Dynamics of structure formation at the microphase separation transition in diblock copolymers

Schuler, M.; Stuehn, B.

doi:10.1021/ma00053a017

Cited by 36 publications

(43 citation statements)

References 6 publications

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“…[10][11][12][13][14] The observed nucleation and growth process agrees well to the weak first-order nature of the isotropic-to-lamellar phase transition predicted by Fredrickson and Helfand under consideration of the fluctuation correction to the mean-field theory. [10][11][12][13][14] The observed nucleation and growth process agrees well to the weak first-order nature of the isotropic-to-lamellar phase transition predicted by Fredrickson and Helfand under consideration of the fluctuation correction to the mean-field theory.…”

Section: Introductionsupporting

confidence: 83%

“…It generally exhibits three regimes. [10][11][12][13][14] In thermally activated nucleation Morphology evolution reveals that the lamellar domains grow from nucleation sites, bearing some similarities with crystallization.…”

Section: Ordering Kineticsmentioning

confidence: 99%

“…15 Deep quench experiments have suggested the existence of limits to the nucleation process and the occurrence of spinodal-like decomposition. [10][11][12][13][14] The Avrami model describes the relaxation into the new equilibrium after a fast quench. [10][11][12][13][14] The Avrami model describes the relaxation into the new equilibrium after a fast quench.…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of the shear-induced isotropic-to-lamellar transition of an amphiphilic model system: A nonequilibrium molecular dynamics simulation study

Guo

Kremer

2007

The Journal of Chemical Physics

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The shear-induced isotropic-to-lamellar phase transition in the amphiphilic systems in the vicinity of the quiescent order-to-disorder transition point is investigated by the large-scale parallel nonequilibrium molecular dynamics simulations of simple amphiphilic model systems. There is a shear-induced upward shift of the ordering temperature. The initial isotropic phase orders into a lamellar phase perpendicular to the shear vorticity. The phase diagram as a function of temperature and shear rate is established. The dependency of the ordering transition on interaction strength and shear rate is rationalized by the competition between shear rate and chain relaxation. The time evolution of morphology reveals that the shear-induced ordering proceeds via nucleation and growth, a signature of a first-order phase transition. At low shear rate, a single ordered domain grows after an incubation period. With increasing shear rate ordering speeds up, but eventually develops in a lamellar system with disordered shear bands. The time dependence of the order parameter follows that of the mean-squared end-to-end distance, shear viscosity, and bulk pressure, and follows an Avrami scheme with an Avrami exponent between 2 and 4.

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Section: Introductionsupporting

confidence: 83%

Section: Ordering Kineticsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetics of the shear-induced isotropic-to-lamellar transition of an amphiphilic model system: A nonequilibrium molecular dynamics simulation study

Guo

Kremer

2007

The Journal of Chemical Physics

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“…Although the static properties have been studied extensively, much less attention has been devoted to the kinetics near the microphase separation [6,7]. The first rheological study [6] on the ordering kinetics was made on the system PEP-PEE and revealed a narrow temperature range below the order-disorder temperature T o D T within which the ordering process can be observed.…”

Section: Introductionmentioning

confidence: 99%

Ordering kinetics in a symmetric diblock copolymer

et al. 1994

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Small angle X-ray scattering (SAXS) and rheology are employed to study the microphase separation transition in a symmetric poly(styrene-b-isoprene) diblock copolymer. The order-disorder transition temperature Toor has been identified with a good precision ( ToDT =359 K) and the interaction parameter is extracted using mean field theory at temperatures well above TODT. The kinetics of microphase separation have been studied by means of rheology in a small temperature range below the order-disorder transition, following a quench from the disordered state.The time evolution of the storage and loss moduli exhibited shapes which are reminiscent of the crystallization isotherms of semicrystalline materials (of the Avrami type). For shallow quenches, we find a temperature range of 3 K below To,, where the ordering proceeds by heterogeneous nucleation and growth of three-dimensional objects with lamellar microstructure. At higher undercooling, the kinetic curves change in form, indicating a different mechanism of structure formation. Our results are compared with theoretical predictions for the ordering kinetics of symmetric diblocks.

