Effect of Solvent on Concentration Dependence of Hydrodynamic Volumes and GPC Elution Volumes

Mahabadi, H. K.; Rudin, Alfred

doi:10.1295/polymj.11.123

Cited by 73 publications

(15 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The points for linear and cyclic oligomers define two parallel straight lines, reflecting the more compact conformations of the cyclic oligomers. For molecular weights in the linear range for a GPC column, the elution time t is related to the molecular hydrodynamic volume V h by equation 2 36 ,…”

Section: Resultsmentioning

confidence: 99%

Supramolecular nesting of cyclic polymers

et al. 2015

View full text Add to dashboard Cite

Monodisperse cyclic porphyrin polymers, with diameters of up to 21 nm (750 C-C bonds), have been prepared using Vernier template-directed synthesis. The ratio of the intrinsic viscosities for cyclic and linear topologies is 0.72, indicating that these polymers behave as almost ideal flexible chains in solution. When deposited on gold surfaces, the cyclic polymers display a new mode of two-dimensional supramolecular organisation, combining encapsulation and nesting: one nanoring adopts a near-circular conformation thus allowing a second nanoring to be captured within its perimeter, in a tightly folded conformation. Scanning tunnelling microscopy reveals that nesting occurs in combination with stacking when nanorings are deposited under vacuum, whereas when they are deposited directly from solution under ambient conditions, there is stacking or nesting, but not a combination of both.The tertiary structures of biological macromolecules are achieved through folding, coiling and multiplex formation, driven by the cooperative effect of many weak interactions 1 . Synthetic monodisperse macromolecules with similar cooperative folding behaviour provide a viable approach to the programmed fabrication of 3D nanostructures [2][3][4][5] . Here we show that cyclic porphyrin polymers, with molecular weights of 30-60 kDa, self-assemble into nested structures on a gold surface. These nested assemblies are only observed when the cyclic polymer has 30 or more repeat units, in keeping with the predictions of a simple geometrical model.The importance of non-covalent self-assembly in biology has inspired many studies of supramolecular organisation on surfaces [6][7][8] , generating 2D assemblies with progressively escalating complexity, from early work on simple structures such as clusters 9 and rows 10,11 , to nanoporous arrays 12,13 , host-guest architectures [14][15][16] , hierarchical arrangements 17 , and multicomponent assemblies [17][18][19] . However, cooperative conformational control has proved difficult to achieve, and this remains a significant gulf between artificial and biological systems. One reason for this difference is that biological macromolecules are much more flexible than the component molecules studied in 2D supramolecular assemblies which are small and, with some exceptions 20,21 , are often treated as quasi-rigid building blocks. Here we illustrate how interactions between large flexible molecules can result in biomimetic cooperative conformational organisation.Studies of linear and cyclic butadiyne-linked zinc porphyrin oligomers (structures l-PN THS and c-PN, Fig. 1) have shown that the distance between the centres of the porphyrin units along the chain is a = 1.35 nm 5,22,23 . Thus the contour length of a linear oligomer, or the perimeter of a nanoring, is Na, where N is the number of porphyrin repeat units. Previously we have shown that nanorings adsorbed on Au(111) exhibit flexibility [24][25][26] , and also that they can act as nanoscale traps for other adsorbed species, such as C 60 guest molecules 2...

show abstract

Section: Resultsmentioning

confidence: 99%

Supramolecular nesting of cyclic polymers

et al. 2015

View full text Add to dashboard Cite

show abstract

“…As reported,12,13 the slopes of linear plots of V e vs c 2 strongly depend on the thermodynamic quality of the eluent with respect to the polymer and become higher as the molar mass of the polymer increases, especially for good solvents. As usually found in the literature,11–24 the hydrodynamic volume of the polymer decreases as the injected polymer concentration increases making its V e higher than the one obtained at zero concentration, especially for polymers of high molar mass. Therefore, to avoid concentration effects on elution volumes, all polymeric solute samples should be injected at different concentrations and the elution volumes extrapolated to zero concentration.…”

