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Quantification of Fractal Systems using Small Angle Scattering

Rai, Durgesh K
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377870724

Abstract Details

, PhD, University of Cincinnati, Engineering and Applied Science: Materials Science.
A recent method to quantify molecular topologies of various materials using small-angle scattering has been used to quantify fractal systems like polymer solutions and ramified aggregate structures. Small angle x-ray and neutron scattering has been used to characterize ceramic aggregates and polymer systems respectively. Ramified aggregates are formed in many dynamic processes such as in flames. Such structures are disordered and present a challenge to quantification. The topological quantification of such nanostructured materials is important to understand their growth processes. Small-angle X-ray scattering (SAXS) is widely used to characterize such nanoparticle aggregates. The details in ceramic aggregates like branch fraction, number of segments in an aggregate and the short circuit path, coordination number and the number of end groups are extracted. In order to explicitly determine the nature of chain scaling, related to topology or solvent quality, as well as to quantifying the thermodynamic interactions, the coupling of the unified scattering function with the Random Phase Approximation (RPA) equation and inter-arm interactions based on Benoit’s approach is proposed to enable analytical quantification of these effects using a scaling model. The scattering function places structural constraints from the model to limit the Unified Fit Function for hierarchal scattering. A detailed topological quantification of star polymer systems has been able to describe both, good and theta solvent conditions along with effect of functionalities, as well as resolve deviations in chain conformations due to steric interactions between star arms. An investigation on different solvent conditions for 6-arm polyurethane star polymers was done and the scaling parameters were extrapolation to zero entropy collapsed and extended chain states to understand the possible topological variations in the system. Polyisoprene star polymers under good solvent condition were used to study the effect of functionality on topology of star polymers using the RPA and inter-arm interaction equations, both coupled together with Unified Function to analyze the Small-angle neutron scattering data.
Gregory Beaucage, Ph.D. (Committee Chair)
Jude Iroh, Ph.D. (Committee Member)
Vikram Kuppa, Ph.D. (Committee Member)
Vesselin Shanov, Ph.D. (Committee Member)
137 p.
Materials Science
Small-Angle X-ray Scattering; Aggregates; Scaling Model; Small-Angle Neutron Scattering; Star Polymers; Unified Fit

Recommended Citations

Citations

  • Rai, D. K. (n.d.). Quantification of Fractal Systems using Small Angle Scattering [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377870724

    APA Style (7th edition)

  • Rai, Durgesh. Quantification of Fractal Systems using Small Angle Scattering. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377870724.

    MLA Style (8th edition)

  • Rai, Durgesh. "Quantification of Fractal Systems using Small Angle Scattering." Doctoral dissertation, University of Cincinnati. Accessed MAY 18, 2025. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1377870724

    Chicago Manual of Style (17th edition)

ucin1377870724
685
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This open access ETD is published by University of Cincinnati and OhioLINK.
Release 3.2.12