Conformational Properties of Ring AB Diblock Copolymers

Vlahos, Costas; Hadjichristidis, Nikos; Kosmas, Marios K.; Rubio, Ana M.; Freire, Juan J.

doi:10.1021/ma00124a021

Cited by 11 publications

(9 citation statements)

References 9 publications

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“…It is worth noting that in this study the adsorption amount for cyclic PEG has a higher dependence on molecular weight than linear PEG (Table ), which is contradictory to previous studies. − This might be due to the method used to determine the adsorption amount. Since SANS is less sensitive to tails in adsorbed layer, it may underestimate the adsorption amount of linear PEG, especially with increasing tails fraction at higher molecular weight.…”

Section: Discussioncontrasting

confidence: 85%

“…In the case of cyclic polymer adsorption, the situation could be very different because no tails can be formed from cyclic polymers. It was shown that cyclic polymers had higher adsorption amounts than their linear analogues upon solid/liquid interfaces, at low molecular weights, in agreement with theoretic predictions. − However, the above studies on cyclic polymer adsorption mainly concern the polymer molecular weight and polymer interface or polymer–solvent interaction potentials. The effect of surface curvature has been largely overlooked.…”

Section: Introductionsupporting

confidence: 55%

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Small-Angle Neutron Scattering Study of Cyclic Poly(ethylene glycol) Adsorption on Colloidal Particles

2014

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The adsorptions of cyclic PEG and linear PEG on colloidal silica particles were compared. Their adsorption volume fraction profiles were generated through model fitting of small-angle neutron scattering data from the adsorbed polymer layers. The two important parameters to describe adsorbed polymer layers were discussed in detail. It was found that the adsorption amounts of cyclic PEGs increased with molecular weight but were generally higher than their linear counterparts. However, the root-mean-square layer thickness, δ(rms), of adsorbed cyclic PEGs was found to decrease with molecular weight, opposing adsorbed linear PEGs and the theoretic prediction based on SF model. This disagreement was ascribed to the topological restriction of cyclic polymer at low molecular weight. An illustrated structural evolution with molecular weight for adsorbed polymer at interface was tentatively proposed based on the observations of this study.

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Section: Discussioncontrasting

confidence: 85%

Section: Introductionsupporting

confidence: 55%

Small-Angle Neutron Scattering Study of Cyclic Poly(ethylene glycol) Adsorption on Colloidal Particles

2014

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“…For R-CP there are two connections between the blocks in the same chain and, therefore, it is expected that its properties should differ from those of L-CP. Earlier studies regarding microphase separation, conformational properties, phase behavior, − and rheology of pure R-CP melts focus on the systems in bulk. Also, to our best knowledge, the behavior of L-CP and R-CP blends in thin-film geometry has received little attention.…”

Section: Introductionmentioning

confidence: 99%

Ring and Linear Copolymer Blends under Confinement

Shagolsem

2018

J. Phys. Chem. B

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The behavior of dense mixtures of two topologically different diblock-copolymer (CP) chains, viz., linear(L)-CP and ring(R)-CP of same molecular weight which forms lamellae is studied under confinement by two non-selective substrates. The effect of varying interaction strength between L-CP and R-CP, from purely repulsive (demixed state) to weakly attractive (mixed state), on the morphology, domain size, chain conformations and distribution of chains in the film are investigated. In the demixed state, collective structure factor S(q) shows a split of the predominant peak indicating the presence of two dominant length scales. While there is only one predominant peak in the mixed state, and hence a lamellar structure with single domain size. We show that the peak position q * of S(q) can be varied with the L/R interaction strength and thus allow one to control domain size by tuning L/R interaction strength without altering the chain size. We further characterize the chain size and illustrate that this domain size variation is a consequence of the variation in the size of L-CPs. Furthermore, results on the average instantaneous shape of R/L-CP reveal that their shapes are very different both in bulk and near the substrate, and R-CP assumes an oblate shape near the substrate. This shape/size difference leads to the segregation of R-CPs near the polymer-substrate interface and hence a relatively higher density of R-CPs at the interface.

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“…1−5 In dilute solution for the macroscopic state of common Θ solvent the dimensions of ring copolymers are 0.58 times smaller than the respective dimensions of their linear precursors. 2 Experiments 3 of polystyrene-block-polyisoprene (PS 290 -b-PI 110 ) diblock copolymers in heptane (a selective solvent for PI) have shown that the cyclization strongly affects the micellization behavior. In every copolymer concentration up to 20 mg/mLthe linear diblock chains form spherical micelles with diameter of 40 nm with PS core and PI shell.…”

Section: Introductionmentioning

confidence: 99%

“…The absence of end-groups in ring copolymers leads to significantly different physical properties compared to the linear or branched counterparts both in dilute solution and bulk. − In dilute solution for the macroscopic state of common Θ solvent the dimensions of ring copolymers are 0.58 times smaller than the respective dimensions of their linear precursors . Experiments of polystyrene- block -polyisoprene (PS 290 - b -PI 110 ) diblock copolymers in heptane (a selective solvent for PI) have shown that the cyclization strongly affects the micellization behavior.…”

Section: Introductionmentioning

confidence: 99%

Micellization Properties of Θ-Shaped, Figure-Eight-Shaped and Linked Rings Copolymers

et al. 2014

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The micellization behavior of Θ-shaped, figure-eight-shaped, and linked rings copolymers is studied by means of molecular dynamics simulations with Langevin thermostat. The properties of interest were the critical micelle concentration, the mean aggregation number and the shape of the micelle. We found that the Θ-shaped copolymers form micelles with preferential aggregation numbers. The shape of these micelles is spherical with elongated spherical cores. The homo figure-eight-shaped copolymers also form spherical micelles with preferential aggregation numbers and elongated spherical cores. The mikto figure-eight-shaped and the linked rings copolymers form wormlike or superstructured micelles with a wide range of aggregation numbers. Our simulation results on cmc and the micelles mass distribution are compared with existing experimental findings for the homo and mikto figure-eight-shaped copolymers.

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Conformational Properties of Ring AB Diblock Copolymers

Cited by 11 publications

References 9 publications

Small-Angle Neutron Scattering Study of Cyclic Poly(ethylene glycol) Adsorption on Colloidal Particles

Small-Angle Neutron Scattering Study of Cyclic Poly(ethylene glycol) Adsorption on Colloidal Particles

Ring and Linear Copolymer Blends under Confinement

Micellization Properties of Θ-Shaped, Figure-Eight-Shaped and Linked Rings Copolymers

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