Gel Permeation Chromatography Data Research Articles

Determination of Mark–Houwink constants for polystyrene and polyacrylonitrile terpolymers

AbstractMark–Houwink constants of polystyrene and polyacrylonitrile terpolymers containing acrylonitrile, methyl acrylate, and styrene sulfonic acid or methallyl sulfonic acid as the third comonomer have been calculated from gel permeation chromatography (GPC) and viscosity data. The data have been used to determine molecular weights of polyacrylonitrile terpolymers.

Living carbocationic polymerization of isobutylene by tert‐amyl alcohol/BCl3/1‐methyl‐2‐pyrrolidinone initiating system

Abstract1‐Methyl‐2‐pyrrolidinone has been investigated, for the first time, as an efficient electronpair donor in conjunction with tert‐amyl alcohol and BCl3 in CH2Cl2 diluent at −40°C for the living polymerization of isobutylene. The use of this new monofunctional initiator ‐trans fer (minifer) system has led to the synthesis of low molecular weight, living (near‐monodisperse) polyisobutylenes carrying “ethyl” head group and “tert‐chloro” end group (asymmetric telechelic polyisobutylenes). The nature of these groups was confirmed by 1H‐NMR spectroscopy. The living nature of the α‐ethyl‐ω‐(tert‐chloro)polyisobutylenes has been demonstrated by a linear plot, passing through the origin, of number‐average molecular weight (M̄n) vs. the amount of polymer formed (Wp) and a horizontal N (number of polyisobutylene molecules) vs. Wp plot. These results are further substantiated by gel permeation chromatography data of these polymers, and the molecular weight distributions of these polymers are narrow (low M̄w/M̄n = 1.1–1.2). The initiating efficiencies (Ieff) are close to 100% with this system. Dehydrochlorination of the prepolymer has yielded an isopropylidene (exo‐olefin) end group. Structure of the end group in the resulting polymer, α‐ethyl‐ω‐(isopropenyl)polyisobutylene, was confirmed by FTIR spectroscopy.

Determination of molecular weights and Mark–Houwink constants for soluble electronically conducting polymers

AbstractIntrinsic viscosities and gel permeation chromatography data were used to evaluate the Mark–Houwink constants of the soluble electronically conducting polymer, poly(3‐hexylthiophene) (P3HT):K and a are 2.28 × 10‐3 cm3/g and 0.96, respectively, in tetrahydrofuran (THF) at 25°C. Mark–Houwink constants were used to calibrate gel permeation chromatography (GPC) columns for P3HT. Number‐average molecular weights of P3HT determined with modified calibration curves agreed well with those determined by an absolute method, embulliometry. Molecular weights estimated using unmodified polystyrene calibration procedures were significantly larger than true values.

Effect of phosphoric acid on the polycondensation of ε‐caprolactone with δ‐valerolactone and biodegradation of their copolyesters

AbstractCopolycondensation of ε‐caprolactone (CL) and δ‐valerolactone (VL) was performed in the presence and absence of phosphoric acid, in order to clarify the competition between the ring‐opening reaction of lactones and the polycondensation of linear compounds produced by this reaction. The gel permeation chromatography data showed that the monomer peaks remained in the system even after 7 h from start of the reaction when polymerized in the absence of phosphoric acid and, on the contrary, in the presence of phosphoric acid the peaks disappear perfectly within 1 h. The weight‐average molecular weights (M̄w) of poly(CL‐co‐VL), obtained by copolycondensation with and without phosphoric acid at 200°C for 1 h, were approximately 540 and 8900, suggesting that phosphoric acid markedly accelerates not only the rate of ring‐opening but also the rate of copolycondensation. On the other hand, the biodegradation of the copolyesters obtained is characterized by the action of a lipase‐type enzyme, showing a typical parabolic‐type degradation pattern.

Hyaluronidase Inhibitor in the Fruit of Citrus reticulata BLANCO.

Fifty percent of ethanolic extracts from the immature fruits of Citrus reticulata BLANCO, C. tamurana hort. ex TANAKA, C. natsudaidai HAYATA and C. unshiu MARKOVICH showed a significant inhibitory effect on the activation of inactive hyaluronidase induced by compound 48/80. This effect decreased with the maturation of the fruit in all cases. Among the citrus fruits tested, the extract from the immature C. reticulata BLANCO showed the strongest inhibitory effect. The data of gel permeation chromatography and gas chromatography-mass spectrometry showed the hyaluronidase inhibitor in the fruit to be a pectin with a molecular weight of 1.1×105. The content of D-galacturonic acid in the pectin was determined to be 58% using the carbazole method. The pectin showed almost the same inhibitory effect (IC50 : 91 μg/ml) as a commercial pectin from oranges or a current anti-allergic agent, disodium cromoglycate. Hyaluronidase has been suggested to be one of the target enzymes controlling the degranulation of mast cells, and the inhibitory effect on the activation of inactive hyaluronidase has been reported by Kakegawa et al. (Chem. Pharm. Bull. 33 [1985]) to be an index of anti-allergic activity. Therefore, it is expected that the pectin in C. reticulata BLANCO might possess anti-allergic potential.

