(4db) Structure-Property Relationships in Edible and Nonedible Polymers

The overarching theme of my research is to understand the structure-property relationships of edible and non-edible polymers using various experimental characterization methods. The design of materials with optimal properties necessitates the development of an understanding of relationships between structure, properties and material processing at different length scales. These understandings extend beyond simply academic interest and concern food science, human health, bioengineering, and rational design of industrially critical materials.

The characterization methods I have used for my investigations include rheology (bulk and micro shear rheology, extensional rheology), time and spatially resolved structure characterization using small angle scattering (small angle X-ray scattering and small angle neutron scattering) and imaging techniques involve atomic force microscopy and X-ray microtomography. I have also developed a method based on wavelet transform to track the confined motion of particles in dense systems to understand the micro-rheology.

A major part of my graduate and postdoctoral research has involved experimental investigation, either directly or through collaboration. In my present postdoctoral research, I am developing plant-based formulations which mimic the actual meat and dairy based products. In my previous postdoc research, I have tuned the self-assembly of diamagnetic block copolymer solutions using external magnetic field. In my graduate research, I have studied the fundamental origin of compressibility in ice templated highly filled polymer composites.

Research Experience:

• Developing low salt, sugar and plant-based food formulations

(Ongoing postdoctoral research advised by Prof. Vivek Sharma, University of Illinois, Chicago. The position is funded by Motif FoodWorks, Boston, MA)

My main objective is to develop plant-based formulations which can mimic texture and taste of artificial meat and non-dairy products with low salt and sugar content. The currently available plant-based products leave something to be desired in terms of the functionality and sensory properties. In our study we apply interfacial and advanced rheological techniques including dripping onto substrate (DoS) extensional rheometry developed by Vivek Sharma and group to plant-based food formulation in novel ways. This could uncover critically missed insights and enable an entirely new set of food design rules.

• Engineering the self-assembly structure of block copolymers (BCPs) using external fields

(Postdoctoral research advised by Prof. Michelle Calabrese, University of Minnesota-Twin Cities).

External stimuli such as shear, electric and magnetic fields have been used to tune the structure and properties of polymer melts. The magnetic fields provide a route for controlling the alignment of soft materials, including homopolymers and BCPs. Most prior work in this area has relied either on the application of high intensity magnetic fields (>5T) or on the presence of anisotropic liquid crystalline species and/or aromatic groups to ensure sufficient magnetic anisotropy to drive alignment. My studies on aqueous polyethylene oxide (PEO) and “isotropic” spherical micelles of PEO-containing BCPs, however, showed an anomalous response to low intensity magnetic fields (B>0.05 T). The major characterization methods involved in this study were rheology, SAXS and SANS. The impact of linear viscoelastic magneto-shear rheology showed a reversible three-to-six orders increments in dynamic moduli under low field strengths (<0.5 T); magneto X-ray scattering revealed a disorder-to-order structural transition led to the change in mechanical properties. Polymer solutions exhibited diamagnetism with low magnetic susceptibility anisotropy (∆χ~10^-10) and that confirmed the sample purity. This field induced assembly was time-dependent, where the critical response time was a function of polymer molecular weight, temperature, and field intensity. In addition to field-induced phase transition, an unexpected phase orientation was also observed at low ∆χ and field intensity. Therefore, this study showed a facile way to alter the flow properties of polymer solutions by low intensity magnetic fields.

• Structure property relationships of highly filled yet highly compressible polymer composites.

(PhD research advised by Prof. Guruswamy Kumaraswamy (IITB), in collaboration with Prof. Sanat K. Kumar (Columbia University), Prof. Arindam Chowdhury (IITB), Prof. M G Basavaraj (IITM), Prof. Shivprasad Patil (IISER-Pune) and Prof. Ravi Kumar (CSIR-NCL))

My Ph. D research was focused on structure-property relationships of highly loaded ceramic-polymer composites made by ice templating. Here, we have developed a flexible macroporous material primarily made of ceramic particles (90 wt.%) by ice templating. The mechanism that underlies the flexibility of this remarkable material was studied by characterizing the materials from bulk to nanometer scales using bulk and micro (single particle tracking) rheology, small angle scattering (SAXS, SANS), atomic force microscopy and 3D X-ray microtomography. Here, I have also developed a method based on wavelet transform to overcome the stage drift during microscopy imaging. This work has led to material-specific publications, as well as a publication on new analysis methods for micro-rheology. This multipronged strategy to investigate these materials at various length scales, using different experimental tools provided me an opportunity to collaborate with various research institutes.

Teaching Interests:

Teaching and mentoring younger students are part of my motive to continue working in academia. So far, I had the privilege to mentor/supervise three undergraduate students and two graduate students and help them develop the required research skills. I am interested in teaching courses in the chemical, polymer, materials science engineering syllabi in graduate and undergraduate levels. In particular, concepts of soft matter systems, polymer physics, colloids and interfaces, soft matter rheology and engineering materials and it’s characterization, all of which fit well with my background. I also intend to design upper-level course on advanced materials characterization techniques, more specifically focused on soft materials. The course would focus on general scattering methods, where the theoretical and experimental aspects of light, x-rays and neutron scattering would be covered, as well as advanced methods like flow-small angle scattering and insitu magneto-scattering. The course would also cover basic and advanced rheological techniques and would be of interest to both undergraduate and graduate students in chemical engineering, materials science, mechanical engineering and physics. I am open to accept other topics and not afraid of taking over courses that are not in my area of expertise.

Teaching Experience:

1. “Small angle scattering” for 2018 CSIR-NCL graduate level course

Selected Awards and Successful Proposals:

1. IIChE Shah-Schulman Award for the best Ph.D. thesis in India in the area of Colloid and Interface Science 2019
2. Beamline proposals: NGB-30 SANS, NIST, Feb2020 cycle, ANL-APS 05-1D-D synchrotron SAXS, 2020-3 cycle (co-author)
3. Best oral presentation award in NCL RF Annual Student Conference at CSIR NCL 2018
4. