Preparation of polymers with substituted allyl end group using dimer of α-methylvinyl monomer as addition fragmentation chain transfer agent at high temperatures

The dimerization of methyl methacrylate, ethyl methacrylate, methacrylonitrile, and α-methylstyrene to 2-substituted-1-allylic compounds [CH₂?C(X)CH₂C(CH₃)₂X] (X = COOR, C₆H₅, or CN), and methyl α-ethylacrylate to a 3-substituted-2-allylic compound [CH₃CH?C(COOCH₃)CH₂C(CH₃)(C₂H₅) COOCH₃] was carried out by catalytic chain transfer using benzylbis (dimethylglyoximato) (pyridine) cobalt (III). These dimers were then used as addition-fragmentation chain transfer agents in the polymerizations of methyl methacrylate and styrene at 80⁰C or above. Cross-dimers from methacrylic ester-α-methylstyrene and methacrylonitrile-α-methylstyrene mixtures were similarly prepared. Except for those from methyl α-ethylacrylate and methacrylonitrile, all the dimers participated in the addition-fragmentation and the copolymerization to different extents. The dimer of methyl α-ethylacrylate was actually inactive during the styrene and methyl methacrylate polymerizations. The methacrylonitrile dimer was primarily incorporated in the polymer chain through copolymerization. Among the dimer and the cross-dimers from α-methylstyrene with the other monomers, those bearing the α-methylstyrene moiety in the α-substituent [CH₂?C(X)CH₂C(CH₃)₂C₆H₅, X?COOCH₃, COOC₂H₅, and CN] are noted as highly reactive chain transfer agents. © 1994 John Wiley & Sons, Inc.     

Determination of coisotacticities of some alternating styrene–acrylic copolymers by NMR spectra

Coisotacticities σ for some alternating copolymers were determined through the analyses of their CH₃O, CH₃ and CH₂ proton NMR spectra; styrene–methyl methacrylate (σ = 0.56), styrene-methyl acrylate (σ = 0.53), styrene–methyl α-chloroacrylate (σ = 0.69), styrene–methacrylonitrile (σ = 0.19), styrene–methacrylamide (σ = 0.16), α-methylstyrene–methyl methacrylate (σ = 0.21), and α-methylstyrene–methyl acrylate (σ = 0.53) were studied. It was found that a terminal model or Bernoullian trial prevails in these complexed copolymerizations with diethylaluminum chloride. The influence of monomer structure on σ values is discussed.     

Metal-containing initiator systems. V. Radical and cationic polymerizations with initiator systems of reduced nickel and chlorosilanes

The polymerizations of methyl methacrylate, styrene, and isobutyl vinyl ether with the binary systems of reduced nickel and chlorosilanes [(CH₃)_nSiCl_4?n, n = 0–3] have been investigated. It was found that these systems could act as both radical and cationic initiators, depending on the nature of vinyl monomers used. The kinetic investigations indicated that methyl methacrylate polymerized via a radical mechanism, and the initiating activity of chlorosilanes decreased in the following order: SiCl₄ > CH₃SiCl₃ > (CH₃)₂SiCl₂ > (CH₃)₃SiCl ? 0. Cationic initiations were observed in the polymerizations of styrene and isobutyl vinyl ether. In the latter case, the activity of chlorosilanes was in the following order: (CH₃)₃SiCl > (CH₃)₂SiCl₂ > CH₃SiCl₃ ? SiCl₄. From the results obtained, a possible mechanism of selective initiation with these systems is proposed and discussed.     

Kinetics and mechanism of the addition of the phthalimid-n-oxyl radical to the double bond of vinyl compounds

The kinetics of the decomposition of the phthalimid-N-oxyl radical (PINO) in acetic acid has been studied. The rate constants of the addition of the radical to T bonds of molecules of vinyl compounds – styrene, methyl methacrylate, acrylonitrile, and methyl acrylate – have been measured. It was shown that electron-donor substituents in the monomer molecule increase, while electron-acceptor substituents decrease the rate of addition. The reactivity of monomers in the elementary step of addition of the PINO radical decreases in the order CH₂=C(CH₃)C₆H₅ > CH₂=CHC₆H₅ > CH₂=C(CH₃)COOCH₃ > CH₂=CHCOOCH₃ > CH₂=CHCN.     

