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. XVII. NMR Analyses of Random and Alternating Styrene–α-Chloroacrylonitrile Copolymers

The NMR spectra of random and equimolar alternating copolymers of styrene with a-chloroacrylonitrile were studied. The monomer sequence distribution in the random copolymers, prepared in the presence of free radical catalysts, as determined from NMR analyses, was in accordance with the values expected from the r₁ and r₂ values derived from the conventional copolymerization theory. The alternating structure of the copolymer prepared by complexation with AlEt_1-5 Cl_1-5 was confirmed. The equimolar random copolymer, prepared by free radical initiation, was shown to contain essentially alternating sequences.     

SYNTHESIS AND CHARACTERIZATION OF BLOCK POLYMER OF ALTERNATING COPOLYMERS

Block polymer of alternating copolymers, poly[(ST-a-MA)-b(IP-a-MMA)-b-(ST-a-MA)](I), has been synthesized in the presence of AlEt_(1.5)Cl_(1.5),by using Mn_2(CO)_(10)/CBr_4. initiation system.The GPC results indicate that there is no unreacted prepolymer in I purified by precipitation andfractionation. The study of NMR shows that every block of polymer I has alternating structure. The dynamicmechanical properties of I measured by torsional braid method indicate that the polymer has two T_g s,being 38 and 75℃, respectively. The transmission electron micrographs of I show they have two phasestructure and the domain size increases with increasing molecular weight of hard block.     

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.     

Donor-Acceptor Complexes in Copolymerization. VIII. Evidence of Participation of Complexes in Copolymerization of Styrene and Methyl Methacrylate… Al(C2H5))1.5Cl1.5

The copolymerization of styrene and methyl methacrylate in the presence of ethylaluminum sesquichloride in toluene yields alternating copoly-mers, independent of initial monomer ratio. The rate of polymerization is not influenced by the presence of an excess of either monomer, the conversion curves following a parallel course at a given total monomer concentration. When the concentration of the AlEt_1.5Cl_1.5 and the S/MMA ratio are kept constant and the total monomer concentration is increased, the polymerization rate increases and reaches a limiting value at a S/MMA/Al ratio of 2:2:1. A similar result is obtained when the total monomer and the AlEt_1.5Cl_1.5 concentrations are kept constant and the S/MMA ratio is varied. When the concentration of either monomer and the AlEt_1.5Cl_1.5 concentration are kept constant and the concentration of the other monomer is varied, the polymerization rate reaches a limiting value at the same mole ratio, irrespective of which monomer is varied. The rate of polymerization is decreased in the presence of a small amount as well as a large amount of benzoquinone. However, the rate is higher than in the absence of the quinone when the Al/benzoquinone ratio is 2:1. The conductivity of a toluene solution of AlEt_1.5Cl_1.5 increases only slightly upon the addition of methyl methacrylate, a further small increase occurring upon the addition of styrene. The results provide evidence for the participation of a comonomer complex in the polymerization, the optimum composition resulting either from the simultaneous interaction of several equilibria or the alignment of the complexes in the form of a matrix.     

Alternating copolymerization of methyl acrylate with donor monomers having a protected amine group

Attempts were made to copolymerize p-aminostyrene, p-acetamidostyrene, N-methyl-p-aceta-midostyrene, N-(4-vinylphenyl) phthalimide, N-vinyl succinimide, and N-vinyl phthalimide with methyl acrylate complexed with ethyl aluminum sesquichloride. Only reactions involving N-(4-vinylphenyl)phthalimide and N-vinyl phthalimide yielded alternating copolymers. N-vinyl succinimide gave nonalternating copolymers insoluble in common solvents and the other monomers did not copolymerize. In some cases, the conventional radical copolymers were prepared for comparison purposes. The reactivity ratios of the free-radical initiated copolymerization of methyl acrylate (I) with N-(4-vinylphenyl)phthalimide (II) were r₁ = 0.14 and r₂ 1.56. The alternating copolymers were studied by ¹H-NMR and ¹³C-NMR spectroscopy. The alternating copolymer of N-(4-vinylphenyl)phthalimide with methyl acrylate was hydrazinolyzed to form the alternating copolymer of methyl acrylate with p-aminostyrene. Hydrazinolysis of the alternating copolymer of methyl acrylate with N-vinyl phthalimide removed the phthalimide moiety and generated vinyl amine units which readily cyclized with neighboring methyl acrylate units to form copolymers that contained five-membered lactam rings. The infrared (IR) spectra of the hydrazinolyzed products contain bands due to amine or amide groups and are devoid of the characteristic bands of the phthalimide ring.     

