Studies of cyclic and linear poly(dimethyl siloxanes): 3. Neutron scattering measurements of the dimensions of ring and chain polymers

Higgins, J. S.; Dodgson, K.; Semlyen, J.A.

doi:10.1016/0032-3861(79)90164-2

Cited by 137 publications

(92 citation statements)

References 25 publications

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“…Regardless, if synthetic procedures are described in detail or not, numerous publications report on solution properties of cyclic homopolymers frequently including a comparison with their linear counterparts (precursors) having the same molar masses. 10,11,51,52,55,58,60,73,95,[249][250][251][252][253][254][255][256][257][258][259][260][261][262][263][264][265] It was found in agreement with theoretical considerations that the hydrodynamic volume of the cyclic polymers is smaller (or the coil density higher) than that of the corresponding linear polymers. Therefore, solution viscosities of cyclic polymers are lower and their elution volumes or elution times in SEC measurements are higher than those of their linear analogues.…”

Section: Solution Propertiessupporting

confidence: 64%

Cyclic polymers: Synthetic strategies and physical properties

Kricheldorf

2009

J. Polym. Sci. A Polym. Chem.

400

442

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Syntheses of cyclic polymers including cyclic homopolymers, cyclic block copolymers, sun-shaped polymers, and tadpole polymers are discussed on the basis of a differentiation between synthetic methods and synthetic strategies (e.g., polycondensation, ring-ring equilibration, or ring-expansion polymerization). Furthermore, all synthetic methods are classified as kinetically or thermodynamically controlled reactions. Characteristic properties of cyclic polymers such as smaller hydrodynamic volume, lower melt viscosities, and higher thermostabilities are compared to the properties of their linear counterparts. Furthermore, the nanophase separation of cyclic diblock copolymers is discussed.

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Section: Solution Propertiessupporting

confidence: 64%

Cyclic polymers: Synthetic strategies and physical properties

Kricheldorf

2009

J. Polym. Sci. A Polym. Chem.

400

442

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“…Extrapolation of data obtained by exact enumeration to infinite chain-length yielded g = 0.52, [56] those of Monte Carlo results based on short chains (rings) g = 0.53 to g = 0.57 [57 -60] the latter being in good agreement with a result of first order perturbation theory. [61] Experimental investigations [62] of linear and ring-shaped poly(dimethylsiloxane) in good solvent yielded g L 0.53. Based on the present data, g-values in the range 0.550 (N = 32) to 0.537 (N = 8192) are found.…”

Section: Mean Square Dimensionsmentioning

confidence: 99%

Monte Carlo Simulation Studies of the Size and Shape of Ring Polymers

Zifferer¹,

Preusser

2001

Macromol. Theory Simul.

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“…While all experimental studies have dealt with the dilute solution behavior of cyclic molecules [1][2][3][4] theoretical and computational work has been carried out on cyclics, in bulk. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] The general conclusion is that the conformation of rings in the melt differs significantly from that in solution, as a result of topological constraints active in concentrated systems but not in dilute solution.…”

Section: Introductionmentioning

confidence: 99%

On the difference in scattering behavior of cyclic and linear polymers in bulk

Gagliardi

Arrighi

Ferguson

et al. 2005

The Journal of Chemical Physics

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It has been suggested that, due to topological constraints, rings in the melt may assume a more compact shape than Gaussian chains. In this paper, we exploit the availability of narrow fractions of perdeuterated linear and cyclic polydimethylsiloxane ͑PDMS͒ and, through the analysis of the small angle neutron scattering ͑SANS͒ profiles, demonstrate the difference in scattering properties of linear and cyclic PDMS molecules. As expected for Gaussian chains, for the H/D linear PDMS samples, log-log plots of the scattered intensity versus scattering vector Q display a Q ͑−2͒ dependence. However, for H/D cyclic blends, the scaling exponent is higher than 2, as predicted by computer simulations reported in the literature. We show that cyclic molecules in bulk display the characteristic maximum in plots of scattered intensity versus Q ͑−2͒ that is expected on the basis of Monte Carlo calculations and from the Casassa equation ͓E. F. Casassa, J. Polym. Sci. A 3, 605 ͑1965͔͒. It is also shown that, for rings, the Debye equation ͓P. Debye, J. Appl. Phys. 15, 338 ͑1944͔͒ is no longer appropriate to describe the SANS profiles of H/D cyclic blends, at least up to M w Ϸ 10 000. For these samples, the Casassa form factor gives a better representation of the SANS data and we show that this function which was developed for monodisperse cyclics is still adequate to describe our slightly polydisperse samples. Deviations from all above observations are noted for M w Ͼ 11 000 and are attributed to partial contamination of cyclic samples with linear chains. The failure of both the Debye and the Casassa form factors could be due to contamination of the cyclic fractions by linear polymers or to a real conformational change.

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Studies of cyclic and linear poly(dimethyl siloxanes): 3. Neutron scattering measurements of the dimensions of ring and chain polymers

Cited by 137 publications

References 25 publications

Cyclic polymers: Synthetic strategies and physical properties

Cyclic polymers: Synthetic strategies and physical properties

Monte Carlo Simulation Studies of the Size and Shape of Ring Polymers

On the difference in scattering behavior of cyclic and linear polymers in bulk

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