Copolymerization of α-Methylstyrene and Styrene

In this paper, the effects of temperature from 60 °C to 80 °C and the molar ratios in monomer feed on the copolymerization of α-methylstyrene(AMS) and styrene(St) were studied. The resulting copolymers, designated as PAS, were characterized by FTIR, GPC, NMR and TGA. When the reaction temperature was below 75 °C, the molecular weights increased almost linearly as the evolution of the copolymerization. The phenomenon revealed that AMS could mediate the conventional free radical polymerization having some features of a controlled system. As the AMS/St = 50/50(molar) in feed, the overall fraction of the AMS unit incorporated into the copolymer was as high as 42 mol%, the monomer conversion could be more than 90 wt% and the molecular weights could reach as high as 4400. However, since the styrene is more reactive than AMS, the AMS fraction in copolymer increased with the overall monomer conversion. The 13C-NMR revealed the products were random copolymers which had triads, such as-AMS-AMS-AMS-,-St-AMS-AMS-(-AMS-AMS-St-) and-St-AMS-St-. TGA curves demonstrated that the degradation temperature of the resulting copolymers went down from about 356.9 °C(0 mol% AMS) to 250.2 °C(42 mol% AMS). This behavior demonstrated that there exist weak bonds in the AMScontaining sequences which could be used as potential free radical generators.     

Cationic Copolymerization with Depropagation. The Copolymerization of α-Methylstyrene and Styrene

ABSTRACT

To evaluate the existence of the depropagation reaction in the copolymerization of vinyl monomers, the cationic copolymerization of α-methylstyrene with styrene was studied. The copolymer composition exhibited an extensive dependency on the temperature of polymerization and the monomer concentration, this fact not being explained by the Mayo-Lewis equation. Treatment of the copolymerization in terms of the depropagation reaction led to an estimate of the monomer reactivity ratio and the equilibrium constant between the polymer and the monomer of α-methylstyrene. A comparison of the equilibrium constants thus obtained with those reported in the literature indicates that the magnitude of the equilibrium constants depends on the sequence length of α-methylstyrene units. By extrapolation to long sequence length, the equilibrium constants approach the values which are reported for high molecular weight poly(α-methylstyrene).     

Thermal Decomposition of Polyisoprene,Poly(p-isopropyl α-Methylstyrene), and Poly(isoprene/p-isopropyl α-Methylstyrene)

Thermal decompositions of polyisoprene, poly(p-isopropyl α-methylstyrene) (PPIPαMS), and poly(isoprene/p-isopropyl α-methylstyrene) (sample M-32) were carried out at various temperatures in the range 200–340° C in a differential thermo-gravimetric apparatus. The undecomposed polymers as well as their decomposed residues were analyzed by gel-permeation chromatography (GPC), infrared spectroscopy (IR), and nuclear magnetic resonance (NMR). Based on the changes observed in the distribution of molecular weights, depolymerization is the predominant step in the decomposition of PPIPAMS and polymer M-32, whereas random scissions predominate in the case of polyisoprene. The combined data of GPC, IR, and NMR indicate that only interchain reactions leading to the formation of cyclized products are present in the decomposition of polyisoprene while interchain as well as intrachain reactions are operative in the case of polymer M-32.     

Donor-Acceptor Complexes in Copolymerization. XLIV. Copolymerization of Styrene and α-Methylstyrene with Acrylic and α-Substituted Acrylic Esters in the Presence of Aluminum Compounds