Copolymerization of methyl acrylate and vinyl acetate catalyzed by ethylaluminium chlorides

The copolymerization of vinyl acetate with methyl acrylate in the presence of Et₂AlCl, Et_1.5AlCl_1.5, and Et₂AlCl-benzoyl peroxide systems has been investigated. The influence of monomer ratios and organoaluminium compound concentration on the copolymer yield and composition have been determined and discussed. The monomer sequences distribution has been studied by means of ¹³C-NMR. It was found that organoaluminium compounds in the studied systems catalyze not only the alternating copolymerization, but also the homopropagation of both monomers. An alternating copolymer was obtained in reactions carried out at ?78°C, when a large excess of vinyl acetate was used in the monomer feed.     

Polymerization of vinyl chloride by the Ti(O-n-Bu)4–AlEt3–epichlorohydrin catalyst system

The polymerization of vinyl chloride was carried out by using a catalyst system consisting of Ti(O-n-Bu)₄, AlEt₃, and epichlorohydrin. The polymerization rate and the reduced viscosity of polymer were influenced by the polymerization temperature, AlEt₃/Ti(O-n-Bu)₄ molar ratios, and epichlorohydrin/Ti(O-n-Bu)₄ molar ratios. The reduced viscosity of polymer obtained in the virtual absence of n-heptane as solvent was two to three times as high as that of polymer obtained in the presence of n-heptane. The crystallinity of poly(vinyl chloride) thus obtained was similar to that of poly(vinyl chloride) produced by a radical catalyst. It was concluded that the polymerization of vinyl chloride by the present catalyst system obeys a radical mechanism rather than a coordinated anionic mechanism.     

Polymerization of coordinated monomers. XVI. Stereoregulation in the alternating copolymerization of methyl methacrylate with styrene in the presence of metal halides

Triad cotacticities of alternating copolymers of methyl methacrylate with styrene prepared in the presence of zinc chloride, ethylaluminium sesquichloride, and ethylboron dichloride are investigated from the mechanistic point of view by means of ¹H- and ¹³C-NMR. The cotacticities from ¹H-NMR spectra are obtained accurately by using α-d-styrene in the place of styrene and by measuring the spectra on the copolymer in o-dichlorobenzene at 170°C. The relative intensities of three peaks of the splitting signal for the methoxy protons in the nonalternating copolymers obtained by the use of benzoyl peroxide in the absence of metal halides agree well with the cotacticity distribution calculated theoretically by the Lewis-Mayo mechanism with the stereoregulation following Bernoullian statistics. The splitting signals in the ¹H- and ¹³C-NMR spectra of the alternating copolymers prepared in the presence of metal halides cannot be explained by the same mechanism. The relative intensities of three peaks of the splitting signals for the methoxy protons and for the carbonyl carbon in the methyl methacrylate unit (the contents of cotactic triads centered by the methyl methacrylate unit) are not equal to those for the aromatic C₁ carbon in the styrene unit (the contents of cotactic triads centered by styrene unit). The value of f²Y - 4fxfz is not equal to zero, where fx, fy, and fz are the cosyndiotactic, coheterotactic, and coisotactic triad contents, respectively, in the alternating copolymer. Copolymers obtained in the presence of zinc chloride are not exactly equimolar alternating but always contain a methyl methacrylate unit in excess, and the relative intensities of the three peaks for the aromatic C₁ carbon change with the copolymer composition. These results are explained by a proposed mechanism: the alternating copolymerization proceeds through the homopolymerization of a ternary molecular complex composed of a metal halide, methyl methacrylate, and styrene, accompanied with the stereoregulation following first-order Markovian statistics; the increase of methyl methacrylate content in the copolymer prepared in the presence of zinc chloride is caused by the participation of the binary molecular complex composed of a metal halide and methyl methacrylate in addition to the ternary molecular complex.     