Section: Resultsmentioning

confidence: 52%

“…In summary, as a main conclusion, and as it has been quantitatively corroborated, there is a clear influence of the preferential solvation effect on the polymer elution behavior in SEC. In the past,11,14–17 the dependence of elution volumes on the polymer concentration injected had been only attributed to conventional hydrodynamic aspects (solvent quality affecting the coil size) although never before had the thermodynamic effects had been taken into account. Similar work on other commercial SEC packings is currently in progress.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, another factor affecting the quantitative evaluation of polymer–packing interactions in SEC, is the concentration effect, i.e., the dependence of the elution volume on the injected polymer concentration, especially for good solvents. This effect has been mainly interpreted on the basis of hydrodynamic factors 11–24. In this paper, the concentration effect has also been correlated with the preferential solvation phenomenon.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

An Analysis of the Concentration Effects on Elution Volumes by Using the Preferential Solvation Parameter in Two SEC Packings

Garcı́a-Lopera

Gómez

Abad

et al. 2002

Macro Chemistry & Physics

View full text Add to dashboard Cite

Size exclusion chromatography (SEC) elution behavior of different solvent/polymer systems has been analyzed from chromatographic, thermodynamic, and hydrodynamic points of view in two organic column packings based on polystyrene/divinylbenzene (PS/DVB) copolymer, μ‐styragel and TSK‐Gel HHR. Although both packings present similar chromatographic properties, some differences arise when eluting the same systems. The values of the adsorption distribution coefficients, Kp, have been correlated with the preferential solvation coefficient, λ (see Figure), for both packings, showing that those systems with lower and negative λ values (denoting higher preferential solvation of the polymer by the gel packing) are those with Kp > 1. In addition, the main goal has been to make use of the λ values to adequately interpret the dependence of the elution volumes on injected polymer concentration. In this regard, the experimental concentration effects have been completely explained by taking into account not only the conventional hydrodynamic factors but also thermodynamic aspects such as the preferential solvation phenomenon.Plot of the preferential solvation coefficient, λ, as a function of the volume fraction of polymer (2), ϕ2, at three hydrodynamic volumes, Vh = 106 (○ •); 107 (□ ▪), and 108 (▵ ▴) mL · mol−1 for the system THF/PBD/PS (μ‐styragel: empty symbols; TSK‐Gel HHR (solid symbols).magnified imagePlot of the preferential solvation coefficient, λ, as a function of the volume fraction of polymer (2), ϕ2, at three hydrodynamic volumes, Vh = 106 (○ •); 107 (□ ▪), and 108 (▵ ▴) mL · mol−1 for the system THF/PBD/PS (μ‐styragel: empty symbols; TSK‐Gel HHR (solid symbols).

show abstract

“…The parameters h, refer to valley-to-peak ratio calculations [eq. (7)], while f and g are used to calculate peak separation [eq. (S)].…”

Section: 000mentioning

confidence: 99%

Comments on methods for evaluating SEC column performance

Grinshpun

Rudin

1987

J. Polym. Sci. A Polym. Chem.

Self Cite

View full text Add to dashboard Cite

The parameter that is used most frequently to summarize SEC column performance is plate number. The number of theoretical plates, N, is defined by N = ( ? ) 'where tR is the peak retention time and o' is the variance. The column plate number is determined experimentally by injecting a low molecular weight material into the apparatus and calculating N according to eq. Plate count has limited use in selecting SEC columns since the experimental solute usually has much smaller size than the polymeric species that are of prime interest in these analyses.Balke' has recently reviewed techniques for assessment of resolution of SEC columns and their use in comparing the fractionation quality of different columns. Of these methods, the most useful appear t o be the resolution, the valley-to-peak ratio, and the peak separation.Resolution, R,, is frequently used in chromatography as a measure of peak overlap. This parameter is defined by eq. (3).where the numerator is the difference between the retention times of neighboring peaks (subscripted 1 and 2) and the denominator is the mean width of the two peaks.This method of determining resolution is simple and quantitative if peak widths are measured by drawing tangents to the curves at half heights, rather than by assuming Gaussian forms?If the peaks are indeed Gaussian then R , can be related to the number of theoretical plates by assuming that the plate number is consistant for neighboring peaks. Then R , = 0.25m( -)(a kHere k is the mean capacity factor for the two peaks, where the capacity factor for peak c, k,, is defined by

show abstract

Effect of Solvent on Concentration Dependence of Hydrodynamic Volumes and GPC Elution Volumes

Cited by 73 publications

References 38 publications

Supramolecular nesting of cyclic polymers

Supramolecular nesting of cyclic polymers

An Analysis of the Concentration Effects on Elution Volumes by Using the Preferential Solvation Parameter in Two SEC Packings

Comments on methods for evaluating SEC column performance

Contact Info

Product

Resources

About