Abstract

The copolymerization of styrene (S) with methyl acrylate (MA) and with methyl methacrylate (MMA) in the presence of AlEt₃ yields equimolar, alternating copolymers while no polymer is formed in α-methylstyrene (MS)-MA and MS-MMA systems. In the presence of AlEt_1.5Cl_l,5 (EASC), S-MA and S-MMA yield alternating copolymers, S-methyl a-chloroacrylate (MCA), MS-MA and MS-MMA yield a mixture of alternating and cationic polymers, and MS-MCA yields cationic polymer only. In the presence of A1C1₃, S-MA and MS-MA yield a mixture of alternating and cationic polymers and S-MMA and MS-MMA yield cationic polymer only. The cotacticity distributions of the alternating S-MA and S-MMA copolymers prepared in the presence of AlEt₃, EASC, and A1C1, are the same; the coisotactic, co-heterotactic, and cosyndiotactic fractions being approximately in the ratio 1:2:1. The cosyndiotactic fractions of the alter-nating copolymers prepared in the presence of EASC are in the order MS-MMA > MS-MA > S-MCA > S-MMA=S-MA.     

Donor-Acceptor Complexes in Copolymerization. XVI. NMR Analyses of Alternating and Random Copolymers of Styrene and α-Methylstyrene with Acrylonitrile and Methacrylonitrile

An NMR investigation was carried out on random and alternating copolymers of acrylonitrile (AN) with a-methylstyrene (MS) and methacrylonitrile (MAN) with α-methylstyrene and styrene (S). The alternating MS-AN copolymer, prepared by complexation with AlEti_1-5Cl_1-5, was found to have a predominantly coisotactic configuration which was attributed to the interaction between the CH₃ and CN groups. The cotacticity of the alternating copolymer was found to be independent of the temperature of polymerization and the amount of AlEt_1-5Cl_1-5 used for complexation. The NMR spectra of random MS-AN copolymers of varying compositions indicated a high value (0.85) for the coisotacticity probability parameter (σ). The equimolar random MS-AN copolymer was also found to have essentially alternating sequences which was attributed to their low reactivity ratios. The equimolar alternating MS-MAN copolymer was found to have a random stereochemical configuration in which the coisotactic placement was slightly preferrred over the cosyndiotactic placement. The NMR spectrum of the equimolar free radical initiated MS-MAN copolymer lacked the fine structure observed in the spectrum of the alternating copolymer which was attributed to the presence of other sequences. The equimolar alternating S-MAN copolymer was found to have a high coisotactic configuration similar to that observed in the MS-AN copolymer. The equimolar free radical initiated S-MAN copolymer had a random sequence distribution.     

Oligomerization of α-Methylstyrene in the Presence of Mordenite Type Zeolite

The activity and selectivity of coarse-porous H-mordenite in synthesis of cyclic and linear dimers of -methylstyrene were studied.     

Copolymers from α-Pinene. 2. Cationic Copolymerization of Styrene and α-Pinene

A study of the copolymerization of α-pinene and styrene has been carried out at 10°C using anhydrous AlCl₃ as the initiator. It is found that styrene forms copolymer with α-pinene at all mono-meric ratios. A copolymer of 2320–3080 molecular weight is obtained. The softening range of the copolymer is 82 to 85°C. The copolymers are of commercial value.     

Quasiliving Carbocationic Polymerization. II. The Discovery: The α-Methylstyrene System

A detailed analysis of elementary reactions of carbocationic polymerization culminated in the prediction and subsequent experimental demonstration of quasiliving polymerization. Quasiliving polymers are formed in a system provided that the process of chain termination and chain transfer to monomer are absent or reversible, i.e., the propagating ability of the chain end is maintained throughout the experiment, and the molecular weight increases in proportion to the cumulative amount of monomer added. The chain end can be active (carbocation) or dormant (reactivable polymeric olefin or cation source). Chain transfer is suppressed by keeping the monomer concentration low. Quasiliving polymerizations are maintained by continuous slow feeding of dilute monomer to a charge containing the initiating or propagating species (quasiliving polymerization technique). A comprehensive kinetic scheme has been developed that describes quasiliving polymerization in quantitative terms. Quasiliving polymerization was demonstrated experimentally in the “H₂O”/BCl₃/α-methylstyrene and cumyl chloride/BCl₃/α-methylstyrene systems. M _n versus monomer input plots are linear over wide ranges, indicating quasiliving conditions, and poly(α-methylstyrenes) with M _n > 2 × 10⁵ have been obtained, Molecular weight distributions were found progressively to narrow and dispersion ratios M _w/M _n to decrease.     

