Radical copolymerization of monomers

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 ... 

The simplest kinetics model for free-radical copolymerization, known as the terminal model, will be analysed here. The principal assumption is that the reactivity of an active centre depends only upon the terminal monomer unit in which it is located, hence the name of the model. As in the analysis of homopolymerization kinetics, it is further assumed that the amount of moncHn consumed in reactions other than propagation is negligible and that copolymer molecules of high molar mass are formed. Thus for free-radical copolymerization of monomer A with moncHno- B, only two types of active centre need be considered ... 

Li, W. Gao, H. Matyjaszewski, K. Influence of initiation efficiency and polydispersity of primary chains on gelation during atom transfer radical copolymerization of monomer and cross-linker. 

For this reason, copolymers 286 and 287 having a polar polymer structure were prepared by radical copolymerization of monomer 283 with methylmethacrylate or 2-hydroxyethyl methaciylate in presence of AIBN (Scheme 114). Indeed, these polymers seemed to be more compatible with the liquid reaction medium because both yield and enantioselectivity were higher widi the two NMO/acetone/H20 and K3Fe(CN)e/i-Bu0H/H20 systems in the AD of trans methyl cinnamate. 

Free radical copolymerizations of monomer with styrene gave the same isomerized structure for the incorporated monomer units. The copolymer was composed of 68% monomer and 32% styrene. 

Example 6.4 In order to analyze equilibrium radical copolymerization of monomers A and B, we define species which contains m units of A and n units of B. Determine the MWD,... 

Example 6.7 For batch reactors carrying out radical copolymerization of monomers A and B, one can use probabUistic arguments to determine average number of A and B, and per chain. Define relevant probabihties and determine these. 

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. 

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]...

Several radical copolymerizations of vinyl 2-furoate with well-known monomers (50 50) were also studied. Complete inhibition was obtained with vinyl acetate, very strong retardation with styrene, vinyl chloride and acrylonitrile methyl methacrylate homopolymerized without appreciable decrease in rate. It is evident that the degree of retardation that vinyl 2-furoate imposes upon the other monomer depends on the stability of the latter s free radical. With styrene and vinyl chloride the small amounts of fairly low molecular-weight products contained units from vinyl 2-furoate which had entered the chain both through the vinyl bond and through the ring (infrared band at 1640 cm-1). 

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. 

From the above reasoning it may be concluded that the quantitative theory as it stands today gives the opportunity to provide an exhaustive description of the chemical structure of the products of free-radical copolymerization of any number of monomers m. 

Free radical copolymerizations of the alkyl methacrylates were carried out in toluene at 60°C with 0.1 weight percent (based on monomer) AIBN initiator, while the styrenic systems were polymerized in cyclohexane. The solvent choices were primarily based on systems which would be homogeneous but also show low chain transfer constants. Methacrylate polymerizations were carried out at 20 weight percent solids... 

Solvent Effects in the Sn Spectra of Poly(TBTM/MMA). Samples of poly(MMA/TBTM) synthesized by the free-radical copolymerization of the appropriate monomers were solutions in benzene with approximately 33% solids (weight to volume). The particular formulation chosen as representative of the class contained a 1 1 ratio of pendant methyl to tri-n-butyltin groups. In preparing the dry polymer, the benzene was removed in vacuo with nominally 5% by weight residual solvent. 

The relative reactivities (in free-radical copolymerizations) of TBTM and MMA are 0.79 and 1.00 respectively (15). With equal concentrations of monomer, an excess of MMA in the polymer would be expected. In the following discussion A will represent the MAA or TBTM unit and B will represent the MMA unit. For A-centered triads four different arrangements are possible AAA, AAB, BAA, and BAB. Analogous sequences apply to the B-centered triads. For a random compositon, Bernoullian statistics should apply (14). With P (the proportion of TBTM) equal to 0.5, the probabilities of each of the A-centered triads is P 2 or 0.25. The AAB and BAA triads are indistinguishable and appear as a single resonance. 

Our research in this field is mainly carried out on a) synthesis and conversion of oligoorganoepoxystannanes b) free-radical copolymerization of organotin monomers with various vinyl monomers and c) cross-linking of organotin macromolecules and development of protective polymeric coatings with specific properties on their basis. 