Concerning the ability of oligooxyquinoline to accumulate reversibly bound oxygen

A study was performed to find and then to optimize the conditions under which alkaline solutions of H2O2 convert 8-oxyquinoline into an oligomeric oxide. According to infra-red and ultra-violet spectroscopy and gel permeation chromatography data, the oligomer consists mostly of oxyquinolineN-oxide repeat units. A kinetic study of the decomposition of this oligomeric oxide under the action of sulphuric acid in the temperature range 313–343 K showed that up to 6.8 litres of free oxygen were liberated per 100 g of the oligomer. The first-order rate constant at 333 K and activation energy for decomposition were6.05 × 10−4s−1 and 99.2 kJ mol−1 respectively.

Solution properties and characterization of polyisoprenes at a lower critical solution temperature (LCST)

This paper reports two investigations on polyisoprene. One consists of obtaining the molecular weight distribution (MWD) of cis-polyisoprene (PIP) standards by a new method using the turbidity at a lower critical solution temperature (LCST). Advantage is taken for this analysis of the fact that the MW dependence of the critical temperature is greater for systems with a narrow solubility gap, i.e. for systems whose LCST and upper critical solution temperature (UCST) are not too far apart. Typically, in n-pentane, a narrow MW standard phase-separates over 25 K. When the solution is heated by temperature increments of 2 K, 15 fractions can be identified, without physical separation. The relative amount of each phase is analysed by turbidity and the average MW of the phases by the temperature at which they phase separate. The MWs recalculated with two constants for the standards are in excellent agreement with gel permeation chromatography (g.p.c.) data. Possible effects leading to a higher polydispersity found by the LCST are discussed. Application to rubber analysis is feasible. The second investigation consists of reporting and analysing the temperatures of phase separation of medium MWD cis- and trans-PIP samples in a series of linear and branched alkanes. The occurrence of correlations of molecular orientations (CMO) in the melt, similar to those found from thermodynamic analysis of PE solutions, was considered. Trans-PIP has a LCST about 25 K lower than cis-PIP in alkanes. Linear solvents are better solvents than branched ones. The low LCSTs (100°C in n-pentane) support CMO or order in polyisoprene melt or concentrated solutions.

Molecular weight distribution in continuous stirred tank vinyl acetate emulsion polymerization

AbstractEmulsion polymerization typically produces polymers of high molecular weight with broad distributions of molecular size. Many models have been proposed that use either a Flory type distribution, resulting in a polydispersity of two, or a distribution function to represent the breadth of the distribution. In this work, a model for the distribution of molecular weights is derived as a approximation from a detailed molecular weight model that was previously developed. The model is found to approximate the distribution of molecular weights well for several emulsifier concentrations is continuous stirred tank emulsion polymerization of vinyl acetate. An analysis is also conducted of the transformation of gel permeation chromatography data to weight and number fractional distributions of the molecular sizes.

Determination of bimodal molar mass distribution functions of polystyrene by photon correlation spectroscopy: numerical simulations and experimental realization in comparison with gel permeation chromatography data

Determination of bimodal molar mass distribution functions of polystyrene by photon correlation spectroscopy: numerical simulations and experimental realization in comparison with gel permeation chromatography data

Water-dispersible graft copolymer mixtures prepared by electron irradiation. I. Polymerization behavior

Highly viscous systems made up of 70 wt% epoxy resin dissolved in 30 wt% monomer mixtures of acrylic acid and styrene were irradiated with 1.5 MeV electrons to initiate graft copolymerization. The temperature measurement of the systems reveals that the polymerization reaction takes place both during and after the electron-beam exposure of about 5-sec duration. The reaction lasts about 50 sec for a low beam current of 0.6 mA, while for a high beam current of 6.0 mA it lasts merely about 20 sec. The gel permeation chromatography (GPC) measurement of obtained products demonstrates that the molecular weight distribution of ungrafted copolymer of acrylic acid and styrene becomes strikingly broader as the beam current is lowered. The GPC data suggest that the fraction of epoxy resin having a grafted branch increases with an increase in the beam current. All of these results are interpreted in terms of the mobility and the concentration of reactive species such as polymer radicals and low molecular weight free radicals.