Anionic Polymerization of α-Methylstyrene. IX. Nature of the Propagating Species

Abstract

The nature of the initiating and propagating species involved in the anionic polymerization of α-methylstyrene has been explored. The earlier hypothesis that multimodal GPC molecular weight distributions in polymers arise solely out of different reaction steps or different ion-pair mechanisms being involved has been modified for poly-α-methylstyrene. Multimodal GPC molecular weight distributions in poly-α-methylstyrene initiated with potassium at 25°C and polymerized at 25°C or higher in THF, p-dioxane, or cyclohexane as solvents have been ascribed to the presence of two different types of tetramers which grow simultaneously but at different rates, each responding to its own well-defined thermodynamic equilibrium and yielding dormant and living polymers. Reaction schemes describing the initiation (at 25°C) and propagation reactions (between -25 and 60°C) in the polymerization (in solution of THF as well as in bulk) of α-methylstyrene initiated with potassium-naphthalene, butyl-lithium, and butyllithium-tetramethylethylenediamine (TMEDA) have been presented. The role of coordinating agents naphthalene and TMEDA in changing irreversible propagations into reversible ones has been emphasized.     

Preliminary Study of Cationic Copolymerization of α-Methylstyrene and Isobutyl Vinyl Ether. II

α-Methylstyrene (α-MS) and isobutyl vinyl ether (IBVE) were copolymerized by using the H₂O/EtAlCl₂ initiator system and CH₂Cl₂ and CH₃Cl solvent in the temperature range from -30 to -90°C. As compared to homopolymerization of α-MS, both yields and molecular weights are reduced upon addition of small amounts of IBVE to the feed. The reactivity ratios were calculated by the method of Kelen and Tödös as well as the Fineman and Ross method, and the combined effect of change of solvent and temperature on reactivity ratios was determined. Effects of feed composition and temperature on the copolymer yield, composition, and number-average molecular weight M _n were studied in detail. M _n showed a novel exponential dependence on the IBVE concentration in the feed. The overall activation energies of molecular weight were determined from the Arrhenius plots for both homo-and copolymerization systems. Based on these and the yield data, a speculation is made regarding reaction mechanism for molecular weight control. NMR and DTA data are reported, which establish the random nature of the copolymers.     

One-Pot Chlorine-Free Synthesis of Chiral Organophosphorus Compounds from Elemental Phosphorus and α-Methylstyrene Dimer

Direct phosphorylation of α-methylstyrene dimer with red phosphorus in KOH/DMSO superbasic system has provided the preparation of 4-methyl-2,4-diphenylpentylphosphonous acid (heating at 105°C for 3 h) or tris(4-methyl-2,4-diphenylpentyl)phosphine oxide (microwave irradiation, 15 min) in 21 and 38% yield, respectively.     

Kinetic Study of Cationic Polymerization of α-Methylstyrene Initiated by BuOTICl3 In Dlchloromethane Solution

The cationic polymerization of α-methylstyrene Initiated by n-BuOTiCl₃ has been studied at -70° C in dlchloromethane solution by using a calorlmetric technique. Polymerizations were performed under high vacuum either in dry conditions for which low monomer conversions were observed (4-12%), or In the presence of added cocatalyst (H₂O or HCl). In these last cases, yields were quantitative, and it was shown that polymerization rate was proportional to added water concentration and first order with respect to catalyst and to monomer. A kinetic scheme is proposed, based on a monomer-Independent initiation step and on a unimolecular termination process. At -70° C, the initiation rate is higher than termination rate during the whole course of the polymerization, and the concentration of active centers increases continuously. The following rate constants were found at -70°C: k_i. = 17 ± 6, k = 2.2 ± 1.1 ± 10⁴,k_trm = 30 ± 15 liter/mole-Sec, and k_t =0 54 ± 0 05 sec^?1. At -50 and -30° C, the concentration of active centers goes through a maximum during the polymerization and incomplete monomer conversions were observed, showing that all the catalyst is consumed. The different rate constants were tentatively estimated at these temperatures by using a simulation method, and this led to a negative value of ca. -7 kcal/mole for the apparent activation energy for propagation, and to a value of ～ 5 kcal/ mole for E_i. The observation of a negative (E_p)_app might be explained either by a shift of the dissociation equilibrium of the growing ends or by a solvation process of these growing ends by monomer prior to the propagation step.     

