Studies of the polymerization of diallyl compounds. XVI. Copolymerizations of diallyl esters of aromatic dicarboxylic acids with methylallyl benzoate

Radical copolymerizations of diallyl phthalate (DAP), diallyl isophthalate (DAI), and diallyl terephthalate (DAT) with methylallyl benzoate (MABz) have been carried out in bulk at 60°C, using benzoyl peroxide as initiator. In the copolymerization of DAP with MABz the residual unsaturation of the copolymer decreased with increasing mole fraction of MABz in the feed. In the case of DAI it was nearly constant, regardless of the molar feed ratio, whereas with DAT it tended to increase with increasing mole fraction of MABz in the feed. These results were interpreted by considering the difference of the mode of cyclization in the case of DAP, DAI, and DAT. The following monomer reactivity ratios γ₁ (of the uncyclized radical), γ_c (of the cyclized radical) and γ₂ (of the MABz radical) were estimated on the basis of the cyclocopolymerization mechanism. DAP: 0,84; 0,61; 1,08; DAI: 0,76; 0,52; 1,06. For the copolymerization of DAT with MABz the apparent monomer reactivity ratios based on the general copolymer composition equation were obtained as γ₁ = 0,79 and γ₂ = 1,06.     

Copolymerization of 1-vinylindol with maleic anhydride

The formation of a charge-transfer complex between 1-vinylindole ( 1a ) and maleic anhydride (MA) was detected by ¹H NMR analysis, and the corresponding K_eq was measured (K_eq=0,251 mol in CDCl₃ at 25°C). It could be shown that this complex can be involved both in the initiation and propagation steps of the 1a -MA copolymerization by carrying out spontaneous copolymerization experiments and studying the influence of the feed composition on the conversion and [η] of the copolymer. The structure of the 1a -MA copolymer, investigated by ¹³C NMR spectroscopy, was found to be complicated due to the formation of indoline rings along the chains by an attack of the propagating MA radical at position 2 in the indole ring. As a consequence an excess of MA, with respect to a 1:1 mole ratio of monomer feed, was usually found in the copolymer. The mechanism of the cyclization reaction was clarified by copolymerizing MA with 2-methyl-1-vinylindole ( 1b ), 3-methyl-1-vinylindole ( 1c ), or 2,3-dimethyl-1-vinylindole ( 1d ). An alternating copolymer with MA (mole ratio 1:1 of monomeric units), without irregularities, was obtained only by employing 1d as a comonomer.     

Cyclopolymerization, 12. Mechanism of free-radical cyclopolymerization of acryloyl- and methacryloylmethylallylamines

Cyclopolymerizability of acryloylmethylallylamine (1b) was investigated and compared with that of methacryloylmethylallylamine (1a) which is known to yield a highly cyclized polymer with a small amount of pendant methacryloyl groups. The structural study of poly (1b) revealed that residual unsaturation consists exclusively of allyl groups and the degree of cyclization is very low. ESR measurements on the 1b polymerization system yielded only the acryloyl radical as propagating radical. Thus, 1b is incorporated into the polymer mainly through its acryloyl group and the rate-determining step in the cyclopolymerization process of 1b is intramolecular cyclization. On the other hand, the ESR spectrum of 1a consists of cyclized and uncyclized radicals. In this case intramolecular cyclization does not proceed much faster than intermolecular propagation of the cyclized radical. ESR further revealed that the polymerization of 1a first involves the allyl group and then intramolecular cyclization occurs. The difference in cyclopolymerizabilities between 1a and 1b may be interpreted on the basis of the hypothesis that the lower the polymerizabilities of the monofunctional counterparts of unconjugated dienes, the higher their cyclopolymerizabilities.     

Free radical polymerization of unconjugated dienes, 16. Temperature dependence of the cyclization ratio of the cyclopolymerization of methacrylic anhydride

The temperature dependence of the cyclization ratio of the free radical cyclopolymerization of methacrylic anhydride in chloroform solutions was investigated. The experimental difference between the activation entropy of the intramolecular cyclization and the activation entropy of the intermolecular addition of the growing chain radical onto a monomer molecule was found to agree satisfactorily with the difference calculated on the basis of a semiempirical method. It came out that, even in the present case, the intramolecular cyclizations are favoured over the intermolecular additions by a smaller entropy decrease.     

Kinetic and Copolymer Composition Investigations of the Free Radical Copolymerization of 1‐Octene with Glycidyl Methacrylate

Kinetic and copolymer composition investigations of the free radical copolymerization of 1‐octene with glycidyl methacrylate are reported. The chemical structure of the obtained copolymers is elucidated by ¹H, ¹³C, heteronuclear single quantum coherence nuclear magnetic resonance (NMR) and infrared spectroscopies. ¹H NMR measurements indicate that a maximum statistical incorporation of 1‐octene in the copolymer chain of 32 mol% is obtained when 90 mol% of this comonomer is used in the initial monomer feed of the copolymerization reaction. Furthermore, the reactivity ratios of this comonomer system are estimated using the obtained experimental data, which are fitted to the integral form of the copolymerization equation utilizing a nonlinear least squares approach. To the best of knowledge, this is the first report on the reactivity ratios of this specific comonomer system. To evaluate the potential of the obtained materials as dispersants, the effect of the polymer concentration on the dispersion of copper nanopowders in organic solvents is studied for a copolymer with a 1‐octene composition of 25 mol%.     

Batch and Continuous Thermal Free‐Radical Copolymerization of Styrene with Glycidyl Methacrylate at High Reaction Temperatures

Studies were performed on the free‐radical thermal copolymerization of styrene and glycidyl methacrylate in a batch and a continuous stirred tank reactor. From experiments at low monomer conversions in a batch reactor the monomer reactivity ratios and their temperature dependence were determined between 110, 135, 160°C according to the terminal model. The cumulative copolymer composition could be satisfactorily described as a function of monomer conversion with the equation of Meyer–Lowry. The values of the reactivity ratios could be successfully extrapolated to higher monomer conversions and higher reaction temperatures. The steady‐state behavior of a continuous stirred tank reactor could be very well simulated with respect to the copolymer composition and to the residual monomer ratio up to a reaction temperature of 190°C. At higher reaction temperatures the differences between theory and experimental results increased, perhaps due to the start of thermal decomposition of the copolymers.     

Free radical polymerization of unconjugated dienes. IX. Kinetic evidence of formation of five and six membered rings in the free radical polymerization of divinylether

Some kinetic relationships between the monomer concentration and the composition of the polymers from 1.4-dienes, in terms of monomeric and structural units, are derived taking into account all the cyclization reactions which can occur in the course of the chain growth. These relationships are applied to the results of the analytical determination of the residual unsaturations in the products of the free radical polymerization at 70°C of divinylether in benzene solutions. It is shown that the chain growth takes place exclusively by addition of cyclic radicals onto monomer molecules. Evidence is given that both five and six membered rings are formed in the cyclization steps.     

Phase separation in random copolymers from high conversion free radical copolymerization, 1

The phase separation of random copolymers during free radical copolymerization to high conversion was studied. In order to prepare in situ high impact thermoplastics during the copolymerization process, the attention was focussed on systems in which the more reactive comonomers form thermoplastics, whereas the less reactive components form elastomeric homopolymers. The studied systems (A, B) were (AN, EA), (AN, VA), (CHMA, MA) and (S, BA) (AN: acrylonitrile, EA: ethyl acrylate, VA: vinyl acetate, CHMA: cyclohexyl methacrylate, MA: methyl acrylate, S: styrene, BA: butyl acrylate). These copolymers display varying compositional heterogeneity depending on the different radical reactivity ratios and the feed composition used. Curves of instantaneous copolymer composition versus fractional conversion and the distribution functions of chemical composition were calculated for the various systems. In addition, miscibility diagrams of corresponding low conversion copolymers A_xB_1−x and A_yB_1−y, derived from the same monomer pair (A, B) but differing in composition, were recorded at high temperatures. Phase separation was detected by light microscopy and differential scanning calorimetry (DSC) using cast films. The onset of phase separation depending on the actual stage of copolymerization was recorded. The composition of the copolymers at the onset of phase separation was compared with the miscibility of low conversion copolymer blends. A satisfactory prediction of the start of phase separation during copolymerization is presented.     

Cyclopolymerization, 13. Cyclocopolymerizations of maleic anhydride with 1,5-hexadiene and 2,5-dimethyl-1,5-hexadiene

Cyclocopolymerizations of maleic anhydride ( 1 ) with 1,5-hexadiene ( 2a ) and 2,5-dimethyl-1,5-hexadiene ( 2b ) were compared with those of 1 with 1,4-dienes which have been reported to yield highly cyclized polymers following a bimolecular alternating inter-intramolecular mechanism. The mole ratio of monomeric units of 1 to those of the dienes in the copolymers was almost 2:1, though it changed slightly with the monomer composition in the feeds. Although the fundamental aspect of the copolymerization of 1 with 1,5-dienes was found to be similar to that with 1,4-dienes, the structures of the copolymers are different from those obtained with 1,4-dienes in that not only pendant double bonds, but also other unsaturations were detected. The unsaturations were formed by combination of propagating radicals with the allyl radical, which is considered to be formed by hydrogen abstraction from the penultimate hexenyl group. A mechanism is proposed to explain the degree of cyclization and the copolymer composition.     

Copolymerization of maleic anhydride with ethyl cinnamate and with anethole in chloroform

The composition of the copolymers of maleic anhydride (MA) with ethyl cinnamate (EC) and with anethole (ANE) polymerized in chloroform solutions with a radical initiator is reported. A strong alternating tendency is observed in the ANE-MA copolymer but EC is incorporated dominantly into the EC-MA copolymer. Both ANE and EC form 1 : 1 charge-transfer complexes with MA with the equilibrium constants determined to be 0,0845 and 0,026 L/mol, respectively. Applicability of the terminal, the penultimate and the complex participation models of the copolymerization mechanism is examined by non-linear least-square minimization technique using the most general forms of the composition equations. The complex participation model is found to be slightly in favor for both EC-MA and ANE-MA copolymerizations in CHCl₃.     

Free radical polymerization of unconjugated dienes III. N-allylacrylamide in methanol

The free radical polymerization of N-allylacrylamide at 60°C. in methanol solution is described. The experimental data show that both, the acrylic and the allylic double bonds of the monomer take part in the intermolecular and intramolecular (cyclization) chain propagation steps. In particular it is shown that the allylic double bond has a greater tendency to participate in cyclization reactions than the acrylic one. These results agree with earlier observations on the free radical polymerization of N-allymethacrylamide in methanol solution at 60°C. The relative reactivities of the acrylic and the allylic double bonds in N-allylacrylamide are close to those expected on the basis of copolymerization data for only acrylic and only allylic monomers.     

Radical terpolymerization of dodecyl vinyl ether,fumaronitrile and β-chloroethyl acrylate

The radical terpolymerization of dodecyl vinyl ether (DVE), fumaronitrile (FN) and β-chloroethyl acrylate (CEA) were studied. The following results were obtained: (1) The composition ratios of a donor type monomer (DVE) and an acceptor type monomer (FN) in the terpolymers are always constant and equal to unity regardless of the monomer feed ratios; (2) An amount of CEA as the third component is incorporated in the terpolymer. These results cannot be applied in the usual theoretical treatment of the terpolymerization. In the application, there were the contradictions in which the monomer reactivity ratios R₁ and R₂ depend upon the monomer feed ratios and the theoretical calculated compositions of terpolymers are not always consistent with the experimental one, especially when the experiments were carried out at extreme monomer feed ratios. Therefore, the terpolymerization containing the alternating copolymerizing monomer pair of VDE and FN was considered to be different from the terpolymerization of the usual vinyl compounds and the interaction between DVE and FN might participate in their polymerization. Besides, copolymerizations of DVE with FN, CEA with DVE and CEA with FN were studied.     

Copolymerization of methyl acrylate with isobutylene in the presence of lewis acids

The copolymerization of methyl acrylate (MA) and isobutylene (IB) in the presence of Lewis acids (EtAlCl₂, Et₂AlCl, Et₃Al, AlCl₃, and ZnCl₂) at low Lewis acid/MA mole ratio was investigated. EtAlCl₂ and Et₂AlCl were found to initiate the spontaneous reaction. An alternating copolymer was produced in this reaction when an excess of IB in the initial monomer feed was used. The copolymerization in the presence of Et₃Al, AlCl₃, and ZnCl₂ did not proceed spontaneously and was initiated by dibenzoyl peroxide (BPO). In this case MA-rich copolymers are formed even in systems containing a large excess of IB in the monomer feed. The addition of BPO to systems containing ethylaluminium chlorides strongly diminishes the tendency towards alternating propagation. It was concluded that the mode of initiation has a significant influence on the copolymer composition. The alternating copolymerization by EtAlCl₂ was studied in detail in order to determine the influence of the catalyst concentration, monomer feed ratio, reaction temperature and time on the monomer conversion, copolymer composition, molecular weight and tacticity.     

Ring-opening-closing alternating copolymerization of 2-methyl-2-oxazoline with N-methyldiacrylamide

This paper describes a new ring-opening-closing alternating copolymerization (ROCAC) of 2-methyl-2-oxazoline (five-membered cyclic imino ether, 1 ) with N-methyldiacrylamide ( 2 ). The reaction of a 1 : 1 monomer feed ratio proceeded without any added catalyst to give an alternating copolymer 3 having two structural units formed by ring-opening and ring-closing (cyclization). The structure of copolymer 3 was determined by ¹H, ¹³C NMR, and IR spectroscopies. The extent of cyclization was at most 65%. The copolymerization was reasonably explained by a mechanism of propagation via zwitterion intermediates.     

Copolymerization of styrene with α-chloromaleic anhydride, 2. Spontaneous copolymerization in 1,4-dioxane

α-Chloromaleic anhydride (CMA) copolymerizes spontaneously with styrene (ST) at a higher rate than maleic anhydride (MA), and α,α′ -dichloromaleic anhydride (DCMA) does not copolymerize, even in the presence of a radical initiator. The results obtained from the copolymerization of ST with CMA in 1,4-dioxane in the absence of a radical initiator are as follows: the copolymerization is strongly accelerated by UV-irradiation; the monomer reactivity ratios of ST and CMA at 60°C are 0,06 and 0,00, respectively; the over-all activation energy of the copolymerization is 77,4 kJ · mol^?1 (18,5 kcal · mol^?1); the maximum rate of copolymerization at a constant total monomer concentration is observed at a mole fraction of ST of 0,4 to 0,5. The rate of copolymerization at equimolar feed composition is of second order with respect to the total monomer concentration. From the results obtained here and shown in the preceding paper, it was inferred that initiating radicals for the spontaneous copolymerization are formed through a charge transfer (CT) complex between the comonomers.     

Long‐chain and short‐chain branches in ethene‐methyl acrylate copolymers studied by quantitative 13C NMR spectroscopy

The frequency of long‐chain branches (LCBs) in ethene (E)‐methyl acrylate (MA) copolymers is investigated for material that was synthesized at 150°C and 2 000 bar at different levels of conversion but constant copolymer composition. The copolymers exhibit significantly more LCBs than found in LDPE synthesized under similar conditions. Moreover, it is found that the LCB frequency increases with conversion. At 0.3 mol‐% conversion 0.3 LCBs and at 4.0 mol‐% conversion 1.1 LCBs per 1 000 C atoms are observed. In addition, the frequency of short‐chain branches (SCBs) in the copolymers is investigated. About 9 mol‐% of the acrylate units are alkylated, which corresponds to numbers given in literature. As sensors, both LCB and SCB indices provide valuable information for simulation calculations to determine rate coefficients for inter‐ and intramolecular transfer reactions.     

High‐Pressure Free‐Radical Copolymerization of Ethene and Methyl methacrylate

Free‐radical copolymerization of ethene (E) and methyl methacrylate (MMA) has been studied between 190 and 290°C at 2 000 bar. The reactions were carried out in a continuously operated device at overall monomer conversions mostly below 1.5%. Monomer feed concentration is obtained from the measured mass fluxes. Copolymer composition is determined via elemental analysis. Reactivity ratios, r_E and r_MMA, are derived from non‐linear least squares fitting to the Mayo‐Lewis equation of the compositions of monomer mixture and copolymer. E. g., at 220°C and 2 000 bar, r_E and r_MMA are found to be 0.056 ± 0.004 and 10.0 ± 1.1, respectively. Copolymerization at around 250°C and above to products containing more than 40 mol‐% MMA units is affected by depropagation. This is shown by fitting monomer mixture vs. copolymer composition data up to different MMA contents. The activation energies of both reactivity ratios, E_A(r_E) and E_A(r_MMA), are compared with the associated differences in activation energies reported by the Hanns Fischer group for the addition reactions in solution of appropriate small radicals to E and to MMA. The data from the two sources are found to be in excellent agreement which suggests that the temperature dependence of a wide variety of reactivity ratio data might be accessible from the extended set of activation energies of radical‐molecule addition reactions studied by Fischer and coworkers. At 220°C, r_E is also measured for 1 500 and 2 500 bar. As has already been seen with the E‐BMA system, the arithmetic mean value of the associated homo‐propagation activation volumes allows for an estimate of the pressure dependence of cross‐propagation rate coefficients which in turn provides information about the variation of reactivity ratios with pressure.     

Emulsion copolymerization of acrylonitrile and butyl acrylate, 2. Effect of a radical scavenger on the rate of copolymerization and the copolymer composition

Random copolymers of acrylonitrile and butyl acrylate, covering two sets of compositions, are synthetized by emulsion copolymerization conducted to both low and high conversions. The copolymer formed at low conversion is enriched with acrylonitrile. Addition of a small amount of hydroquinone, however, suppresses the formation of copolymer enriched with acrylonitrile, i.e., the formation of copolymer more homogeneous in composition is favoured. Moreover, the effect of a radical scavenger on the kinetic parameters of the emulsion copolymerization is analyzed. In the presence of a small amount of hydroquinone the molecular weight of copolymer is somewhat increased when compared with that prepared without hydroquinone. In addition, the rate of copolymerization unexpectedly decreases with increasing emulsifier concentration. It is supposed that the recipe ingredients themselves and their reaction products or/and intermediates participate in termination reactions within the monomer swollen polymer particles and probably within the emulsified monomer droplets. The initiation of the emulsion copolymerization of acrylonitrile and butyl acrylate is a two-step process. The first step starts in the aqueous phase by the primary radicals from the water-soluble initiator and acrylonitrile. The second step occurs in the monomer-swollen emulsifier micelles by water-soluble and -insoluble radicals (primary and macroradicals) and by radicals derived from the recipe ingredients.     

Copolymerization of vinyl chloride and methyl acrylate catalyzed by ethylaluminium compounds

The copolymerization of vinyl chloride (VC) and methyl acrylate (MA) in the presence of ethylaluminium compounds (C₂H₅AlCl₂, (C₂H₅)₂AlCl, and (C₂H₅)₃Al) at low ethylaluminium compound (EAC)/MA mole ratios was investigated. An alternating copolymer was produced in this reaction when an excess of VC in the initial monomer feed was used. The addition of dibenzoyl peroxide (BPO) to the systems containing EAC resulted in an increase of the alternating copolymer yield. In polymerization systems containing EAC resulted in an increase of the alternating copolymer yield. In polymerization systems containing EAC combined with VOCl₃ an enhancement of the alternating copolymer yield and formation of VC-rich copolymers were observed. In the polymerization system with (C₂H₅)₃Al? VOCl₃ a VC-rich copolymer was the main product. It was concluded that VC-rich copolymers are formed in the random radical copolymerization which occurs when most of EAC is complexed by the alternating copolymer chain. The structure of alternating and VC-rich copolymers was studied in detail by means of ¹³C NMR spectroscopy.