Neutral Pd(II) and Ni(II) acetylide complexes as single‐component initiators for polymerizations of butyl methacrylate and acrylates

Homogeneous polymerization of butyl methacrylate (BMA) using Pd(II)‐ and Ni(II)‐based acetylide complexes as single‐component initiators has been investigated in CHCl₃ at 60°C. M(PPh₃)₂(C = CR)₂ (M = Pd, Ni; R = Ph, CH₂OH, CH₂OOCCH₃) were found to be a novel type of effective initiators for the polymerization of butyl methacrylate. Among them, Pd(PPh₃)₂(C‐CPh)₂ (PPP) shows the highest activity. Besides, PPP alone can also initiate the homogeneous polymerizations of acrylates, e. g., methyl acrylate (MA), and n‐butyl acrylate (BA). The present type of polymerization is not hindered by the incorporation of hydroquinone.     

Synthesis of Mixed-ring Zirconocene Complexes Containing Alkenyl Group and Ethylene Polymerization Catalyzed with Them

Four new mixed‐ring zirconium completes, [CH₂ = CH(CH₂)_n ‐C₅H₄](RC₅H₄)ZrCl₂ [n = l, R = CH₃OCH₂CH₂(3); n = 2, R = CH₃OCH₂CH₂ (4); n = 2, R=Me₃Si (5); n = 2, R = allyl (6)], have been prepared by the reaction of CH₂ = CH(CH₂)_n C₅H₄ZrCl₃, DME[n = l (1); n = 2 (2)] with RC₅H₄Li. When activated with methylaluminoxane (MAO), the catalytic activities of the above complexes in ethylene polymerization were tested. Complexes 5 and 6 show high activities similar to Cp₂ZrCl₂. Introduction of methoxyethyl group into Cp‐ligand dramatically decreases the catalytic activities of complexes 3 and 4, which can be overcome by increasing the amount of MAO. For complex 5, the dependence of activity and molecular weight (Mη) on the Al/Zr ratio, the polymerization time (t_P), polymerization temperature (T_P) and the polymerization solvent volume (V) was investigated.     

Controlled radical polymerization of 2‐hydroxyethyl methacrylate with a hydrophilic ruthenium complex and the synthesis of amphiphilic random and block copolymers with methyl methacrylate

A hydrophilic ruthenium complex with ionic phosphine ligands { 1 : RuCl₂[P(3‐C₆H₄SO₃Na)(C₆H₅)₂]₂} induced controlled radical polymerization of 2‐hydroxyethyl methacrylate (HEMA) in methanol under homogeneous conditions; the initiator was a chloride (R‐Cl) such as CHCl₂COPh. The number‐average molecular weights of poly(HEMA) increased in direct proportion to monomer conversion, and the molecular weight distributions were relatively narrow (M_w/M_n = 1.4–1.7). A similar living radical polymerization was possible with (MMA)₂‐Cl [(CH₃)₂C(CO₂CH₃)CH₂C(CH₃)(CO₂CH₃)Cl] as an initiator coupled with amine additives such as n‐Bu₃N. In a similar homogeneous system in methanol, methyl methacrylate (MMA) could also be polymerized in living fashion with the R‐Cl/ 1 initiating system. Especially for such hydrophobic polymers, the water‐soluble ruthenium catalyst was readily removed from the polymers by simple washing with an aqueous dilute acid. This system can be applied to the direct synthesis of amphiphilic random and block copolymers of HEMA and MMA. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2055–2065, 2002     

Vinyl polymerization. 178. Copolymerizations of p-substituted phenyl vinyl sulfides

