George B. Butler

Characterization of the Charge Transfer Complex from Furan and Maleic Anhydride and the Alternating Copolymer

Abstract A previously unreported copolymer between furan and maleic anhydride was readily obtained by free radical initiation of benzene solutions of the comonomers. The product copolymers exhibit remarkably uniform composition regardless of monomer feed ratios. A donor-acceptor complex was suspected to account for the 1:1 alternating sequence of the monomers in the product. The complex was easily detected and partially characterized, although its exact role in the mechanism is uncertain.

The Fundamental Basis for Cyclopolymerization. IV. Radiation Initiated Solid-State Polymerization of Certain Dimethacrylamides

Abstract The purpose of this investigation was to study the solid-state polymerization of suitable 1,6-diene monomers, to compare the structure of the polymers with those obtained by free radical initiated solution polymerization, and to use this information in postulating the most probable conformation of the monomer in the crystal. An additional purpose was to compare the polymerization characteristics of these dienes with suitable monoolefinic counterparts. The compounds studied were dimethacrylamide, N-isobutyryl-methacrylamide, and their N-methyl and N-phenyl derivatives. Solution polymerization of all monomers and solid-state polymerization of solid monomers (N-methyl- and N-phenyl-N-isobutyrylmethacrylamide were liquids which did not polymerize) led to polymers of comparable structure in each case. Dimethacrylamide yielded a polymer consisting primarily of six-membered rings. N-Methyldimethacrylamide gave a polymer consisting predominantly of five-membered rings but up to 30= six-membered rings. N-...

The Stereochemistry of Styrene-Maleic Anhydride Copolymers: 13C-NMR Study and Pvcilo and Indo/1 Calculations

Abstract The stereochemistry of alternating copolymers of styrene (ST) with maleic anhydride (MA) was examined by 13C-NMR spectroscopy, and the stabilization energies and the most stable geometries of complexes and adducts between ST and MA were calculated by the PVCILO program and by INDO/1. The methine and carbonyl carbon atoms of the MA portion and the quaternary carbon atom of the ST portion reveal different stereochemistries due to various polymerization conditions, suggesting that the donor-acceptor complex may participate in the co-polymerization. The complex postulated according to the Diels-Alder geometry was more stable than that according to [2+2] cycloaddition geometry. It is believed that the stabilization energy is so great that the copolymerization occurs spontaneously via forming a donor-acceptor complex and adducts. The geometries of 1:1 adducts formed by endo and exo approaches in the Diels-Alder geometry mode were also calculated.

Chemical Reactions on Polymers. II. Modification of Diene Polymers with Triazolinediones via the Ene Reaction

Abstract A wide variety of polymers and copolymers of 1,3-dienes have been modified at low temperatures via the ene reaction with 4-substituted l,2,4-triazoline-3,5-diones. The resulting modified polymers were characterized via infrared spectroscopy, nuclear magnetic resonance, intrinsic viscosity, gel-permeation chromatography, differential scanning calorimetry, solubility tests, and tensile measurements. Physical properties measurements support the postulate that the highly polar pendant urazole groups contribute inter molecular and intramolecular hydrogen-bonding interactions and thus impart to the modified polymers thermoplastic elastomer properties. Changes in the solubility character, thermal behavior, and tensile properties of the modified polymers are in accord with this postulate. Since the association between molecules is physical in nature, the modified polymers remain soluble in appropriate solvents. They also show dramatic decreases in molecular size; for example, the average molecular size o...

A Bimolecular Alternating Inter-Intramolecular Chain Propagation Leading to Cyclocopolymerization

Abstract This paper includes a report of the original studies which led to postulation of the cyclocopolymerization mechanism. Conditions for the copolymerization experiments, involving copolymerization of a wide variety of 1,4-dienes and alkenes, are reported in addition to the spectral and analytical evidence obtained in support of the proposed structures. Also included are some of the physical properties of the copolymers and some additional chemical evidence in support of the structures.