Free-radical copolymerization of trimethyl- or tributylvinyltin with styrene or methyl methacrylate results in low ( 10%) yield of copolymer. Moreover, both the reaction rate and viscosity decrease considerably with higher vinyltin content in the starting mixture 49). These findings imply that organotin monomers tend to inhibit free-radical copolymerization. 

Andrianov and Zhdanov have developed a method for the synthesis of polymers containing heterochain and carbon-chain units by free-radical copolymerization of metal-containing polyorganosiloxanes bearing a pendant vinyl group with vinyl monomers. The copolymers thus obtained display increased thermal stability and can be used for the production of laminated plastics, adhesives and other valuable materials 53),... 

According to this scheme the fundamental difference in the mechanism of free-radical copolymerization of MA with TASM and of MA with alkyl acrylates is due to the fact that in the former copolymerization intermolecular coordination is involved. This coordination is similar to the effect of various complexing agents (ZnCl2, SnCft and A1C13) on free-radical homo- and copolymerization of vinyl monomers. This effect seems to favor the appearance of isotactic configurations along the main chain. 

It is likely that the observed coordination interaction between individual segments of the macroradicals and monomer units determines the stereoorientation of free-radical copolymerization of organotin methacrylates with MA. 

To elucidate the reaction mechanism, the kinetics of free-radical copolymerization of the monomers concerned was investigated. 

The obtained value of a indicates the proximity of the rate constant values of the addition of TBSM to the macroradicals MA and of MA to TBSM This can be explained by a similar influence of intermolecular coordination on chain propagation. The values of pt and p2 indicate that in free-radical copolymerization of TBSM with MA both free and complex-bound monomers are involved in chain propagation with a higher contribution of the latter. 

Binary free-radical copolymerizations of organotin derivatives of unsaturated acids (tri-n-butylstannyl methacrylate, bis-triethylstannyl maleate (TESM) and P-phenyl-tri-n-butylstannyl methacrylate (PBSM)) with certain vinyl monomers such as styrene (St) 87) and vinyl chloride (VC) have been studied 24,25,92). 

When studying the free-radical copolymerization of methacrylic and acrylic acids with vinyl monomers, it was established that the addition of catalytic amounts of SnCl and (C6Hs)3SnH has a marked effect on the copolymer composition. It was found that complexes are formed by charge transfer between unsaturated acids and the above tin compounds. It has been suggested that the change in polymer composition is caused by the interaction of the tin compounds with a transition complex resulting in a decrease of the resonance stabilization of the latter 94,). 

Examples considered in this paper deal with binary heteropolymers prepared by the method of chemical modification of homopolymers and by the free-radical copolymerization of a mixture of two monomers, Mi and M2. The products of each of these processes is a mixture of an enormous... 

The synthesis and properties of heat-resistant polyazomethines containing 2,5-disubstituted oxadiazole fragments, being insulators convertible into semiconductors by doping with iodine, have been described. The radical copolymerization of alkenes with the fluorescent co-monomer 2-/-butyl-5-(4 -vinyl-4-biphenylyl)-l,3,4-oxadiazole has resulted in useful macromolecular scintillators. Anionic polymerization of 2-phenyl-l,3,4-oxadiazolin-5-one has produced a nylon-type product <1996CHEC-II(4)268>. 

Radical copolymerization of TFE with hydrocarbon functional monomers has also not been widely used, owing perhaps to the high activity in the reaction with the C—H bond with its high probability of chain transfer to the monomer and the polymer, which is a feature of growing perfluoroalkyl radicals, and to poor chemical stability of the copolymers. 

In stepwise reactions, all functional groups take part in bond formation. Their reactivity can be considered independent of the size and shape of the molecules or substructures they are bound to (Flory principle). If such a dependence exists, it is mainly due to steric hindrance. In chain reactions only activated sites participate in bond formation if propagation is fast relative to initiation, transfer and termination, long multifunctional chains are already formed at the beginning of the reaction and they remain dissolved in the monomer. Free-radical copolymerization of mono- and polyunsaturated monomers can serve as an example. The primary chains can carry a number of pendant C=C double bonds... 

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