Cationic polymerization of β-pinene,styrene and α-methylstyrene

Molecular weight distributions determined by gel permeation chromatography demonstrate that α-methylstyrene copolymerizes with both β-pinene and styrene, forming both bi- and terpolymers. The composition of precipitated polymer versus crude polymer, as determined by nuclear magnetic resonance, suggests that β-pinene and styrene also copolymerize. Extraction of the latter bipolymer of β-pinene and styrene with acetone gives only a small amount of insoluble β-pinene homopolymer, confirming that β-pinene and styrene copolymerize in m-xylene. GPC analysis shows that each copolymer contains some homopolymer. A comparison of M _n with molecular weight calculated from NMR analysis, assuming chain transfer to solvent, indicates that chain transfer is the predominant method of forming dead polymer. The carbonium ions of the growing chain tend to transfer to solvent with increasing ease in the order β-pinene, styrene, and α-methylstyrene.     

Polymer effect in graft polymerizations of acrolein onto imidazole-containing polymer

The graft polymerizations of acrolein (AL) onto an imidazole (Im)-containing polymer, such as a homopolymer of 4(5)-vinylimidazole (VIm) and several copolymers of VIm-4-vinylpyridine (VPy), VIm-1-vinyl-2-pyrrolidone (VPr), and VIm-styrene (St), have been studied in ethanol at 0°C. The degree of polymerization (P?_n) of the resulting polyacrolein graft depended on the number of Im units in the Im-containing polymer which produced a decrease in P?_n of grafted polyacrolein. The P?_n of the graft polyacrolein was determined to be in the range of 5-23. The rate of polymerization (R_p) was expressed by R_p = k(PVIm) (AL)². The graft polymerizability of the AL was influenced by the comonomer in the parent polymer, and was found to be in the order of VIm homopolymer > VIm-VPr copolymer > VIm-VPy copolymer > VIm-St copolymer. R_p was affected by the functional group around the Im group in the Im-containing polymer. These results were discussed by assuming the conformation of the parent polymer in ethanol.     

Effect of solvent power on the adsorption of polystyrene onto a metal surface

The adsorption of linear polystyrenes from cyclohexane solutions onto a chrome plate of 35 (the theta temperature), 40, and 45°C was studied by ellipsometry. The adsorbance decreases with increasing temperature, while the extension of the adsorbed polymer layer increases. The adsorbance is almost independent of the molecular weight at these temperatures. The slope of a double logarithmic plot of extension versus molecular weight is 0.5 at the theta temperature, whereas at the higher temperatures the slope is a little larger. Both the adsorbance and the extension of the adsorbed layer change reversibly over a cycle of temperature change, indicating that a reversible conformational change has occurred. The expansion factor α_t of the adsorbed layer is compared with the theoretical predictions of Hoeve and of Jones and Richmond. The expansion factor α_t according to Hoeve's theory, was smaller than the measured value, whereas the expansion calculated by the Jones–Richmond theory is much larger than the measured value. It is concluded that the tail portions of adsorbed chains predominantly govern the extension of the adsorbed layer.     

Dilute solution properties of styrene–acrylonitrile and styrene–methyl methacrylate copolymers. II. Short-range and long-range interactions from intrinsic viscosity data

Experimental data on styrene–acrylonitrile (St–AN), and styrene–methyl methacrylate (St–MMA) copolymers reported in Part I of this series are tested by “two-parameter” theoretical relations. The Fox–Flory (F–F) parameter K is estimated using the F–F, Stockmayer–Fixman (S–F), and Inagaki–Ptitsyn (I–P) equations. In general, the K values obtained by the F–F equation are low for the three St–AN copolymer samples in the systems studied while the values obtained from S–F and I–P equations agree within the limits of experimental error. Values of K obtained from Kurata–Stockmayer (K–S) equation for sample SA₁ agree with values obtained by the S–F and I–P equations. The specific solvent effect on the K values is discussed. Values of the unperturbed dimension r?0²/M?_w, calculated from the K values estimated from the S–F equation and from the homopolymer data are compared. Except in one case, the calculated r?0²/M?_w values from homopolymer data are low in comparison with the values obtained from experimental data, which shows that the presence of the repulsive interactions between unlike monomer units brings about an expansion of copolymer molecule. The effect of composition on the steric factor σ values is discussed. The long-range interaction parameter B, the excess interaction parameters ΔB_AB, and χAB are calculated. The effects of composition and solvent on these parameters are discussed.     