Complexation of sequence-ordered methacrylic acid copolymers with poly(4-vinylpyridine)

The complexation of three kinds of sequence-ordered acid (co)polymers with a base homopolymer was studied. The acid polymers used are poly(methacrylic acid) 1 , alternating (1:1) ethylene-methacrylic acid copolymer 2 , and periodic (2:1) ethylene-methacrylic acid copolymer 3 , and the base polymer is poly(4-vinylpyridine) 4. When mixing a methanol solution of 1, 2 , or 3 with that of 4 (0.1 M of each functional group), precipitate was formed immediately for all polymer pairs. All the precipitates contained carboxyl and pyridyl groups in ca. 1:1 molar ratio and showed IR spectra indicating the hydrogen bonding between carboxyl and pyridyl groups. When mixing dilute methanol solutions (10⁻⁴M) of the above polymer pairs, no precipitation was observed, but the extinction coefficient (ϵ_B) at 255 nm of pyridyl groups in 4 was found to increase with an increasing acid polymer concentration. This is ascribed to hydrogen bonding between carboxyl and pyridyl groups in methanol. Based on the ϵ_B variation, the order of complexation constants for acid/base polymer pairs was estimated as follows: 1/4 pair ∼ 2/4 pair ≫ 3/4 pair. © 1996 John Wiley & Sons, Inc.     

Preparation and characterization of alternating copolymer of α-methylstyrene and acrylonitrile made with zinc chloride–peroxide catalysis

The copolymerization of the zinc chloride complex of acrylonitrile in excess acrylonitrile with α-methylstyrene in the presence of lauroyl peroxide is described. Elemental and proton NMR analyses indicate the equimolar nature of the copolymer product. ¹³C NMR examination shows that this copolymer is alternating in structure and suggests that the steric placements of the copolymer are random in nature; that complexation does not lead to a stereoselective enchainment mode is the implication of our results. A copolymer which appears to be similar to our product has been prepared by other workers using Al(C₂H₅)_1.5Cl_1.5 complexation. Our conclusions regarding copolymer stereoregularity differ from theirs.     

Preparation of polymer nanoparticles from renewable biobased furfuryl alcohol and maleic anhydride by stabilizer‐free dispersion polymerization

The spherical polymer nanoparticles of biobased renewable monomers, furfuryl alcohol (FA) and maleic anhydride (MAn), with diameters (D_n) in the range of 120 to 500 nm have been prepared by stabilizer‐free dispersion copolymerization. In acetate or its mixture, the conversion of the monomers greatly depended on the concentration of AIBN. When the molar ratio of AIBN/monomers was 3.6% (wt), the monomer conversion could be as high as 80%. The aggregations of the solvated polymer chains formed the nuclei of the polymer particles. After the nucleation stage, both the monomer conversions and particle sizes increased steadily, while the coefficient of variation of the particle size decreased. The almost linear relationship between the D_n³ and the weight of polymer suggested that there is no significant secondary nucleation. The copolymer of FA and MAn could not dissolve in common organic solvents. Elemental analyses, FTIR and ¹³CP‐MAS spectra showed that the copolymer was close to the alternative copolymer of FA and MAn irrespective to the molar ratios of FA/MAn in monomer feed. Furthermore, the two 2,5‐ and 3,4‐dihydrofuran ring configurations exist in the copolymer and the later is the major one. The reaction of copolymer particles with triethylenetetramine confirmed the reactivity of the succinic anhydride groups at the surface of copolymer particles. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Donor–acceptor complexes in copolymerization. XLIII. Cyclization of alternating and random styrene–(meth)acrylic ester copolymers

Equimolar alternating copolymers of styrene and methyl methacrylate (prepared with Et_1.5AlCl_1.5, SnCl₄, and ZnCl₂) as well as equimolar random copolymer were treated with polyphosphoric acid at 135°C. The extent of cyclization of the alternating copolymers was about 40%, independent of the cotacticity of the copolymer, and there was little or no crosslinking. The random copolymer underwent only 10% cyclization and considerable crosslinking. The extent of cyclization of the alternating copolymer of styrene and methyl acrylate (prepared with Et_1.5AlCl_1.5) was the same as that of the random copolymer and was lower than that of the corresponding methyl methacrylate copolymer. Both alternating and random copolymers underwent extensive crosslinking.     