The copolymerizations of p-substituted phenyl vinyl sulfides (M₂) having OCH₃, CH₃, H, Cl, and Br substituents with styrene and methyl methacrylate (M₁) and their intercopolymerizations at 60°C. were studied. From the results of copolymerizations with styrene and methyl methacrylate, the monomer reactivity ratios and the Q₂e₂ values were determined. For example, the Q and e values for unsubstituted phenyl vinyl sulfide were 0.45 and ?1.26 in the copolymerization with methyl methacrylate. This result indicated the importance of the 3d orbital resonance between the sulfur atom and the adjacent carbon atom in the transition state of copolymerizations. The relative reactivities of these monomers toward the polymer radicals were found to be correlated with the Hammett σ constants of the substituents. In the intercopolymerizations of these monomers, it was also found that the relative reactivities followed the Hammett equation approximately.     

Photochromic liquid crystalline structures containing azobenzene moieties

Novel liquid crystalline photochromic materials of the type 4-R-C₆H₄-N=N-C₆H₄-O(CH₂)_n-N(CH₂CH₂OH)₂, where R is NO₂, H, CN, O-n-C₈H₁₇, phenyl, 4-O₂NC₆H₄, were prepared. Some of them are photoconductive. These materials were used for the preparation of light-sensitive polymers in which the photoactive moieties were attached to polyurethane chain. Photochromism of these compounds is based on trans-cis isomerization of azobenzene group. An example of the photochromic activity is presented on solid solution of one material (R = O-n-C₈H₁₇, n = 5) in poly(methyl methacrylate) matrix.     

Synthesis of well‐defined cyclodextrin‐core star polymers

The synthesis of 21‐arm methyl methacrylate (MMA) and styrene star polymers is reported. The copper (I)‐mediated living radical polymerization of MMA was carried out with a cyclodextrin‐core‐based initiator with 21 independent discrete initiation sites: heptakis[2,3,6‐tri‐O‐(2‐bromo‐2‐methylpropionyl]‐β‐cyclodextrin. Living polymerization occurred, providing well‐defined 21‐arm star polymers with predicted molecular weights calculated from the initiator concentration and the consumed monomer as well as low polydispersities [e.g., poly(methyl methacrylate) (PMMA), number‐average molecular weight (M_n) = 55,700, polydispersity index (PDI) = 1.07; M_n = 118,000, PDI = 1.06; polystyrene, M_n = 37,100, PDI = 1.15]. Functional methacrylate monomers containing poly(ethylene glycol), a glucose residue, and a tert‐amine group in the side chain were also polymerized in a similar fashion, leading to hydrophilic star polymers, again with good control over the molecular weight and polydispersity (M_n = 15,000, PDI = 1.03; M_n = 36,500, PDI = 1.14; and M_n = 139,000, PDI = 1.09, respectively). When styrene was used as the monomer, it was difficult to obtain well‐defined polystyrene stars at high molecular weights. This was due to the increased occurrence of side reactions such as star–star coupling and thermal (spontaneous) polymerization; however, low‐polydispersity polymers were achieved at relatively low conversions. Furthermore, a star block copolymer consisting of PMMA and poly(butyl methacrylate) was successfully synthesized with a star PMMA as a macroinitiator (M_n = 104,000, PDI = 1.05). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2206–2214, 2001     

Multifunctional coupling agents for living cationic polymerization. IV. Synthesis of end-functionalized multiarmed poly(vinyl ethers) with multifunctional silyl enol ethers