Fluorescence probes for polymerization reactions: Bulk polymerization of styrene,n-butyl methacrylate,ethyl methacrylate,and ethyl acrylate

Julolidine malononitrile 3 was used as a fluorescent probe for high-conversion (free-radical) bulk polymerization of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, ethyl acrylate, styrene, and the copolymerization of styrene/n-butyl methacrylate. The fluorescence of the probe increased gradually as polymer conversion increased. This was followed by an abrupt rise in fluorescence intensities by a factor of 3 to 40 depending on the polymer formed. Finally the fluorescence intensities leveled off as the polymer limiting conversion was reached. The polymerization region in which fluorescence intensity increases sharply seems to correspond to the increase of the rigidity of the medium at the glass transition. A correlation between the limiting quantum yield of fluorescence of the dye and the polymer glass transition T_g and expansion coefficient α was found. These results were interpreted in terms of rotation-dependent nonradiative decay which links the excited-state conformation to the rigidity of the medium.     

First-order excluded-volume effect on the intrinsic viscosity of nondraining polymer coils

For a nondraining polymer coil in the vicinity of the theta temperature the cube of the viscosity expansion factor α_η may be expanded in powers of the excluded-volume parameter z as α_η³ = 1 + C₁z + C₂z² + ···. No exact values of the coefficients C₁, C₂, ···, are as yet known. This paper aims at evaluating C₁ by the Kirkwood–Riseman formalism of polymer hydrodynamics with no mathematical approximation. The analysis gives C₁ = 1.29, which is much smaller than 1.55 derived on the basis of the same formalism by Kurata and Yamakawa. The approximations used by these authors are discussed by comparison of their analysis with the present one. The first-order excluded-volume effect on the translational friction factor is also evaluated in the same way as for the intrinsic viscosity, and the result is shown to agree quite closely with the exact value determined by Stockmayer and Albrecht.     

New telechelic polymers and sequential copolymers by polyfunctional initiator-transfer agents (inifers). III. Synthesis and characterization of poly(α-methylstyrene-b-isobutylene-b-α-methylstyrene)

The synthesis of a new glassy-rubbery-glassy triblock copolymer poly(α-methylstyrene-b-isobutylene-b-α-methylstyrene) has been demonstrated. The key to the synthesis was the preparation by inifer method of a perfectly bifunctional polyisobutylene which carries tert-chlorine end groups Cl-PIB-Cl. In conjunction with Et₂AlCl coinitiator, the telechelic Cl-PIB-Cl molecule initiates the polymerization of α-methylstyrene at both ends of the prepolymer. Triblock composition can be controlled by the judicious selection of synthesis conditions; that is, Cl-PIB-Cl molecular weight, α-methylstyrene concentration, and solvent polarity. Theoretical triblock M _n calculated from M _n of Cl-PIB-Cl and triblock overall composition is in excellent agreement with experimental M _n which indicates negligible homopolymer contamination. Extraction with a series of hydrocarbon solvents reveals broad composition distribution. The stress-strain profile of a triblock is similar to that of a poly(styrene-b-butadiene-b-styrene) thermoplastic elastomer of similar composition.     

Gel permeation chromatography: Examination of column efficiency

Gel permeation chromatographic (GPC) separations have been performed with several commercially available column packing materials. The results have been analyzed in the conventional manner to obtain the ratio of weight average to number-average molecular weight, M_w/M_n, for solutes with narrow molecular weight distribution. Various other parameters proposed to measure the efficiency of GPC columns have been evaluated and compared. It is proposed that the experimentally determined value of M_w/M_n for a series of different molecular weight samples with similar, narrow distribution for a given set of columns is a convenient parameter for comparing column efficiency in GPC. This parameter may be calculated from a single chromatogram unlike resolution, R, resolution index, RI, or specific resolution, RS, which require a pair of chromatograms. Results from the M_w/M_n method are usually in agreement with those from the R, RI, and RS calculations but one exception has been found. The number of theoretical plates calculated from the elution of a small molecule or from the polymer peak bears little relation to efficiencies predicted from the proposed M_w/M_n method or from R, RI, or RS.     

Excluded volume study of a sulfonate-containing polyelectrolyte in salt solutions

Chain characteristics of a linear sulfonate-containing homopolymer, sodium poly(3-methacryloyloxypropane-1-sulfonate), in aqueous salt solutions (ionic strength, C_s = 0.01N to 5N NaCl) have been investigated by light scattering and intrinsic viscosity. The molecular weight (M?_w)–viscosity relation can be well described by the Mark–Houwink and the Stockmayer–Fixman equations. The coil is highly expanded even in the most concentrated NaCl solution (6N), and no 1:1 electrolyte was found to precipitate this polymer. A linear relation was observed between the viscosity expansion factor, α^3η, and (M?_w/C_s)^1/2. Examination of the data in terms of theories for excluded volume and hydrodynamic interaction suggests that the coil experiences dominant hydrodynamic interaction, corresponding to a nondraining coil, and the second virial coefficient and coil expansion at high C^s can be correlated by the Flory–Krigbaum–Orofino equation. Results for this polymer are compared with those for other polyelectrolytes, and are discussed in terms of chain structure, flexibility, and hydrophobicity.     