Properties of positive resists. I. irradiation-induced degradation and sensitivity of certain methyl methacrylate copolymers

Poly(methyl methacrylate), poly(methyl methacrylate-co-2-hydroxyethyl methacrylate), poly(methyl methacrylate-co-itaconic acid), poly(methyl methacrylate-co-maleic anhydride), poly(methacrylic acid-co-itaconic acid), poly(methacrylic acid-co-maleic anhydride), and poly(itaconic acid) were prepared by copolymerization of the appropriate amounts of the two monomers at 50°C for 24–40 h using benzoyl peroxide as initiator. Selected samples were γ-irradiated with a total dose ranging from 2 to 12 Mrad. The unexposed and degraded polymers were dissolved in tetrahydrofuran and their molecular weight distribution was determined by gel permeation chromatography. It was found that Mn decreased drastically with increasing irradiation dose. The presence of various functional groups in both unexposed and irradiated samples was confirmed by infrared spectroscopy. The copolymer thermodynamic compatibility with various solvents was evaluated on the basis of their fractional solubility parameters. The Gs values of these copolymers were determined using the gel permeation chromatography data. It was established that, among those studied, poly(methyl methacrylate-co-maleic anhydride) is the best material for positive resist application based on a Gs value of 8 9 scissions per 100eV.

Empirical molecular weight distribution functions as determined from gel permeation chromatography data

AbstractTwo‐ and three‐parameter functions commonly used for the description of the molecular weight distribution of polymers were determined from gel permeation chromatography data for 80 water‐soluble samples of polymers derived from glutamic acid. Two methods were applied: the moment method in which two or three different molecular weight averages are used, and a least squares adjustment method using the whole chromatogram. Convergence difficulties observed in the past were overcome, and a fully automated computer procedure was developed. The moment method, although virtually the only one still in use, often gives inexact results: sometimes the type of two‐parameter distribution is wrongly assigned, or the description of experimental data cannot be improved by adding yet another parameter. On the other hand, in all cases under study the least squares method gave a function which describes the real distribution within the limits of experimental error. Although the majority of samples could be described by employing one of the common two‐parameter functions, the more general three‐parameter function, encompassing all two‐parameter ones as special cases, has the advantage of wider applicability. It is shown that the standard gel permeation chromatography data often cannot provide reliable values of higher molecular weight moment averages, including M̄z. Hence, it may be inferred that in the description of the experimental molecular weight distribution curves the least squares method should be preferred over the moment method.

Determination of Mark–Houwink–Sakurada Constants for Measurements of the Molecular Weights by Gel Permeation Chromatography I. On the Generalization of Mathematical Procedure

Fourteen equations in terms of molecular weights and intrinsic viscosity are shown to determine Mark–Houwink–Sakurada (MHS) constants on the basis of gel permeation chromatography (GPC), six equations being for determination from one sample, four from two samples, and four by the method of least squares. These equations are examined, using the data obtained for poly(methyl methacrylate). It is pointed out that the determination of MHS constants from one sample is very sensitive to the measured condition of GPC, and thus we should get good GPC data. Using two samples, the reasonable MHS constants are obtained when the weight-and viscosity-average molecular weights are known. Using more than two samples, the MHS constants are determined by the method of least squares. It is shown that the MHS equation obtained previously under a given condition is transferred to a MHS equation under another condition by GPC where the viscosity-average molecular weights calculated by the former equation are used. Further, using the GPC data obtained under good conditions, good MHS constants can be determined when the number-and weight-average molecular weights are known.

Determination of the Mark-Houwink constants by gel permeation chromatography with correction for longitudinal spreading

The determination of the Mark-Houwink constants using gel permeation chromatography data, based on a known universal calibration dependence and the recorded chromatograms of one or several characterized polydisperse polymer samples, has been modifies by including correction factors for the longitudinal spreading. Verification by means of artificial, computer generated chromatograms shows that the new procedure considerably raises the accuracy and reliability of the results obtained.

Direct estimation of the true Mark-Houwink-Sakurada parameters from gel permeation chromatography, intrinsic viscosity and one average of molecular weight

A method is described for the simultaneous determination of the true constants in the Mark-Houwink viscosity equation and the absolute calibration of gel permeation chromatography data. In this method, polydisperse samples can be used. The experimental data required on each sample are its gel permeation chromatogram, its intrinsic viscosity and one average of molecular weight, M ̄ w or M ̄ n . The method does not require any calibration curve for another polymer (e.g. polystyrene monodisperse standards). The method is applied to the system poly( N-vinyl-3,6-dibromocarbazole) in tetrahydrofuran at 25°C. The procedure may be especially useful in those cases in which, due to the existence of secondary exclusion mechanisms resulting from polymer-stationary phase or polymer-solvent interactions, the hydrodynamic volume universal calibration concept is not valid.

