Copolymerization of styrene n-butyl methacrylate

Two free radical-initiated polymerizations are used in turn as examples the homopolymerization of methyl methaK rylate and the copolymerization of styrene n-butyl methacrylate. 

To study the bulk copolymerization of styrene n-butyl methacrylate both conventional and unconventional GPC analyses were used. The normally obtained chromatograms, (from dual U.V. detectors) primarily provided area ratios intficative of composition as a function of retention volume. However, even this information was only obtainable after average compositions had been otherwise determined. Furthermore, in general, since the GPC normally separates on the basis of hydrodynamic volume, the polydispersity of aU polymer molecular properties at e h retention time is of serious concern. 

PolylStyrene co-n-Butyl Methacrylate) Fractionation. OC was developed with the particular idea of elucidating the kinetics of the free radical copolymerization of styrene n-butyl methacrylate. Thus, this polymer provided the main focus of the work. 

Polymers and copolymers were laboratory-prepared samples. Samples W4 and W7 of the diblock copolymer AB poly(styrene-fo-tetramethylene oxide) (PS—PT) were synthesized by producing a polystyrene prepolymer whose terminal group was transformed to a macroinitiator for the polymerization of THF. Samples B13 and B16 of the diblock copolymer AB poly[styrene-h-(dimethyl siloxane)] (PS-PDMS) were prepared by sequential anionic polymerization. Samples of statistical copolymers of styrene and n-butyl methacrylate (PSBMA) were produced by radical copolymerization. Details of synthetic and characterization methods have been reported elsewhere (15, 17-19). 

Percy and coworkers [39,40] synthesized colloidal dispersions of polymer-silica nanocomposite particles by homopolymerizing 4-vinylpyridine or copolymerizing 4-vinylpyridine with either methyl methacrylate, styrene, n-butyl acrylate or n-butyl methacrylate in the presence of fine-particle silica sols using a free-radical in aqueous media at 60°C. No surfactants were used and a strong acid-based interaction was assumed to be a prerequisite for nanocomposite formation. The nanocomposite particles had comparatively narrow size distributions with mean particle diameters of 150-250 nm and silica contents between 8 and 54 wt.%. The colloidal dispersions were stable at solids contents above 20 wt.%. 

Montei and coworkers [240] reported that Nickel complexes [(X,0)NiR(PPh3)] (X = N or P), designed for the polymerization of ethylene, are effective for home- and copolymerization of butyl acrylate, methyl methacrylate, and styrene. Their role as radical initiators was demonstrated from the calculation of the copolymerization reactivity ratios. It was shown that the efficiency of the radical initiation is improved by the addition of PPhs to the nickel complexes as well as by increasing the temperature. The dual role of nickel complex as radical initiators and catalysts was exploited to succeed in the copolymerization of ethylene with butyl acrylate and methyl methacrylate. 

Ueda et al. conducted a systematic study involving the copolymerization of MPC with other vinyl compounds by conventional radical polymerization. Typically, when the MPC was copolymerized in solution with styrene (St) and various alltyl methacrylates such as n-butyl methacrylate (BMA, forming PMB), f-butyl methacrylate (t-BMA), n-hetyl methacrylate (HMA, forming PMH), n-dodecyl methacrylate (DMA, forming PMD), or n-stearyl methacrylate (SMA, forming PMS), the polymerization progressed very well, and a statistically random sequence was obtained. The radical copolymerization of MPC (Ml) and St (M2) in ethanol resulted in the following copolymerization parameters monomer reactivity ratio for Mi and M2 are ri = 0.39, V2 = 0.46, respectively. Also, the Qi and values of the MPC are calculated as Qi = 0.76 and e-i = + 0.51, respectively. In addition, for an MPC (Mi) and MMA (M2) system, the monomer reactive ratio values are ri = 1.61, r2 = 0.66. 

Copolymerization of 4-vinylphenyl isocyanate and styrene at 60°C in toluene in the presence of AIBN affords the expected copolymers (44). Also, 1 1 copolymers from vinyl isocyanate and maleic anhydride are known (54). The copolymeriation of n-butyl isocyanate with a variety of olefins is conducted in toluene/THF at —80°C, using sodium biphenyl as initiator (55). Anionic copolymerization of styrene and hexyl isocyanate affords rod-coil block copolymers. The st5Tene polsrmer forms the coil block, while the polyisocyanate block assumes the rod shape (56). Vinyl-, 9-decenyl-, or y3-allyloxyethyl isocyanate imdergoes copolymerization reactions with styrene or methyl methacrylate (57). 

In contrast, the extension of this promising polymerization process to acrylates proved to be more challenging than expected. Indeed, synthesis of random copolymers of styrene and low amounts of -butyl acrylate provided high yields and narrow molecular mass distributions, but increasing the level of acrylate resulted in higher polydispersities and a lowering of conversion (Table 7). Additionally to random copolymerization, this method was applied for the synthesis of a poly(styrene- )-(styrene-cu-n-butyl methacrylate) block copolymer [265],... 

Figure 2.3 Relationship between polydispersity of the resulting random copolymers and mole percent of styrene in the feed mixture for the copolymerization of (i) styrene and n-butyl acrylate (Ob and (ii) styrene and methyl methacrylate ( ) mediated by 14...