Conformational and neighboring effects in graft polymerization of acrolein onto imidazole-containing polymer

The graft polymerizations of acrolein (AL) onto an imidazole (Im)-containing polymer, such as a homopolymer of 4(5)-vinylimidazole (VIm) and several copolymers of VIm-methyl vinyl ketone, VIm-butyl acrylate, and VIm-2-ethyl hexyl acrylate, have been kinetically carried out in ethanol-water mixture at 0°C. The graft polymerization rate R_p and the degree of graft polymerization increased with increasing concentration of water in the solvent. Moreover, the R_p of the copolymer system having the hydrophobic group as the side chain decreased in comparison with the homopolymer system. Polymerizations of AL in the presence of propionamide or poly-acrylamide (AAm) induced by Im were also kinetically carried out in ethanol-water mixture. The R_p was also affected by the conformational change of poly-AAm. These results were discussed by assuming the conformation of the parent polymer in ethanol-water mixture.     

A semiempirical formulation for the study of molecular interactions

The coefficients of a 1/R expansion (containing long-range electrostatic interaction, medium-range electrostatic-induced dipole attraction, short-range dispersive attraction, and very short overlap interaction terms) have been determined, within a semiempirical approach, from the results of a priori calculations. The formulation has been applied to the study of the stable conformations of benzene complexes.     

Equilibrium anionic polymerization of α-methylstyrene in p-dioxane

The equilibrium anionic polymerization of α-methylstyrene in p-dioxane, with potassium as initiator, has been investigated at 5, 15, 25, and 40°C by using high-vacuum techniques. The comparison of these results with those obtained previously for the equilibrium polymerization of α-methylstyrene in tetrahydrofuran revealed that, although the values of ΔG_1c, the free-energy change upon the polymerization of 1 mole of liquid monomer to 1 bases-mole of liquid amorphous polymer of infinite chain length, are the same for both systems, there is a distinct effect of the solvent. This effect is reflected in the value of monomer equilibrium concentration and its variation with polymer concentration and is explained in terms of a solvent–monomer and solvent–polymer interaction parameter.     

Tuning block copolymer phase behavior with a selectively associating homopolymer additive

We use polymer random phase approximation (RPA) theory to calculate the microphase separation transition (MST) spinodal for an AB + C diblock copolymer–homopolymer blend where the C homopolymers are strongly attracted to the A segment of the copolymers. Our calculations indicate that one can shift the MST spinodal value of the A ? B segmental interaction parameter (χ_ABN)_S to significantly lower values [i.e., (χ_ABN)_S < 10.5] upon the addition of a selectively attractive C homopolymer. For a sufficiently attractive C homopolymer, (χ_ABN)_S can be pushed to negative values, indicating microphase separation in what would appear to be a completely miscible diblock copolymer. Furthermore, we show that microphase separation can occur in diblock copolymer–homopolymer blends where the segmental interactions between all polymer constituents are attractive. By tuning the value of (χ_ABN)_S with a homopolymer additive, one is therefore able to tune the effective copolymer segregation strength and thus dramatically affect the blend phase behavior. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2083–2090, 2009     

Orientational order in liquid normal alkanes: An investigation using gas-chromatographic data

Using retention voluems, obtained from gas-liquid chromatography with then-alkanesn-C₂₈,n-C₃₂, andn-C₃₆ and the branched alkane squalane (2,6,10,15,19,23-hexamethyltetracosane) as the solvents and small branched andn-alkane molecules as solutes, excess chemical potentials were determined at 80, 100, and 120°C. From these data Flory'sX ₁₂ parameter was calculated, which is related to differences in force field and in orientatinal order of the two compounds. After correction for end effects, theX ₁₂ parameter in then-alkane solvents appeared to decrease with rising temperature and to increase with increasing chain length of then-alkane solvent. In addition,X ₁₂ was dependent on the shape of the order-disturbing substance. These results all point to the presence of short-range orientational order in liquidn-alkanes, which was deduced to occur before from enthalpies of mixing by Patterson and from depolarized Rayleigh scattering by Bothorel. In addition, it is shown that theX ₁₂ values are influenced by coupling of torsional oscillations of the molecules of the mixture components.     

Stereospecific polymerization of α-methylstyrene by friedel-crafts catalysts

The relationship between stereoregularity and polymerization conditions of α-methylstyrene has been studied by means of NMR spectra. The effects of solvents and various Freidel-Crafts catalysts have been investigated. The stereoregularity of poly-α-methylstyrene increased with increased polymer solubility in the solvent used and with decreasing polymerization temperature. This behavior is completely different from the stereospecific polymerization of vinyl ethers and methyl methacrylate in homogeneous systems. This may be due to the strong steric repulsion exerted by the two substituents in the α-position of α-methylstyrene. For example, with BF₃ · O(C₂H₅)₂ as catalyst at ?78°C., atactic polymer is obtained in n-hexane, a nonsolvent for α-methylstyrene, whereas highly stereoregular polymer is produced in toluene or methylene chloride, good solvents for the polymer. However, the polarity of the solvent and the nature of the catalyst hardly affect the stereoregularity of the polymer.     