Telechelic ( 8 ) and end-functionalized four-arm star polymers ( 9 ) were synthesized through the coupling reactions of end-functionalized living poly(isobutyl vinyl ether) ( 5; DP _n ～ 10) with the bi-and tetrafunctional silyl enol ethers, H_4-nC? [CH₂OC₆H₄C(OSiMe₃) = CH₂]_n ( 3: n = 2; 4: n = 4). The precursor polymers 5 were prepared by living cationic polymerization with functionalized initiators, CH₃CH(Cl)OCH₂CH₂X(6), in conjunction with zinc chloride in methylene chloride at ?15°C. The initiators 6 were obtained by the addition of hydrogen chloride gas to vinyl ethers bearing pendant functional groups X , including acetoxy [? OC(O)CH₃], styryl (? OCH₂C₆H₄-p-CH = CH₂), and methacryloyl [? OC(O)C(CH₃) = CH₂]. The coupling reactions with 3 and 4 in methylene chloride at ?15°C for 24 h afforded the end-functionalized multiarmed polymers ( 8 and 9 ) in high yield (>91%), where those with styryl or methacryloyl groups are new multifunctional macromonomers. © 1994 John Wiley & Sons, Inc.     

Mass spectra of some neopentylphosphorus derivatives

The fragmentation patterns and major metastable ions of the mass spectra of the neopentyl-phosphorus derivatives [(CH₃)₃CCH₂]₃P, [(CH₃)₃CCH₂]₂P(O)H, [(CH₃)₃CCH₂]_nPX_3-n (n = 1 and 2; X = H, Cl, C₆H₅ and CH = CH₂), [(CH₃)₃CCH₂]₃PS, [(CH₃)₃CCH₂]_nP(S)R_3-n (n = 1 and 2; R = C₆H₅ and CH = CH₂), [(CH₃)₃ CCH₂]₂PCH₂CH₂P[CH₂C(CH₃)₃]₂, ([CH₃)₃CCH₂]₂PCH₂PCH₂-CH₂P(H)C₆H₅ and [(CH₃)₃CCH₂]₂PCH₂CH₂P(S)(CH₃)₂ are described. Fragmentation of a neopentyl group by elimination of either C₄H₈ or CH₃ is very favourable when the neopentyl group is bonded to either a tricoordinate or tetracoordinate phosphorus atom. In neopentylphosphines with two or three neopentyl groups, stepwise elimination of C₄H₈ from all of the neopentyl groups occurs very readily. The resulting [(CH₃)_nPX]^+._3-n ions are often the most intense ions in the mass spectra.     

Emulsion copolymerization of styrene and methyl methacrylate

Chain transfer constants to monomer have been measured by an emulsion copolymerization technique at 44°C. The monomer transfer constant (ratio of transfer to propagation rate constants) is 1.9 × 10^?5 for styrene polymerization and 0.4 × 10^?5 for the methyl methacrylate reaction. Cross-transfer reactions are important in this system; the sum of the cross-transfer constants is 5.8 × 10^?5. Reactivity ratios measured in emulsion were r₁ (styrene) = 0.44, r₂ = 0.46. Those in bulk polymerizations were r₁ = 0.45, r₂ = 0.48. These sets of values are not significantly different. Monomer feed compcsition in the polymerizing particles is the same as in the monomer droplets in emulsion copolymerization, despite the higher water solubility of methyl methacrylate. The equilibrium monomer concentration in the particles in interval-2 emulsion polymerization was constant and independent of monomer feed composition for feeds containing 0.25–1.0 mole fraction styrene. Radical concentration is estimated to go through a minimum with increasing methyl methacrylate content in the feed. Rates of copolymerization can be calculated a priori when the concentrations of monomers in the polymer particles are known.     

ALKALI-PHOSPHORVERBINDUNGEN UND IHR REAKTIVES VERHALTEN LXXIV Synthese und Reaktionsverhalten von Alkylen-bis-alkylphosphinen

Abstract

Alkylen-bis-phosphine H₂P-(CH₂)nPH₂ (n=2, 3, 4) lassen sich unter geeigneten Bedingungen zu H(M)P-(CH₂ n- PH₂ und H(M)P-(CH₂)n-P(M)H metallieren und nach Umsatz mit Alkylhalogeniden in die entsprechenden Phosphine HRP-(CH₂)n-PH₂ sowie HRP-(CH₂)n-PRH überführen. Letztere sowie deren Alkaliphosphide sind Ausgangabasis für die Synthese von P-E-P-Heterocyclen (E=Mg, C, Si, Ge) mit 5, 6 und 7-Ringstruktur. Der Reaktionsverlauf zwischen BuLiP-(CH₂)₃-PLiBu und CH₂C1₂ wird diskutiert. Die Struktur der dargestellten Verbindungen wird NMR- und massenspektrokopisch gesichert.