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“…Structure formation in block copolymers has been extensively studied from both theoretical and experimental view points [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] . In block copolymers composed of only amorphous components, the driving force for structure formation is the incompatibility between the block chains, characterized by c N t , where c is the Flory interaction parameter and N t is the total number of segments in the copolymer.…”

Section: Introductionmentioning

confidence: 99%

Structure Formation and Crystallization Behavior of Ethylene-Isoprene Block Copolymers and Their Blends with Corresponding Homopolymers

et al. 2008

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Time-resolved simultaneous synchrotron small-angle X-ray scattering and differential scanning calorimetry experiments have been performed on crystallization of polyethylene-polyisoprene diblock copolymers (HEI or LEI) and their blends with corresponding homopolymers, polyethylene (PE) and polyisoprene (PIp). For the neat block copolymer having a 50 wt% of the crystalline component, preexisting microphase separation structure in the melt was kept at high and low crystallization temperatures T c (T c Ն94°C and T c Ͻ60°C), while disrupted at intermediate T c (60°CՅT c Ͻ94°C). This complex behavior was interpreted by combination of two mechanisms. The behavior in the crystallization below 94°C was attributed to the competition between the crystallization and chain diffusion rates, that is, the fast crystallization rate at lower T c makes it difficult to rearrange the phase structure in the melt. On the other hand, at a higher T c (Ն94°C), the preservation of the microphase separation structure was explained by a small degree of crystallinity due to the ethyl branch of polyethylene (hydrogenated poly(butadiene)). For HEI/PE blends, crystallization behavior was the simple superposition of those for HEI and PE, while, for HEI/PIp with a small composition of PE, suppression of crystallinity was observed. Crystallization kinetics in the neat block copolymer and all the blends was not so different from that in the PE homopolymer.Keywords Microphase separation, Structure formation, Crystallization, Polyethylene-polyisoprene block copolymer. Regular Articlee-Journal of Soft Materials, Vol. 4, pp. 12-22 (2008) amorphous component T g A 19,20) . When crystallization temperature T c is lower than T g A , that is, the amorphous component is in glassy state at T c , microphase separation structure in the melt is usually maintained in crystallization, because the microphase separation structure is frozen by the glassy domains 19,21,22) . On the other hand, when T c is higher than T g A , it has been reported that structural change in crystallization depends on the segregation strength between components (cN t ). Quiram et al. explored the crystallization of a high molecular weight polyethylene-poly(3-methyl-1-butene) block copolymer (strongly segregated system) with a polyethylene weight fraction f E of 0.27, and found that polyethylene crystallized within preexisting cylindrical microdomains 23,24) . Nojima et al. 25) also investigated a crystallization process of crystalline-rubbery amorphous block copolymers for poly(e-caprolactone)-polybutadiene (weakly segregated system) through a time-resolved smallangle X-ray scattering (SAXS) technique using synchrotron radiation as a light source, and observed that a preexisting SAXS peak from the microphase separation disappeared with development of a new peak originating from the long period of crystal lamellae. Furthermore, we have reported that a high molecular weight poly(ethylene glycol)-poly(butadiene) block copolymer (PEG-PBD), which is relatively strongly segrega...

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Dynamics of structure formation at the microphase separation transition in diblock copolymers

Cited by 36 publications

References 6 publications

Kinetics of the shear-induced isotropic-to-lamellar transition of an amphiphilic model system: A nonequilibrium molecular dynamics simulation study

Kinetics of the shear-induced isotropic-to-lamellar transition of an amphiphilic model system: A nonequilibrium molecular dynamics simulation study

Ordering kinetics in a symmetric diblock copolymer

Structure Formation and Crystallization Behavior of Ethylene-Isoprene Block Copolymers and Their Blends with Corresponding Homopolymers

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