Micellization Kinetics in Block Copolymer Solutions:  Scaling Model

Dormidontova, Elena E.

doi:10.1021/ma9809029

Cited by 171 publications

(329 citation statements)

References 34 publications

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“…Some theories exclusively favor the classical Aniansson-Wall mechanism [11]-a step-by-step insertion mechanism of single molecules (unimers) [3,[12][13][14], while others emphasize the role of fragmentation or recombination mechanisms, i.e., fusion and fission of individual micellar entities [15,16]. Experimentally, appropriate data are scarce to find and what do exist are indirect in the sense that the structural evolution is not probed [17][18][19][20].…”

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Structural Observation and Kinetic Pathway in the Formation of Polymeric Micelles

et al. 2009

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The route by which amphiphilic molecules self-assemble into micelles is still not fully understood. In this Letter, we present direct structural information on the birth and growth of block copolymer micelles by means of synchrotron x-ray scattering with millisecond time resolution. Using a quantitative model, we show that the self-assembly process can be viewed as a nucleation and growth type process where the elemental growth mechanism is an exchange of single molecules. DOI: 10.1103/PhysRevLett.102.188301 PACS numbers: 82.35.Jk, 61.05.cf, 82.35.Lr, 82.70.Uv An archetypical example and a model system for self assembly is the family of amphiphilic A-B diblock copolymers that undergo micellization in aqueous solutions [1,2]. In such systems where the interfacial energy is usually large, the structure formation may be influenced by prominent kinetic barriers leading to a variety of trapped metastable states unable to reach their global equilibrium [3][4][5][6][7][8]. Despite recent progress on manipulation of nonequilibrium structures via kinetic control, such as by sophisticated mixing protocols [6,9,10], a complete understanding of the physical mechanisms of the self-assembly process is still lacking. Therefore, a more fundamental approach to control and design such nanostructures is still a very challenging task.Concerning micellization kinetics in particular, theories predict various growth mechanisms. Some theories exclusively favor the classical Aniansson-Wall mechanism [11]-a step-by-step insertion mechanism of single molecules (unimers) [3,[12][13][14], while others emphasize the role of fragmentation or recombination mechanisms, i.e., fusion and fission of individual micellar entities [15,16]. Experimentally, appropriate data are scarce to find and what do exist are indirect in the sense that the structural evolution is not probed [17][18][19][20]. This is primarily due to the lack of experimental techniques having the correct spatial and temporal resolution with the combination of a suitable well-defined model system. In addition, there is a prominent lack of detailed physical modeling of the data. Thus, so far, results remain largely inconclusive.Here we show that the required nanoscale spatial and millisecond temporal resolution for an in situ investigation of micellization can be reached by using synchrotron x-ray scattering. The self-assembly process of a model amphiphilic block copolymer was triggered by an interfacial tension jump experiment by rapidly changing the solvent quality for one of the blocks. Using a detailed quantitative model, we further demonstrate that the kinetic pathway proceeds by unimer exchange where only single chains are added or removed at a time.As a model system, we employ a well-defined amphiphilic poly(ethylene-alt-propylene)-poly(ethylene oxide) (PEP1-PEO20, numbers indicate the approximate molecular weight in kg=mole) block copolymer [21]. Extensive previous studies have shown that these asymmetric PEP-PEO diblock copolymers form well-defined starlike micelles in w...

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Structural Observation and Kinetic Pathway in the Formation of Polymeric Micelles

et al. 2009

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“…To determine the probability of exceeding the flow through the specified bridge section the following formula should be used (6):…”

Section: Methodsmentioning

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“…The paper reports on the reliability of a road that includes the reliability of its elements-road surfacing, geometric elements, man-made structures [1][2][3][4][5][6][7].…”

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Determining the optimum length of a bridge opening with a specified reliability level of water runoff

Evdokimov

Dormidontova

2017

MATEC Web Conf.

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Abstract. Current trends in construction are aimed at providing reliability and safety of engineering facilities. According to the latest government regulations for construction, the scientific approach to engineering research, design, construction and operation of construction projects is a key priority. The reliability of a road depends on a great number of factors and characteristics of their statistical compounds (sequential and parallel). A part of a road with such man-made structures as a bridge or a pipe is considered as a system with a sequential element connection. The overall reliability is the multiplication of the reliability of these elements. The parameters of engineering structures defined by analytical dependences are highly volatile because of the inaccuracy of the defining factors. However each physical parameter is statistically unstable that is evaluated by variable coefficient of their values. It causes the fluctuation in the parameters of engineering structures. Their study may result in the changes in general and particular design rules in order to increase the reliability. The paper gives the grounds for these changes by the example of a bridge. It allows calculating its optimum length with a specified reliability level of water runoff under the bridge.

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“…Great improvements in city traffic can be achieved by taking urban planning measures such as bridge, tunnel and highway construction [4][5]. The development of such projects is expensive and time consuming.…”

Section: Introductionmentioning

confidence: 99%

Rationale for statistical characteristics of road safety parameters

Dormidontova

Evdokimov

2017

MATEC Web Conf.

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Abstract. When making engineering decisions at the stage of designing auto-roads and man-made structures it is necessary to take into account the statistical variability of physical and mechanical characteristics of the used materials as well as the different effects on the structures. Thus the rationale for the statistical characteristics of the parameters that determine the reliability of roads and man-made engineering facilities is of particular importance.There are many factors to be considered while designing roads, such as natural climatic factors, the accidental effects of the operating loads, the strength and deformation characteristics of the materials, the geometric parameters of the structure, etc. which affect the strength characteristics of roads and man-made structures. The rationale for statistical characteristics of the parameters can help an engineer assess the reliability of the decision and the economic risk, as well as avoid making mistakes in the design of roads and man-made structures.However, some statistical characteristics of the parameters that define the reliability of a road and man-made structures play a key role in the design. These are the visibility distance in daytime for the peak curve, variation coefficient of radial acceleration, the reliability of visibility distance and other parameters.

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Micellization Kinetics in Block Copolymer Solutions: Scaling Model

Cited by 171 publications

References 34 publications

Structural Observation and Kinetic Pathway in the Formation of Polymeric Micelles

Structural Observation and Kinetic Pathway in the Formation of Polymeric Micelles

Determining the optimum length of a bridge opening with a specified reliability level of water runoff

Rationale for statistical characteristics of road safety parameters

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