The metallation of alkylen-bis-phosphines H₂P-(CH₂)nPH₂ (n=2, 3, 4) under suitable conditions leads to H(M)P-(CH₂)n-PH₂ and H(M)P-(CH₂)n-P(M)H which reacts with alkylhalides forming the corresponding phosphines. The latter and their alkaliphosphides, respectively, are suitable materials to prepare P-E-P-heterocycles (E=Mg, C, Si, Ge) of 5, 6 and 7-ring structure. The structure of the synthesized compounds is elucidated by investigation of their mass and ³¹P-nmr-spectra.     

ESR studies of the radiation-induced multiple graft polymerization

The radiation-induced multiple-graft polymerization was studied by an ESR method. When methyl methacrylate vapor was introduced onto preirradiated polyethylene already grafted with styrene, the second step of grafting of methyl methacrylate occurred mainly in the polyethylene portion. The kinetic treatment proved that the termination rate constant k_t of methyl methacrylate decreased with the amount of styrene grafted in advance. On the other hand, when styrene vapor was introduced onto polyethylene grafted with methyl methacrylate, only radicals of poly(methyl methacrylate) decreased. In this case, the second step of grafting of styrene occurred in the poly-(methyl methacrylate) portion which covered the whole surface of the polyethylene powder. When monomer vapors were alternately introduced onto preirradiated polyethylene powder, the second step of grafting occurred at the growing chain end of the first monomer.     

Chain-transfer constant of fluoroalcohols

Chain transfer constants of some fluoroalcohols [HCF₂(CF₂)_n?1CH₂OH, n = 2, 4, 6] in the catalyzed polymerization of vinyl acetate, styrene, acrylonitrile, and methyl methacrylate at 60°C have been evaluated by a method based on degree of polymerization. Since fluoroalcohols are normally nonsolvents for polymers, a homogeneous reaction phase is maintained by carrying out the polymerization in benzene (except in case of acrylonitrile, where no solvent was used). The transfer constants vary, depending on the reactivity as well as the polarity of the radicals, in the following order: vinyl acetate > styrene > methyl methacrylate > acrylonitrile. Of the three fluoroalcohols studied, the transfer constants increase with the increasing value of n. The results have been interpreted in terms of polar structure contribution in the transition state of the transfer reactions.     

Effect of the Nature of the Polymer Matrix on the Luminescence of Tb(III) Complexes with β-Diketone Copolymers

The formation conditions and luminescence of Tb(III) complexes with synthesized copolymers of unsaturated acetylacetone derivatives with styrene and methyl methacrylate were studied. The luminescence intensity of these Tb(III) complexes was found to depend on the β-diketone substituent nature (CH₃, CF₃, C₆H₅) and structure (linear, branched) and the β-diketone to monomer ratio in the polymerizing mixture.     

Polymerization of mono‐, Di‐, and trichloroethyl methacrylates: A study in chain transfer

Bulk free radical polymerization of the monomer series CH₂ = C(CH₃)C(O)OCH₂CH_3‐n Cl_n , n = 1, 2, 3, yields an unexpectedly crosslinked product with a crosslink density that increases with decreasing chlorine content of the respective monomer (n = 3 < n = 2 < n = 1). This chlorine substituent effect is investigated by correlation with chain transfer constant measurements for four homologous series of chloroalkyl compounds (chloroethyl acetates (CH₃C(O)OCH₂CH_3‐n Cl_n , n = 1,2,3); chloromethanes (CH_4‐n Cl_n , n = 2,3,4) and CD₂Cl₂ and CDCl₃ analogs; butyl chloride isomers (n‐ , iso‐ , sec‐, tert‐) and tert‐C₄D₉Cl analog; and nine chloroethanes (C₂H_{n ?6}Cl_n , n = 1–6)) in a methyl methacrylate polymerization. The pattern conveyed by the magnitude of chain transfer constants and deuterium isotope effects is consistent with a vicinal chlorine effect (i.e., chlorine activation of a vicinal hydrogen for abstraction) to account for the relative activities of the four series of model compounds and for the propensity of the chloroethyl methacrylates to crosslink in a bulk free radical polymerization. The chloroalkyl moiety's contribution to chain transfer is relatively modest (≤10^?4), but, when incorporated as a monomer pendant group in free radical polymerizations, it is effective in broadening molecular weight to the extent of resulting in a crosslinked polymer. Published 2016.^? J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 93–106     

