Thermodynamic and hydrodynamic properties of dilute solutions of cyclic and linear polystyrenes

Abstract

The thermodynamic and hydrodynamic properties of cyclic and linear polystyrenes, ranging from 10000 to 180 OOO molecular weight, in dilute solutions of cyclohexane have been measured by small-angle neutron scattering (SANS) and dynamic light scattering. The diffusion coefficient D(c) was measured at 6A2=0 as a function of concentration c. The hydrodynamic radii were determined and found to be slightly smaller for cyclic than for linear macromolecules. The slope kD, defined by D(c) = D(O)(l + kDC), was found to be negative and was, within experimental error, independent of molecular architecture. The molecular weight dependence of the radius of gyration, the hydrodynamic radius, and kD is discussed.

Cyclic polymers: Synthetic strategies and physical properties

“…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.…”

The hydrodynamic and conformational properties of denatured proteins in dilute solutions

“…Two studies on ring-shaped polymers prepared by the anionic polymerization of styrene, followed by ring closure give comparable results. [11][12][13] Thus, for linear polystyrene, the experimental K % K 1 is constant for 10 4 < M < 10 6 (K % 2.6) under Flory theta conditions, and in a good solvent (toluene) it decreases from this value as K ! M À0.04 with increasing M, reflecting the differing effects of intramolecular excluded volume on [g] and R 2 G R H .…”

“…[11][12][13] solution, 23 and a constant value of (R G /N 1/2 ) RIS calculated for the rotational-isomeric-state model in the limit of large N. 24 It may be seen that the experimental values of R G /N 1/2 are about equal to H0.7(R G /N 1/2 ) STAT . Thus, if (R G /N 1/2 ) STAT is presumed to be an accurate measure of R G /N 1/2 for the chain without any intramolecular association producing ring structures, g ¼ R 2 G /(R 2 G ) LIN % 0.7, larger than the value g ¼ 1/2 expected for a pure ring-shaped polymer.…”

Synthesis and characterization of macrocyclic poly(.-methylstyrene)

“…The synthesis and properties of macrocyclic polymers, macrocyclic polystyrene (PS) in particular, has been a topic of increased interest in recent years [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Thus the synthesis of macrocyclic PS by cyclization of hetero-bifunctional end functionalized linear precursors has been reported [10][11][12][13][14].…”

“…Most well defined macrocyclic vinyl polymers have been synthesized via coupling of two-ended living polymer dianion precursors at low anion concentrations with difunctional electrophiles at ambient temperatures [1][2][3][4][5][6][7][8][9][10]. Although the anionic polymerization/cyclization method is rapid and synthetically convenient, one of the main difficulties with this method is the presence of highly reactive dianion polymer precursors that, at least at ambient temperatures, may be partially protonated or otherwise terminated.…”