Polymer swelling. XXV. Structure‐affinity correlation studies that involve poly(styrene‐co‐divinylbenzene) exposed to acetylenic liquids

The adsorption parameters (α) established for the monosubstituted acetylenic liquids in this investigation are consistent with expectation based on analogies with the log α_f = log α_i ‐ D_s(N_f − N_i) relationships reported earlier for the many homologous series of liquids ZR, in which Z is a functional group having strong affinity for the pendent phenyl group of polystyrene and R is an alkyl substituent that is varied systematically. The order of relative Z‐affinities, based on α for the respective ZCH₂CH₃ molecules, confirm that the nature of Z is the major factor that affects α and that electronic and steric contributions from R are modifying effects, which are reflected in D_s. Comparisons of the results observed for HCC(CH₂)_nZ′ liquids with those for HCC(CH₂)_nH and with analogous pairs of Z(CH₂)_nZ′ series confirm that Z′ at the other end of the polymethylene chain can have a moderate positive effect or a marked negative effect on α, depending on whether the mode of adsorption to pendent phenyl groups is mono‐ or bidentate. This study also confirms that a sharp reversal in the roles played by the molecules participating in the adsorption process occurs when all of the hydrogen atoms covalently bonded to the center of unsaturation are replaced by alkyl substituents. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2611–2633, 1999     

Water-soluble copolymers. XII. Copolymers of acrylamide with sodium-3-acrylamido-3-methylbutanoate: Synthesis and characterization

The copolymerization of acrylamide (AM) with sodium-3-acrylamido-3-methylbutanoate (NaAMB) has been studied. The value of r₁r₂ has been determined to be 0.56 for the AM–NaAMB pair. The molecular weights of the copolymers were relatively unaffected by monomer feed ratios. The copolymer microstructures, including run numbers and sequence distributions, were calculated from the reactivity ratios. The solution properties of the AM–NaAMB copolymers, as well as the NaAMB homopolymer, will be reported in a subsequent paper.     

High-molecular-weight hydrolyzed polyacrylamides. II. Potentiometric titrations

Potentiometric titrations in water of high-molecular-weight partly hydrolyzed polyacrylamides were analyzed by the Lifson—Katchalsky rodlike model. A fair concordance was found between theory and experimental curves with pK₀ of acid functions of about 4.75 when 0 < τ < 0.49. Two methods were derived to calculate the parameter n of the extended Henderson-Hasselbach equation by using a series expansion of pK_a vs. α, not yet reported in the literature. A new equation for n was established and comparison between two sets of values of n, obtained by using the theoretical ΔpK curves and series expansion is discussed.     

High-resolution 13C NMR studies of solid 1,4-bis(n-butylamino)anthraquinone

High-resolution ¹³C NMR spectra of solid 1,4-bis(n-butylamino)anthraquinone are presented. In spectra measured at 22.6 MHz the effects of two short-range and two long-range residual (¹³C, ¹⁴N) dipolar couplings have been observed. Only the short-range effects are observable in the 50.3 MHz spectra. These typical asymmetric doublets allow the determination of the ¹⁴N nuclear quadrupole coupling constant (χ=e²Qq/h=?3.0 MHz), the asymmetry parameter (η=0.3) and the orientation of the electric field gradient tensor of the ¹⁴N in the molecular framework.     

Synthetic thermally reversible gel systems. II

The homopolymer and many of the copolymers of N-acrylylglycinamide yield thermally reversible gels in water. These systems are uniquely suitable for studying synthetic photographic gelatin substitutes and for understanding the mechanism of the gelation process. Polymerization of N-acrylylglycinamide has been studied under a variety of conditions. The homopolymer is aggregated in dilute aqueous solution and probably molecularly dispersed in 2M thiocyanate solution. At concentrations of several per cent, in water, thermally reversible gels are formed whose melting points rise with increasing concentration and increasing molecular weight. The heat of gelation crosslinking has been calculated to be ?8.8 kcal./mole of crosslinks. Introduction of small amounts of carboxyl groups into the polymer raises the melting points of the aqueous gels. The effect of various organic and inorganic reagents on gelation is presented. The ability to prepare copolymers which can be flocculated has been demonstrated as well as the usefulness of the monomer in certain types of photoresist systems. Copolymerization with acrylic acid and β-aminoethyl vinyl ether has been studied, and the r₁ and r₂ values for these systems have been calculated as well as Q and e values for N-acrylylglycinamide.