarly, few condensation copolymerizations iavolve emulsion or suspension processes. The foUowiag reactions exemplify the various copolymerization mechanisms. 

Free-Radical Gopolymerization. Examples of the types of copolymers formed by free-radical copolymerizations are shown ia equations 18—20, where S = styrene [100-42-5] B = butadiene [106-99-0] and AIBN = azobisisobutyronitrile [78-67-1] (see Initiators) (27—29). 

Poly(MA-CDA) was synthesized by a free radical copolymerization of maleic anhydride and 7,12-diox-aspiro-[5,6]-dodec-9-ene, followed by hydrolysis in... 

Poly(MA-CDA) was synthesized as described previously by a free radical copolymerization followed by hydrolysis in aqueous solution. By the fractional precipita- n of the copolymerization product (MW = 14,200, MW/Mn = 3.1) different average-molecular weight po-ly(M A-CDA)s with narrow polydispersity were obtained as shown in Table 2. 

Fig. 1. Comparison of experimental and theoretical values of Mc at free-radical copolymerization of AAm with MBAA as a crosslinking agent CT — total concentration of monomers, C — that of MBAA C = 10 wt% (/), CT = 6.7 g dl-1 (2). From Baselga et al. [18]...

To determine the crosslinking density from the equilibrium elastic modulus, Eq. (3.5) or some of its modifications are used. For example, this analysis has been performed for the PA Am-based hydrogels, both neutral [18] and polyelectrolyte [19,22,42,120,121]. For gels obtained by free-radical copolymerization, the network densities determined experimentally have been correlated with values calculated from the initial concentration of crosslinker. Figure 1 shows that the experimental molecular weight between crosslinks considerably exceeds the expected value in a wide range of monomer and crosslinker concentrations. These results as well as other data [19, 22, 42] point to various imperfections of the PAAm network structure. 

In which the ratio m/n is close to 3. The silane was produced by free radical copolymerization of vinyltriethoxysilane with N-vinylpyrrolidone. Its number-average molecular weight evaluated by vapour-phase osmometry was 3500. Porous silica microballs with a mean pore diameter of 225 A, a specific surface area (Ssp) of 130 m2/g and a pore volume of 0.8 cm3/g were modified by the silane dissolved in dry toluene. After washings and drying, 0.55% by weight of nitrogen and 4.65% of carbon remained on the microballs. Chromatographic tests carried out with a series of proteins have proved the size-exclusion mechanism of their separation. 

Several wide-porous affinity and size-exclusion chromatographic supports were prepared by Ivanov, Zubov et al. by means of acylation of aminopropyl-glass supports by copolymers of N-vinyl pyrrolidone (N-VP,1) and acryloyl chloride (AC,2), M = 7700 and 35000 respectively [50, 51]. The copolymers prepared by free radical copolymerization contain their units almost in equimolar proportion, with high tendency to alternation expected from the copolymerization parameters (rj = 0.035, r2 = 0.15 [52]). Residual carbonyl chloride groups of the chemisorbed copolymer could be transformed to 2-hydroxyethylamides which were solely... 

Kuchanov, S. Modern Aspects of Quantitative Theory of Free-Radical Copolymerization. Vol. 103, pp. 1-102. 

Formaldehyde-to-phenol ratios, 404 V-Formyl amines, 158 Fourier transform infrared (FTIR) spectrometry, 116, 300, 387, 407-408 Fradet, Alain, 17 Free-radical copolymerization, 59 Friedel-Crafts acrylation polymerization, 332-334... 

Siloxane Containing Graft and Segmented Copolymers by Free-Radical Copolymerization... 

The synthesis of PDMS macromonomers with vinyl silane end-groups and their free-radical copolymerization with vinyl acetate, leading to poly(vinyl acetate)-PDMS graft copolymers, was described 346). The copolymers produced were later hydrolyzed to obtain poly(vinyl alcohol)-PDMS graft copolymers. 

Free-radical copolymerization of vinyl acetate with various vinyl siloxane monomers was described 345). Reactions were conducted in benzene at 60 °C using AIBN as the initiator. Reactivity ratios were determined. Selective hydrolysis of the vinyl acetate units in the copolymer backbone was achieved using an aqueous sodium hy-droxide/THF mixture. The siloxane content and degree of hydrolysis were determined by H-NMR. 

The chief application of macromonomers is, however, to provide easy access to graft copolymers 69,70,71,84,851 by free radical copolymerization with a vinylic or acrylic comonomer. This grafting through process offers graft length control and provides randomness of graft distribution. 

The electrophilic functions most commonly used in grafting onto processes are ester 141 144), benzylic halide 145,146) and oxirane, 47). Other functions such as nitrile or anhydride could be used as well. The backbone is a homopolymer (such as PMMA) or a copolymer containing both functionalized and unfunctionalized units. Such species can be obtained either by free radical copolymerization (e.g. styrene-acrylonitrile copolymer) or by partial chemical modification of a homopolymer (e.g. 

Graft copolymers can also be made by free radical copolymerization of a macromonomer with an acrylic or vinylic comonomer, as mentionned earlier 69-71>. 

More recently, Tsoukas et al. (1982) studied the impact of various control schemes, including temperature and/or monomer addition and/or initiator as manipulated variables, on the performance of a free-radical copolymerization reactor. They formulated the... 

Emulsion breakers are made from acrylic acid or methacrylic acid copolymerized with hydrophilic monomers [148]. The acid groups of acrylic acid and methacrylic acid are oxalkylated by a mixture of polyglycols and polyglycol ethers to provide free hydroxy groups on the molecule. The copolymers are made by a conventional method, for example, by free radical copolymerization in solution, emulsion, or suspension. The oxalkylation is performed in the presence of an acid catalyst, the acid being neutralized by an amine when the reaction is complete. 

Ra, Ra symbol of a-type radical or ion and its concentration kap constant of propagation reaction between Ra and M klap constant of termination reaction between Ra and R rap> rfia reactivity ratios for binary free-radical copolymerization of monomers Ma and M ... 

An individual approach has been developed which provides a quantitative description of living free-radical copolymerizations which are presently of utmost academic and industrial interest (see, for example, [29-31] and references cited therein). A feature peculiar to these processes is the stepwise growth of a... 

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