Tetrazoles: XLVI. Alkylation of 5-Substituted Tetrazoles with Methyl Chloromethyl Ether and α-Methylstyrene

Alkylation of 5-aryl(hetaryl)tetrazoles with methyl chloromethyl ether under conditions of phase-transfer catalysis leads to formation of isomeric 1- and 2-methoxymethyltetrazoles at a ratio of ~1 : 2. The reaction of 5-substituted tetrazoles with -methylstyrene in the presence of trichloroacetic acid gives the corresponding 2-(,-dimethylbenzyl)tetrazoles in high yield and with high regioselectivity.     

Polymerization of α-Methylstyrene with Potassium as Initiator. VII. Thermal Decomposition of the Reaction Products

The polymerization of α-methylstyrene, initiated with high concentrations of potassium in tetrahydrofuran and in p-dioxane or with a butyllithium-tetramethylethylenediamine complex in bulk, was carried out at temperatures above 25°C. The resulting products comprising varying proportions of both low (D + A of [Mbar]w = 2.0 to 4.0 × 10³) and high (B + C of [Mbar]W > 20.0 × 10³) molecular weight components were subjected to 50 min isothermal treatments at different temperatures. The poly-α-methylstyrene samples, prepared under the above mentioned solvent-conditions, which had similar proportions of components D + A and B + C, as characterized by gel permeation chromatography and nuclear magnetic resonance showed that their thermal stability decreased with the following order of solvent-conditions: Bulk > p-dioxane > THF. A comparison of the decomposition results obtained with polymers made up of components D + A and B + C and those made up exclusively of component B + C showed that the percent weight-loss and the decrease in molecular weight associated with the latter component B + C is more pronounced when the low molecular weight component D + A is present.     

Copolymers of α-Methylstyrene with N-Cyclohexylacrylamide: Synthesis,Monomer Reactivity Ratios,and Mean Sequence Length

Abstract

Copolymerization of α-methylstyrene and N-cyclohexylacrylamide was carried out in toluene at 60 ± 1°C using azobisisobutyronitrile as the free-radical initiator. The total concentration of the comonomers was 1.5 mol·L^?1 in the solvent. The copolymers were characterized by ¹H-NMR and ¹³C-NMR spectroscopy, and the copolymer compositions were determined primarily from the ¹H-NMR spectra. The reactivity ratios were found to be r ₁ = 0.08 ± 0.01 and r ₂ = 2.45 ± 0.03 by the Fineman-Ross method, and r ₁ = 0.06 ± 0.01 and r ₂ = 2.43 ± 0.08 by the Kelen-Tüdös method. Mean sequence lengths in the copolymer were estimated from r ₁ and r ₂ values.     

Polymer-Supported Lewis Acid Catalysts. II. Cationic Polymerization of α-Methylstyrene with Polystyrene-Gallium Trichloride Complex as Initiator

The polymerization of α-methylstyrene catalyzed by a polymer-supported Lewis acid catalyst, polystyrene-gallium trichloride complex, is described. The kinetic equation of the cationic polymerization is R_p = k˙C_ms˙C_cat , and the apparent activation energy is 20.9 kJ/mol. The effect of different solvents on the polymerization rate is quite pronounced; for example, the polymerization rate decreased in the following order in the three solvents: CH₂ ClCH₂ Cl < CH₂ Cl₂ < CCl₄. High molecular weight poly(α-methylstyrene) (T_g = 185°C) could be obtained at room temperature. The mechanism of the polymerization is also discussed.     