Fluorescent polymer particles by emulsion and miniemulsion polymerization

We describe the synthesis and characterization of latex particles labeled with a brightly fluorescent yellow dye (HY) based on the benzothioxanthene ring structure. Three dye derivatives were synthesized with different spacers connecting the HY nucleus to a methacrylate group. For one of the dyes (HY2CMA, r_A), we show that the reactivity ratios with styrene (r_A = 0.71, r_B = 0.25) and butyl methacrylate (r_A = 0.87, r_B = 0.14) should lead to random dye incorporation if the amount of dye in the feed is small. Seeded emulsion polymerization fails to lead to significant dye incorporation unless large amounts of nonionic surfactant are present. In contrast, miniemulsion polymerization worked well to yield latex particles of polystyrene, poly(butyl methacrylate), and poly(methyl methacrylate) with high monomer conversion and essentially quantitative dye incorporation. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 766–778, 2003     

Living cationic polymerization of vinyl ethers with carboxylic acid/tin tetrahalide initiating systems. II. Effects of steric hindrance of carboxylate counteranions

Effects of steric crowding of the substituent of carboxylate counteranions on living cationic polymerization of isobutyl vinyl ether (IBVE) were investigated with the use of two series of carboxylic acids with various carbonyl substituents [RCOOH; R = (aliphatic series) CH₃CH₂, (CH₃)₂CH, (CH₃)₃C; (aromatic series) C₆H₅CH₂, (C₆H₅)₂CH, (C₆H₅)₃C] in conjunction with tin tetrabromide (SnBr₄) and 1,4-dioxane (DO) in toluene at 0°C. The overall polymerization rate increased with increasing the bulkiness of the substituents R in both the series: R = CH₃ (1) ≃ CH₃CH₂ (1) < (CH₃)₂CH (1.76) < (CH₃)₃C (2.31); C₆H₅CH₂ (0.84) < (C₆H₅)₂CH (0.98) < (C₆H₅)₃C (1.74); the values in the parentheses show the relative polymerization rate. In all the polymerizations, the number-average molecular weight (M_n) of the polymers was directly proportional to monomer conversion and in good agreement with the calculated values, assuming that one RCOOH molecule forms one polymer chain. The living nature of these polymerizations was further confirmed by a linear increase in M_n of the polymers upon sequential addition of a fresh monomer feed to the almost completely polymerized reaction mixtures. In the polymerizations with sterically less hindered carboxylic acids [R = CH₃CH₂, (CH₃)₂CH, C₆H₅CH₂, (C₆H₅)₂CH], the molecular weight distribution (MWD) of the polymers was very narrow (M_w/M_n < 1.1) throughout the polymerizations. In contrast, with bulkier substituent-containing counterparts [R = (CH₃)₃C, (C₆H₅)₃C], the polymerizations led to the polymers of relatively broad MWD (M_w/M_n ≅ 1.5 at ca. 100% monomer conversion). The bulky substituents such as (CH₃)₃C and (C₆H₅)₃C may decrease the interconversion rate between a dormant and an active species and increase the time-average concentration of the active growing species. The stereoregularity of the obtained polymers was not changed much with the steric environment of the counteranion (meso: 66–69%). © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2923–2932, 1999