Diffusion in microstructured block copolymer melts

Lodge, Timothy P.; Hamersky, Mark W.; Milhaupt, Jodi M.; Kannan, Rangaramanujam M.; Dalvi, M. C.; Eastman, C. E.

doi:10.1002/masy.19971210119

Cited by 30 publications

(63 citation statements)

References 22 publications

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“…Within the experimental time window of 300 ms, no exchange of free chains and of those bound to micelles was observed, because of enthalpic and entropic barriers and because the friction in the polystyrene spheres is relatively high. Lodge et al studied an asymmetric poly(ethylene propylene)-poly(ethylethylene) (PEP-PEE) diblock copolymer sample showing an order-order transition (OOT) from the cylindrical to the spherical state [20]. Using forced Rayleigh scattering on a shear oriented sample, these authors did not find any discontinuity in the diffusion coefficient at the OOT.…”

Section: Introductionmentioning

confidence: 96%

“…The micelles were not found to move in the time window of the simulation [18]. We are only aware of three experimental studies dealing with the dynamics in micelle-forming diblock copolymer melts [19][20][21]. Fleischer et al used pulsed field gradient NMR to study the self-diffusion of a strongly asymmetric polystyrene-polyisoprene diblock copolymer forming the body-centered cubic structure [19].…”

Section: Introductionmentioning

confidence: 97%

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The bulk dynamics of a compositionally asymmetric diblock copolymer studied using dynamic light scattering

et al. 2000

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We have studied the bulk dynamics of a compositionally asymmetric poly(ethylene propylene)-poly(dimethylsiloxane) (PEP-PDMS) diblock copolymer in a large temperature range both in the ordered and in the disordered state. The volume fraction of the PEP block is 0.22. Apart from the disordered state, the sample shows three ordered morphologies. Using dynamic light scattering, we have investigated the dynamics in all four phases and combined these results with those obtained using pulsed field gradient NMR. In the disordered state, we find-apart from the slow cluster mode-the heterogeneity mode related to the self-diffusion of single chains. The relaxation time τ of this mode, reduced by temperature and the zero-shear viscosity η, log(τ T /η), increases with temperature. In the cubic phase right below the ODT temperature, we observe two diffusive processes, and we attribute the faster one to the mutual diffusion of micelles and block copolymers not bound to micelles ("free chains") through the PDMS matrix. The slower mode may either be due to the mutual diffusion of free chains and chains bound to PEP micelles or to the cooperative diffusion of micellar aggregates. In the non-cubic ordered state at intermediate temperatures, an additional weak diffusive mode is observed. The low-temperature ordered state is body-centered cubic, and here, only the mutual diffusion of micelles and free chains lies in our experimental time window.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 97%

The bulk dynamics of a compositionally asymmetric diblock copolymer studied using dynamic light scattering

et al. 2000

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“…The dynamics of the chain end-to-end vector were mainly studied by dielectric spectroscopy 5 and the translational dynamics by forced Rayleigh scattering ͑FRS͒. 6 Lodge and co-workers have investigated the self-and tracer diffusion in lamellar microphase-separated symmetric diblock copolymers, also in the macroscopically oriented state. 6 The case of nonentangled block copolymers was found to be anisotropic: whereas the diffusion along the lamellae is not retarded, the diffusion perpendicular to the lamellae is strongly slowed down as a consequence of the thermodynamic repulsion between the two blocks.…”

Section: Introductionmentioning

confidence: 99%

“…6 Lodge and co-workers have investigated the self-and tracer diffusion in lamellar microphase-separated symmetric diblock copolymers, also in the macroscopically oriented state. 6 The case of nonentangled block copolymers was found to be anisotropic: whereas the diffusion along the lamellae is not retarded, the diffusion perpendicular to the lamellae is strongly slowed down as a consequence of the thermodynamic repulsion between the two blocks. This was also confirmed in a recent study of the self-diffusion in a symmetric poly͑ethylenepropylene͒-polydimethylsiloxane ͑PEP-PDMS͒ diblock copolymer by means of pulsed field gradient ͑PFG͒ NMR.…”

