Rheo‐optical characterization (flow‐birefringence and flow‐dichroism) of the Tobacco Mosaic Virus

Reinhardt, Ulf; Groot, Eleanor L. Meyer de; Fuller, Gerald G.; Kulicke, Werner‐Michael

doi:10.1002/macp.1995.021960103

Cited by 11 publications

(5 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[53] If aggregates are degraded until a shear-stable conformation is achieved, the ratio of dichroism to birefringence becomes constant again beyond a critical shear rate, as it is the case for an aqueous TMV solution. [35,54] From Fig. 18, however, can be seen that there are two regions of differing degradation.…”

Section: Influence Of the Molar Degree Of Substitution On The Physicamentioning

confidence: 98%

See 1 more Smart Citation

Rheological characterization of aqueous hydroxypropyl cellulose solutions close to phase separation

Roschinski

Kulicke

2000

Macromol. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

The influence of temperature, concentration, shear rate and degree of substitution on the molecular structure of aqueous hydroxypropyl cellulose solutions (HPC) was investigated by means of rheo‐mechanical and rheo‐optical methods. During the investigations, it was possible to demonstrate the formation of supramolecular structures, even before visual or rheo‐mechanical confirmation, through the detection of dichroism in the shear field at T = 39°C shortly before the flocculation temperature at TF = 40°C. In addition, birefringence experiments and mechanical oscillation investigations showed that this conformational change of the segments was dependent upon the polymer concentration and the shear rate. The aggregated structure of the 0.6% HPC was elastic and easily degradable under shear, whereas the 1.5% solution was less elastic and the aggregates could only be degraded at higher shear rates. At high shear rates it is presumed that a conformation change in the HPC segments for 0.6–1.5% solutions led to the development of a second shear‐stable aggregate structure. It was therefore not possible to perform a uniform normalization of the birefringence in the semi‐concentrated solutions and compare it with phenomenological theories for the temperature range at T = 39°C due to differences in conformation that were dependent upon concentration and shear stress. The influence of the molar substitution, MS, at T = 39°C on the formation of supramolecular HPC structures was significant for 1.5% solutions. Beyond a MS > 6, the birefringence increased by over a decade as a function of the shear rate.

show abstract

Section: Influence Of the Molar Degree Of Substitution On The Physicamentioning

confidence: 98%

“…The design principles of this apparatus have been described in previous work. [33,34,35] Solutions that have already been investigated including those of TMV, xanthan, [36] polyurethane, [37] j-carrageen [38] and CMC. [39] Results and discussion…”

Section: Rheometrymentioning

confidence: 99%

Rheological characterization of aqueous hydroxypropyl cellulose solutions close to phase separation

Roschinski

Kulicke

2000

Macromol. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, turbidity alone does not allow one to measure both the dichroism and orientation angle of the distribution; moreover, turbidity requires rather concentrated systems. The drawbacks of turbidity measurements can be overcome by using linear flow dichroism. , Measuring the time- or rate-dependent evolution of the linear flow dichroism has the ability to elucidate the nature of particle motion and the average degree of alignment simultaneously and can be used even for nanoparticles. − Flow dichroism has been used in the past to study both rodlike and disklike nanoparticles in suspension. ,− In all cases where disklike nanoparticles are studied, the particles were made of stiff materials such as clay or gold. ,, Using flow dichroism and static light scattering, we study the behavior of functionalized graphene sheets (FGSs) in dispersion to investigate their 2D nature in suspension. Graphene oxide sheets have been suggested to exist in a crumpled state, , but more precise experiments found only relatively flat configurations .…”

Section: Introductionmentioning

confidence: 99%

Rheo-optical Analysis of Functionalized Graphene Suspensions

et al. 2018

View full text Add to dashboard Cite

Wet processing of graphene sheets is a potentially interesting route for the economically viable creation of graphene-based composites. In the present work, flow dichroism and small-angle light scattering are used to investigate the dispersion of functionalized graphene sheets in a suspension and their response to shear flow. In line with expectations from scaling theory at rest, the functionalized graphene sheets are present as Brownian flat sheets, and there is no evidence of significant crumpling. More surprisingly, we find that the rate-dependent orientation of these molecularly thin sheets can be described by numerical predictions for hard spheroidal sheets, making quantitative predictions of the flow-induced orientation possible. Further comparison of the flow-induced orientation of thick gold decahedra with the thin graphene sheets shows that, except for effects of polydispersity, the flow-induced orientation is predicted well quantitatively. Adequate prediction of the effects of flow on the orientation of graphene sheets makes it possible to design wet processed graphene-based composite materials.

show abstract

“…These changes for anisotropic particles are directly related to change in the microstructural state [17][18][19][20][21][22]. Successful applications of this optical technique to determine flow-induced alignment of rodlike and disklike materials have been reported [15,21,[23][24][25][26][27][28][29] but they have been mainly focusing on steady-state shear flow or simple transient shear flow. In the present work we probe the orientation evolution in transient oscillatory flow for molecularly thin functionalized graphene sheet suspension.…”

Section: Introductionmentioning

confidence: 99%

Orientation dynamics of dilute functionalized graphene suspensions in oscillatory flow

et al. 2018

View full text Add to dashboard Cite

The dynamics of molecularly thin graphene sheets in transient flows are important to understand their behavior in suspension and during processing. Scattering dichroism is used to evaluate changes in the orientation distribution function in dilute suspensions. To evaluate if the graphene sheets behave as flexible sheets or as more rigid flat particles, the results are compared with numerical computations of the single-particle Smoluchowski equation for flat spheroidal particles. In particular, the evolution of the orientation angle in oscillatory flows as a function of increasing amplitude is studied. The results show that even when taking an average rotational diffusivity, the results for the polydisperse graphene sheets show all the hallmarks of the motion of rigid disks, including a frequency doubling of the time-dependent orientation signal. The results indicate that the motion of functionalized graphene sheets in suspension is consistent with flat rigid objects.

show abstract

Rheo‐optical characterization (flow‐birefringence and flow‐dichroism) of the Tobacco Mosaic Virus

Cited by 11 publications

References 19 publications

Rheological characterization of aqueous hydroxypropyl cellulose solutions close to phase separation

Rheological characterization of aqueous hydroxypropyl cellulose solutions close to phase separation

Rheo-optical Analysis of Functionalized Graphene Suspensions

Orientation dynamics of dilute functionalized graphene suspensions in oscillatory flow

Contact Info

Product

Resources

About