GPC characterization for assessing compatibility problems with heavy fuel oils

Precipitation of solids is one of the major problems associated with the shipping and handling of heavy residual oils especially No. 6 heating oil. ASTM specifications which currently include viscosity, flash point and pouring point are not adequate to predict the handling problems. The residual oils are becoming more complex in composition due to modern refinery techniques for cracking the heavier residues into distillable fractions. In this study, several heating oil samples, including a sample which partially solidified during transport, were analyzed using various techniques including separation by gel permeation chromatography (GPC), vacuum distillation, separation of petroleum asphaltenes by ASTM method, elemental analysis and proton and 13C NMR spectroscopy. The distillable species in the fraction separated by GPC were characterized by high resolution gas chromatography—mass spectroscopy (GC—MS). The study showed that the GPC can be used as a reliable technique for the analysis of heavy residual oils. The GPC separation of No. 6 heating oil gave three fractions enriched with chemically distinct species. The first fraction was composed of heavy molecular species generally known as asphaltenes. The second fraction was mostly straight chain paraffins. The third fraction was composed of low molecular weight aromatics. Although occasional verification of GPC data by GC—MS and by NMR spectroscopy is desirable, the GPC alone is an efficient analytical tool for evaluating the composition as well as predicting the handling problems associated with shipping and storage of various residual oils.

Application of Gel Permeation Chromatography for Investigation of 9-(2, 3-Epoxypropyl)-Carbazole Oligomers

Abstract Gel permeation chromatography on dextran gels “Sephadex LH-2O” and “Sepnadex LH-60” in the solution of dimethyl formamide was used for the estimation of molecular weight and molecular weight distribution of 9-C2, 3-epoxypropyl)carbazole oligomers and for the investigation of the process of their obtaining as well. The simple numerical method of the instrumental dispersion correction as well as the principle of “the differential chromatograms” was used to interpret the gel permeation chromatography data. The method used permits to separate 9-(2, 3-epoxypropyl)carbazole oligomers within the range of molecular weights 150–15000.

Gel permeation chromatographic analyses of resole phenolic resins

AbstractTetrahydrofuran solutions of resole polymers were analyzed by gel permeation chromatography (GPC) on crosslinked polystyrene gel packings. The best separation was obtained with low solvent flow rates in low porosity columns. Irregular elution volumes were observed, but the effects of this erratic behavior can be eliminated by referencing retention times to that of a marker compound such as benzene or phenol. A calibration and data analysis method are presented which utilizes hydrodynamic volumes. Phenolic polymers vary in shape and ability to form hydrogen bonds with solvent; hence their molecular weights cannot be estimated from GPC data. Separation of the constituent species of resole samples is shown to be incomplete, because of aggregation between the various phenol derivatives. Particular peaks in the GPC chromatogram could generally not be assigned to individual species. Despite these limitations, GPC is a useful tool for charcterizing phenolics, and several applications are reviewed here.

A Note on the prediction of polyethylene melt rheological properties from molecular weight distribution data obtained by gel permeation chromatography

AbstractIn the present study, a modification of the method previously presented by the authors for predicting rheological properties of linear polyethylene melts from gel permeation chromatography (GPC) data is presented. The modification involves independent values of the zero shear viscosities for melts rather than generating these values internally. The comparison between the experimental zero shear viscosity values and those calculated from GPC data is shown to be very good.

Plasma etching durability of poly(methyl methacrylate)

AbstractThe decomposition of poly(methyl methacrylate) (PMMA), as a positive resist, in CF4/O2 plasma etching has been studied in the thin film state in order to clarify the factors influencing the dry etching durability of resists. It becomes clear that the major PMMA decomposition in CF4/O2 plasma etching proceeds by the mechanism of random chain scission because very small kinetic chain lengths are estimated from the gel permeation chromatography data. The Arrhenius plots for the plasma etching rate of PMMA bend above about the glass transition temperature (Tg), where rapid increase of the etching rate and remarkable pattern deformation are observed. Activation energy of the PMMA etching rate which is changed by oxygen concentration and rf power indicates various values from 3.1 to 6.5 kcal/mol below about Tg. The result of molecular weight variation in the cross section of the film suggests that the active species permeate into the film with fairly large speed and the PMMA decomposition occurs not only at the film surface but also at deep layer of the film.