Synthesis of Sub-100 nm Nanoparticles by Emulsifier-free Emulsion Polymerization of α-Methylstyrene,Methyl Methacrylate and Acrylic Acid

The emulsifier-free emulsion copolymerization of α-methylstyrene (AMS) and methyl methacrylate (MMA) in the presence of functional monomer acrylic acid (AA) was carried out in batch process, giving birth to sub-100 nm nanoparticles. The kinetics of polymerization was investigated. The morphology and size of particles were monitored by TEM. The influences of the functional monomer AA concentration, initiator ammonium persulfate (APS) concentration, and polymerization temperature were studied. It was found that AMS caused a drastic decrease in both the rate of polymerization and the average degree of polymerization. The activation energy calculated from Arrhenius plot turned out to be 83.6 kJ/mol.     

Adhesive Compositions Based on Styrene–Isoprene–Styrene Three-Block Copolymer with Different Modifiers

The adhesive properties of styrene–isoprene–styrene (SIS) three-block copolymer of different brands modified with isoprene oligomer and Regalite R9100 depending on the adhesive composition and the adhesion-contact-formation temperature were studied. It was shown that oligoisoprene acts as a diluent, while Regalite R9100 modifies the system as a whole by decreasing the glass-transition temperature of the microphase of polystyrene blocks and contributes to the increase in the adhesive ability of the composition.     

Quasiliving Carbocationic Polymerization. VII. Block Polymerization of α-Methylstyrene from Quasiliving Poly(isobutyl Vinyl Ether) Dication

Poly(α-methylstyrene-b-isobutyl vinyl ether-b-α-methylstyrene) triblock polymers have been prepared by blocking α-methyl-styrene (αMeSt) from biheaded quasiliving poly(isobuty1 vinyl ether) (PIBVE) cations generated with the bifunctional p-dicumyl chloride/AgSbF₆ initiating system in methylene chloride solvent at -90°C. The products were fractionated with 2-propanol, a good solvent for PIBVE and a nonsolvent for PaMeSt. The 2-propanol-insoluble fractions had much higher molecular weights (M _n = 30,500–69,100) than the starting PIBVE (M _n =6,600–10,600) and contained 13–29 wt% IBVE together with 87–71 wt% αMeSt units. The 2-propanol-soluble fractions (M _n = 7,300–11,600) contained ～90 wt% IBVE and ～10 wt% αMeSt units.     

Polymerization of α-Methylstyrene in Cyclohexane with Potassium as Initiator. IV. Thermodynamic Study and Gel-Permeation Chromatographic Analyses of the Polymers

Polymerization of α-methylstyrene in cyclohexane containing traces of tetrahydrofuran (THF) has been carried out at 40°C with potassium as initiator. The conversion of monomer to polymer was very slow, and a solution with [M]₀ of 5.15 mole/ liter, carrying 0.110 mole/liter of the living ends [LE], required two months to reach a stationary state. The gel-permeation chromatographic (GPC) analyses of these polymers showed them to have multimodal distributions which could be split into components D+A, B, and C similar to those found for poly-α-methylstyrene prepared in THF and α-dioxane as solvents. Furthermore, under identical conditions of [M]₀ and [LE], the GPC distributions of poly-α-methylstyrene prepared in cyclohexane, p-dioxane, and THF were the same, in spite of their different dielectric constants. Under identical conditions of [M]₀ but with different [LE], the effect of excessive [LE] on the GPC distributions of the polymers prepared in cyclohexane was not limited to the component D+A as was the case when THF or p-dioxane were the solvents, but also on the component C which increased its contribution [P]_e to the polymer.