Typically, carboxylate ionomers are prepared by direct copolymerization of acrylic or methacrylic acid with ethylene, styrene or similar comonomers by free radical copolymerization (65). More recently, a number of copolymerizations involving sulfonated monomers have been described. For example, Weiss et al. (66-69) prepared ionomers by a free-radical, emulsion copolymerization of sodium sulfonated styrene with butadiene or styrene. Similarly, Allen et al. (70) copolymerized n-butyl acrylate with salts of sulfonated styrene. The ionomers prepared by this route, however, were reported to be "blocky" with regard to the incorporation of the sulfonated styrene monomer. Salamone et al. (71-76) prepared ionomers based on the copolymerization of a neutral monomer, such as styrene, methyl methacrylate, or n-butyl acrylate, with a cationic-anionic monomer pair, 3-methacrylamidopropyl-trimethylammonium 2-acrylamlde-2-methylpropane sulfonate. 

Consider the copolymerization of 1,3-butadiene with the following monomers n-butyl vinyl ether, methyl methacrylate, methyl acrylate, styrene, vinyl acetate, acrylonitrile, maleic anhydride. If the copolymerizations were carried out using cationic initiation, what would be expected qualitatively for the copolymer compositions List the copolymers in order of their increasing butadiene content. Would copolymers be formed from each of the comonomer pairs Explain what would be observed if one used anionic initiation ... 

Novel sulfonated and carboxylated ionomers having "blocky" structures were synthesized via two completely different methods. Sulfonated ionomers were prepared by a fairly complex emulsion copolymerization of n-butyl acrylate and sulfonated styrene (Na or K salt) using a water soluble initiator system. Carboxylated ionomers were obtained by the hydrolysis of styrene-isobutyl-methacrylate block copolymers which have been produced by carefully controlled living anionic polymerization. Characterization of these materials showed the formation of novel ionomeric structures with dramatic improvements in the modulus-temperature behavior and also, in some cases, the stress-strain properties. However no change was observed in the glass transition temperature (DSC) of the ionomers when compared with their non-ionic counterparts, which is a strong indication of the formation of blocky structures. 

These ultraviolet absorbers (Structure 2) have been homopolymer-ized with AIBN as the initiator and copolymerized with styrene, methyl methacrylate, and to a limited extent with n-butyl acrylate. The amount of incorporation of the functional monomer depended on the type of comonomer. A more extensive study of the copolymerization of methyl 5-vinylsalicylate was carried out with a substantial number of... 

H5P, an a-methylstyrene derivative, seems to have a low ceiling temperature and consequently did not homopolymerize but underwent copolymerization with styrene, methyl methacrylate, and n-butyl acrylate. Based on the homopolymerization attempts, it appears that 2H5P is present as isolated monomer units in these copolymers. The co-polymerization parameters of 2H5V and 2H5P with styrene, methyl methacrylate, and n-butyl acrylate have also been determined. The results are shown in Figure 3 The copolymerization experiments were done to 5 conversions. 

Electron withdrawing substituents in anionic polymerizations enhance electron density at the double bonds or stabilize the carbanions by resonance. Anionic copolymerizations in many respects behave similarly to the cationic ones. For some comonomer pairs steric effects give rise to a tendency to alternate [378]. The reactivities of the monomers in copolymerizations and the compositions of the resultant copolymers are subject to solvent polarity and to the effects of the counterions. The two, just like in cationic polymerizations, cannot be considered independently from each other. This, again, is due to the tightness of the ion pairs and to the amount of solvation. Furthermore, only monomers that possess similar polarity can be copolymerized by anionic mechanism. Thus, for instance, styrene derivatives copolymerize with each other. Styrene, however, is unable to add to a methyl methacrylate anion [379-381], though it copolymerizes with butadiene and isoprene. In copolymerizations initiated by n-butyllithium in toluene and in tetrahydrofuran at —78°C, the following order of reactivity with methyl methacrylate anions was observed [382]. In toluene the order is diphenylmethyl methacrylate > benzyl methacrylate > methyl methacrylate > ethyl methacrylate > a-methylbenzyl methacrylate > isopropyl methacrylate > t-butyl methacrylate > trityl methacrylate > a,a -di-methylbenzyl methacrylate. In tetrahydrofuran the order changes to trityl methacrylate > benzyl methacrylate > methylmethacrylate > diphenylmethyl methacrylate > ethyl methacrylate > a-methylbenzyl methacrylate > isopropyl methacrylate > a,a -dimethylbenzyl methacrylate > t-butyl methacrylate. 

Scheme 24. Examples of antioxidant modified polymers prepared by copolymerization of various monomers with reactive UVAs. (a) Hydroxy benzotriazole-based antioxidants R=H, CH3 (antioxidants with vinyl or isopropenyl reactive groups) R =CeH5, R"=H (styrene), R =COCH3, R"=CH3 (methyl methacrylate) R =COOCH3, R"=H (n-butyl acrylate), (b) Hydroxy benzophenone-based antioxidant copolymerized with ethylene.

In general, bulk polymerization processes have been used to study the copolymerization of A -vinylpyrrolidone with a variety of monomers such as vinyl laurate [31], styrene [32], methyl methacrylate [32], vinyl acetate [32, 33], vinyl chloride [32], crotonaldehyde [34], crotonic acid [35], A -vinylsuccinimide [36], butyl methacrylate [37], N-vinylphthalimide [38], acrylic acid [39], various alkyl acrylates and methacrylates including lauryl methacrylate and stearyl methacrylate [40], and ethylene [41]. Table V lists reactivity ratios of several copolymer systems. 

Subsequently, the oligomeric radicals enter the monomer-swollen polymer particles and continue to polymerize. Examples of ultrasound-induced emulsion polymerization are described for styrene [153, 155, 157], methyl methacrylate [152, 156, 158-161], and n-butyl acrylate [162] and the copolymerization of vinyl acetate and butyl acrylate is also reported [154]. 

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