Effects of Substrate Interactions in Liquid Chromatography of Star Homopolymers and Star Block Copolymers

Kosmas, Marios K.; Kokkinos, Ioannis G.; Bokaris, Efthymios P.

doi:10.1021/ma0103268

Cited by 15 publications

(17 citation statements)

References 19 publications

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“…The critical condition is usually defined as the point at which the weak attractive enthalpic interaction effect is exactly compensated by the entropic exclusion effect for a linear homopolymer, and the polymer species elutes near the elution time of the injection solvent, independent of its molecular weight. ,, LCCC has been successfully employed for the characterization of a variety of complex polymer systems such as functionality analysis, polymer blends, block copolymers, – stereoregularity analysis, cyclic polymers, etc. The LCCC retention of branched polymers has been also examined theoretically by several authors. ,– In the theoretical works, an ideal chain model was employed to calculate the partition coefficient of branched polymers in a pore. Theoretical calculations showed that if star-shaped polymers are chemically the same and are at the critical condition, the partition coefficient of the star-shaped polymers is independent of chain architecture.…”

Section: Introductionmentioning

confidence: 99%

Retention Behavior of Star-Shaped Polystyrene near the Chromatographic Critical Condition

Im¹,

Park²,

Kim³

et al. 2008

Macromolecules

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The retention behavior of star-shaped polystyrene (PS) at the liquid chromatographic critical condition of linear PS was investigated. The star-shaped PS samples were prepared by anionic polymerization of styrene and subsequent linking of the polystyryl anions with divinylbenzene. The linking reaction yields a series of star-shaped PS with different number of branches of equal length. Three star-shaped PS samples with different arm molecular weight (MW) were prepared. To investigate the MW (hence the branch number) dependence of the LCCC (liquid chromatography at the critical condition) retention, the two-dimensional liquid chromatography method was usedsfirst separating the polymers with respect to the molecular weight and subsequently separating the effluent by LCCC. Two different pore size columns were used for the LCCC separation to investigate the pore size dependence. The LCCC retention shows a very complex behavior. The retention time of the starshaped PS shows a strong variation with MW (branch number) at the coelution condition of linear PS, and the deviation from the coelution behavior is more serious at a smaller pore sized column. The peculiar LCCC retention behavior was successfully delineated by a lattice Monte Carlo method taking into account the excluded volume and weak attractive interaction of the chain ends.

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Section: Introductionmentioning

confidence: 99%

Retention Behavior of Star-Shaped Polystyrene near the Chromatographic Critical Condition

Im¹,

Park²,

Kim³

et al. 2008

Macromolecules

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“…The differences in CAP for linear and branched chains have also been investigated theoretically and by computer simulations. − The results of theoretical studies based on the Gaussian chain model showed that if the linear and branched polymers are chemically identical, their partition coefficients (LC retention) are essentially the same at the CAP of the linear polymers. − Computer simulation using the lattice-based random walk model also yielded practically the same result. , They showed that, for the random walk case, both linear and branched polymers exhibit CAP behavior at the same interaction energy between the polymer segment and the pore wall (i.e., same T CAP for linear and star-shaped polymers) while the partition coefficient of star-shaped polymers is slightly larger than that of linear polymers ( t E, star > t E, linear ). The small difference was attributed to the chain-end effect, i.e., the absence of the neighboring repeating unit, and t E, star increases as the number of arms increases at the same overall MW.…”

Section: Introductionmentioning

confidence: 99%

Influence of the Chain Architecture and the Presence of End-Groups or Branching Units Chemically Different from Repeating Structural Units on the Critical Adsorption Point in Liquid Chromatography

et al. 2017

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The critical adsorption point (CAP) of linear and star-shaped polymers was investigated by normal phase and reversed phase liquid chromatography (NPLC and RPLC) and computer simulation. Three sets of polystyrenes (PS) differing in chain architecture and chemically distinct groups were prepared: linear PS (sec-butyl and hydrogen end group), 2-arm PS (linear, two sec-butyl end groups and one silyl group in the middle of the chain) and 4-arm star-shaped PS (four sec-butyl end groups and one silyl group in the center of the star). It was found that the column temperature at CAP, T CAP (linear PS) = T CAP (2-arm PS) > T CAP (4-arm PS) in both RPLC and NPLC which can be attributed to the variation in chain architecture. However, the elution times at CAP of three polymers are all different: In NPLC, t E,CAP (linear) > t E,CAP (2-arm PS) > t E,CAP (4-arm PS) while in RPLC, t E,CAP (4-arm PS) > t E,CAP (2-arm PS) > t E,CAP (linear). The variation of t E,CAP can be explained by the contribution of the chemically distinct groups. The computer simulation results are in good agreement with the chromatography experiments results and support the interpretation of experimental data.

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“…That would result in a topology-independent elution under critical conditions for linear and branched polymers. Kosmas et al derived equations for the elution behavior of star polymers and predicted also identical critical elution behavior of linear and star polymers . However, Wang et al , emphasized the importance of the excluded volume interaction which was not taken into account in Guttman’s calculations.…”

Section: Introductionmentioning

confidence: 99%

“…Kosmas et al derived equations for the elution behavior of star polymers and predicted also identical critical elution behavior of linear and star polymers. 22 However, Wang et al 23,24 emphasized the importance of the excluded volume interaction which was not taken into account in Guttman's calculations. Wang pointed out that the excluded volume has a nontrivial effect on polymers eluting at critical conditions.…”

Section: Introductionmentioning

confidence: 99%

Retention Behavior of Linear, Branched, and Hyperbranched Polyesters in Interaction Liquid Chromatography

et al. 2010

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The retention behavior of aromatic polyesters possessing different degrees of branching was studied in gradient liquid adsorption chromatography (gradient chromatography), liquid adsorption chromatography (LAC), and liquid chromatography at the critical conditions (LCCC). The chromatographic experiments revealed that retention of linear and branched polyesters is influenced by the degree of branching as well as the molar mass of the polymer samples in all enthalpy-dominated chromatographic modes such as LAC, LCCC, and gradient chromatography. At critical conditions of the linear polymer, the corresponding branched structures elute in the adsorption mode, indicating a stronger adsorptive interaction between the stationary phase and the branched polymer molecule. In gradient chromatography, polymer samples with higher degrees of branching are retarded longer on the stationary phase. A clear dependence between the degree of branching and the elution volume was found in both chromatographic modes, which clearly demonstrates a pronounced effect of topology on retention behavior. The results suggest the use of gradient chromatography as a first separation step for a two-dimensional characterization method of branched polymers in order to separate by both degree of branching and molar mass.

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Effects of Substrate Interactions in Liquid Chromatography of Star Homopolymers and Star Block Copolymers

Cited by 15 publications

References 19 publications

Retention Behavior of Star-Shaped Polystyrene near the Chromatographic Critical Condition

Retention Behavior of Star-Shaped Polystyrene near the Chromatographic Critical Condition

Influence of the Chain Architecture and the Presence of End-Groups or Branching Units Chemically Different from Repeating Structural Units on the Critical Adsorption Point in Liquid Chromatography

Retention Behavior of Linear, Branched, and Hyperbranched Polyesters in Interaction Liquid Chromatography

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