Reactivity ratios and microstructure determination of vinyl acetate–alkyl acrylate copolymers by NMR spectroscopy

(Vinyl acetate)/(ethyl acrylate) (V/E) and (vinyl acetate)/(butyl acrylate) (V/B) copolymers were prepared by free radical solution polymerization. ¹H-NMR spectra of copolymers were used for calculation of copolymer composition. The copolymer composition data were used for determining reactivity ratios for the copolymerization of vinyl acetate with ethyl acrylate and butyl acrylate by Kelen-Tudos (KT) and nonlinear Error in Variables methods (EVM). The reactivity ratios obtained are r_v = 0.03 ± 0.03, r_E = 4.68 ± 1.70 (KT method); r_v = 0.03 ± 0.01, r_E = 4.60 ± 0.65 (EV method) for (V/E) copolymers and r_v ? 0.03 ± 0.01, r_B ? 6.67 ± 2.17 (KT method); r_v = 0.03 ± 0.01, r_B = 7.43 ± 0.71 (EV method) for (V/B) copolymers. Microstructure was obtained in terms of the distribution of V- and E-centered triads and V- and B-centered triads for (V/E) and (V/B) copolymers respectively. Homonuclear ¹H 2D-COSY NMR spectra were also recorded to ascertain the existence of coupling between protons in (V/E) as well as (V/B) copolymers. © 1995 John Wiley & Sons, Inc.     

Precision synthesis of acrylate multiblock copolymers from consecutive microreactor RAFT polymerizations

Well‐defined acrylate RAFT polymers and multiblock‐copolymers have been synthesized via the use of a continuous‐flow microreactor, in which polymerizations could be executed in 5?20 min reaction time. First, Poly(n‐butyl acrylate) (PnBuA) was synthesized in the micro‐flowreactor by using two different trithiocarbonate RAFT agents. Reaction time and reaction temperature were optimized and collected samples were directly studied with NMR, SEC and ESI‐MS to determine conversion, molar mass and end group fidelity. Using the continuous flow technique, highly reproducible and fast polymerizations yielded quantitatively functionalized PnBuA in a very facile and efficient manner. One batch of RAFT acrylate polymer with a molar mass of 1100 g mol^?1 and excellent end group fidelity was employed as a macro‐RAFT agent for the subsequent copolymerization with different acrylate monomers (2‐ethylhexyl acrylate, t‐butyl acrylate, n‐butyl acrylate). Using this procedure, a sequential multiblock‐copolymer (M_n = 31,200 g mol^?1, PDI = 1.46) consisting of five consecutive acrylate blocks was synthesized. This study clearly demonstrates the potential of using a continuous‐flow microreactor for subsequent RAFT polymerizations towards well‐defined multiblock‐copolymers. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013, 51, 2366–2374     

Reversible Addition–Fragmentation Chain‐Transfer Polymerization of Octadecyl Acrylate

Abstract

Polymerization of octadecyl acrylate (ODA) was carried out in benzene solution using the 2‐cyanoprop‐2‐yl dithiobenzoate (CPDB) as the reversible addition–fragmentation chain‐transfer (RAFT) agent and AIBN as the initiator. The results show the obtained polymer with controlled molecular weight and low PDI value. The relationships between both of the ln([M ₀]/[M]) vs. reaction time and molecular weight vs. conversion showed a straight line. The block copolymer of ODA and styrene (PODA‐b‐PSt) obtained using poly(octadecyl acrylate) (PODA) as a macro‐RAFT agent. The polymers were characterized by ¹H NMR, DSC, and gel permeation chromatograph (GPC). The effect of molar ratio [CPDB]:[AIBN] and reaction temperature on polymerization was investigated.     