Studies in Cyclocopolymerization. IX. A Systematic Kinetic Study on the Cyclocopolymerization of Vinyl Ethers with Maleic Anhydride in Different Solvents

Abstract The kinetics of the AIBN-initiated copolymerization of divinyl ether (DVE) and ethyl vinyl ether (EVE) with maleic anhydride (MA) was extensively studied in seven different solvents. The yield at 100% conversion as a function of the feed composition when the total monomer concentration is kept constant gave a confirmation of the composition of these copolymers: DVE/MA=½ and EVE/MA=1/1. The study of the initial rate as a function of the feed composition made it possible to determine the relative values of the different propagation rate constants consistent with a mechanism by successive and selective additions: in the EVE-MA system, the addition of EVE is slower than the addition of MA; in the DVE-MA system, the addition of DVE is slower than the addition of the first MA molecule, while the addition of the second MA molecule is slower than the first one. The study of the dependence of the monomer concentration, of the AIBN concentration, and of the efficiency of the initiator, on the rate of polym...

Studies in Cyclocopolymerization. VIII. Solvent Effects in Cyclocopolymerization of Maleic Anhydride with Divinyl Ether

Abstract Solvent effects in the cyclopolymerization of maleic anhydride (MA) with divinyl ether (DVE) were systematically studied. Evidence is presented which supports a charge-transfer (CT) complex formed between the comonomers as the active species in the cyclocopolymerization. The equilibrium constants (K) of CT complexation with MA was measured in n-heptane by UV spectrophotometry for tetra-hydrofuran, ethyl vinyl ether, DVE, furan, and dihydropyran. K-values increased in the above order. K of the MA-DVE pair was measured by UV and NMR in polyhaloalkanes as solvents. K-values decreased with increase of the dielectric constant of the solvent. The rate of copolymerization and number-average molecular weights decreased in more polar solvents. The initial rate was about 100 times faster in CHCl3 than in DMF. In dilute solution, [M1 + M2]=0.57 mole/liter, the initial overall rate of copolymerization was maximum in DVE-rich feed in CHC13, CH2C12, and DMF. Kinetical derivation failed to explain the rate prof...

The Fundamental Basis for Cyclopolymerization. I. Unconjugated Chromophoric Interactions Related to Cyclopolymerization

Abstract A far ultraviolet study showed progressive bathochromic wavelength shifts within the following series of compounds: (i) allyltrimethylsilane, diallyldimethylsilane, triallylmethylsilane, tetraallylsilane; (ii) allyltripropylsilane, diallyldipropylsilane, triallylpropylsilane; (iii) 4,4-dimethyl-1-pentene, 4,4-dimethyl-1,6-heptadiene, 4-allyl-4-methyl-1,6-heptadiene. In the series tri-methylvinylsilane, dimethyldivinylsilane, methyltrivinylsilane, and tetravinylsilane, trimethylvinylsilane was shifted bathochromically from the rest of the vinylsilanes, which were grouped together. Allyldimethylvinylsilane showed two independent absorptions.

Chemical Reactions on Polymers. 111. Modification of Diene Polymers via the Ene Reaction with 4-Substituted-1,2,4-triazoline-3,5-diones

Abstract Various diene polymers have been modified at room temperature via the ene reaction with 4-substituted-1,2,4-triazoline-3,5-diones. The resulting modified polymers were characterized by means of IR spectroscopy, nuclear magnetic resonance, differential scanning calorimetry, and solubility tests. Physical properties measurements support the assumption that the highly-polar pendant urazole groups play an important role in both inter-molecular and intramolecular hydrogen bonding interaction, and accordingly give thermoplastic properties to the modified polymers. Changes in the thermal analysis and solubility character of the modified polymers agree fairly well with this assumption. The modified polymers remain soluble in suitable solvents because of the physical nature of the association between molecules.

Studies in Cyclocopolymerization. XIV. Cyclocopolymerization Study of Certain Maleoylamino Acids with Divinyl Ether

Abstract N-Carbethoxymaleimide (I), a convenient intermediate to maleoylamino acids in aqueous solution, also undergoes facile reaction with amines in ether. Thermolyses of the resulting imide-amides at 170-180°C gave N-substituted maleimides. N,N-Dimethyl-l,3-propanediamine reacted with I to give XI directly. Copolymers prepared and studied were those of divinyl ether with N-carbethoxymaleimide, maleoylglycine, maleoyl-DL-alanine, maleoyl-DL-phenylalanine, maleoyl-L-phenylalanine, maleoyl-DL-methionine and maleoyl-DL-leucine. These copolymers were characterized by elemental analyses to establish the comonomer ratios, by viscosity measurements, and in certain instances by determination of molecular weight by membrane osmometry after esterifica-tion with diazomethane.