Section: Introductionmentioning

confidence: 99%

Self-diffusion of an asymmetric diblock copolymer above and below the order-to-disorder transition temperature

Fleischer

Rittig

Kärger

et al. 1999

The Journal of Chemical Physics

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Microphase separation in poly(isoprene-b-ethylene oxide) diblock copolymer melts. I. Phase state and kinetics of the order-to-order transitionsThe self-diffusivity of an asymmetric poly͑ethylenepropylene͒-poly͑dimethylsiloxane͒ diblock copolymer ͑PEP-PDMS͒ was investigated using pulsed field gradient NMR both in the ordered and the disordered state. In a temperature range below the order-to-disorder transition temperature, the diblock copolymer forms micelles which order in a simple cubic structure, and at lower temperatures, a noncubic structure is formed. We have found a broad distribution of self-diffusivities. The distribution width increases with decreasing temperature. The self-diffusivity as well as its distribution width changes only slightly at the order-to-disorder transition. In contrast to self-diffusion in symmetric diblock copolymers where single chains diffuse independently, our results are interpreted as a collective diffusion of chains confined to micelles which further cluster to larger aggregates. This behavior cannot be described by existing models of chain dynamics in the melt. The disordered state is characterized by a large temperature range above the order-to-disorder transition where concentration fluctuations dominate. This is revealed in the temperature dependence of the self-diffusivity and its distribution width, in the viscosity and in the inverse intensity of the first-order Bragg reflection in small angle neutron scattering ͑SANS͒.

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“…Specifically, in the direction perpendicular to the A-B interface, the diffusion constant scales with e -αχN . 21,22 These two competing factors would likely lead one to the expectation that χ and χN may have an optimal value at some intermediate value between the extremes of very weak incompatibility between the two blocks coupled with very high mobility, and very high incompatibility between the two blocks coupled with very low mobility; some intermediate χ and χN value might be best. This work will use a coarse-grained model to study the rates, pathways, and dependencies of healing a common defect to give insight into the fundamental processes that control defect healing and give guidance on optimal process conditions for BCP-DSA.…”

Section: Introductionmentioning

confidence: 96%

Coarse-grained molecular dynamics modeling of the kinetics of lamellar BCP defect annealing

Peters

Lawson

Nation

et al. 2015

Alternative Lithographic Technologies VII

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Directed self-assembly of block copolymers (BCPs) is a process that has received great interest in the field of nanomanufacturing in the past decade, and great strides towards forming high quality aligned patterns have been made. But state of the art methods still yield defectivities orders of magnitude higher than is necessary in semi-conductor fabrication even though free energy calculations suggest that equilibrium defectivities are much lower than is necessary for economic semi-conductor fabrication. This disparity suggests that the main problem may lie in the kinetics of defect removal. This work uses a coarse-grained model to study the rates, pathways, and dependencies of healing a common defect to give insight into the fundamental processes that control defect healing and give guidance on optimal process conditions for BCP-DSA. It is found that infinitely thick films yield an exponential drop in defect heal rate above χN ~ 30 . Below χN ~ 30, the rate of transport was similar to the rate at which the transition state was reached so that the overall rate changed only slightly. The energy barrier in periodic simulations increased with 0.31 χN on average. Thin film simulations show no change in rate associated with the energy barrier below χN ~ 50, and then show an increase in energy barrier scaling with 0.16χN. Thin film simulations always begin to heal at either the free interface or the BCPunderlayer interface where the increased A-B contact area associated with the transition state will be minimized, while the infinitely thick films must start healing in the bulk where the A-B contact area is increased. It is also found that cooperative chain movement is required for the defect to start healing.

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Diffusion in microstructured block copolymer melts

Cited by 30 publications

References 22 publications

The bulk dynamics of a compositionally asymmetric diblock copolymer studied using dynamic light scattering

The bulk dynamics of a compositionally asymmetric diblock copolymer studied using dynamic light scattering

Self-diffusion of an asymmetric diblock copolymer above and below the order-to-disorder transition temperature

Coarse-grained molecular dynamics modeling of the kinetics of lamellar BCP defect annealing

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