Alternating copolymerization of carbon dioxide and epoxide catalyzed by an aluminum Schiff base–ammonium salt system

The alternating copolymerization of carbon dioxide (CO₂) and cyclohexene oxide (CHO) with an aluminum Schiff base complex in conjunction with an appropriate additive as a novel initiator is demonstrated. A typical example is the copolymerization of CO₂ and CHO with the (Salophen)AlMe ( 1a )–tetraethylammonium acetate (Et₄NOAc) system. When a mixture of the 1a –Et₄NOAc system and CHO was pressurized by CO₂ (50 atm) at 80 °C in CH₂Cl₂, the copolymerization of CO₂ and CHO took place smoothly and produced a high polymer yield in 24 h. From the IR and NMR spectra, the product was characterized to be a copolymer of CO₂ and CHO with an almost perfect alternating structure. The matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry analysis indicated that an unfavorable reaction between Et₄NOAc and CH₂Cl₂ and a possible chain‐transfer reaction with concomitant water occurred, and this resulted in the bimodal distribution of the obtained copolymer. With carefully predried reagents and apparatus, the alternating copolymerization in toluene gave a copolymer with a unimodal and narrower molecular weight distribution. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4172–4186, 2005     

Infrared spectroscopic analysis of poly(methyl acrylate-co-styrene)

Methyl acrylate–styrene copolymers of different copolymer compositions were free-radically prepared. The relative intensities of the carbonyl frequencies of the methyl acrylate units at v 1730 cm^?1 were correlated with the copolymer composition. The positions and shapes of the carbonyl bands in the infrared absorption spectra of the copolymers-dissolved in chloroform, were shown to depend on the composition of the copolymers and upon the presence of different proportions of methyl acrylate centered triads. The results obtained by infrared spectroscopy were compared with those obtained by ¹³C-NMR. Infrared spectra may be used to yield information about both the copolymer composition and the triad sequence distribution.     

Donor-acceptor complexes in copolymerization. L. Preparation and microstructure of chlorine-containing alternating conjugated diene–acceptor monomer copolymers

Neighboring monomer units cause significant shifts in the infrared absorption peaks attributed to cis- and trans-1,4 units in conjugated diene-acceptor monomer copolymers. Conjugated diene-maleic anhydride alternating copolymers apparently have a predominantly cis-1,4-structure, while alternating diene-SO₂ copolymers have a predominantly trans-1,4 structure. Alternating copolymers of butadiene, isoprene, and pentadiene-1,3 with α-chloroacrylonitrile and methyl α-chloroacrylate, prepared in the presence of Et_1.5AlCl_1.5(EASC), have trans-1,4 unsaturation. Alternating copolymers of chloroprene with acrylonitrile, methyl acrylate, methyl methacrylate, α-chloroacrylonitrile, and methyl α-chloroacrylate prepared in the presence of EASC-VOCl₃ have trans-1,4 configuration. The reaction between chloroprene and acrylonitrile in the presence of AlCl₃ yields the cyclic Diel-Alder adduct in the dark and the alternating copolymer under ultraviolet irradiation. The equimolar, presumably alternating, copolymers of chloroprene with methyl acrylate and methyl methacrylate undergo cyclization at 205°C to a far lesser extent than theoretically calculated, to yield five and seven-membered lactones. The polymerization of chloroprene in the presence of EASC and acetonitrile yields a radical homopolymer with trans-1,4 unsaturation.     

Benzotriazole and benzodithiophene containing medium band gap polymer for bulk heterojunction polymer solar cell applications

An alternating donor‐acceptor copolymer based on a benzotriazole and benzodithiophene was synthesized and selenophene was incorporated as π‐bridge. The photovoltaic and optical properties of polymer were studied. The copolymer showed medium band gap and dual absorption peaks in UV‐Vis absorption spectra. Photovoltaic properties of P‐SBTBDT were performed by conventional device structure. The OSC device based on polymer: PC₇₁BM (1:1, w/w) exhibited the best PCE of 3.60% with a V_oc of 0.67 V, a J_sc of 8.95 mA/cm², and a FF of 60%. This finding was supported with morphological data and space charge limited current (SCLC) mobilities. The hole mobility of the copolymer was estimated through SCLC model. Although surface roughness of the active layer is really high, mobility of a polymer was found as 7.46 × 10^?3 cm²/Vs for optimized device that can be attributed to Se?Se interactions due to the larger, more‐polarizable Se atom. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 528–535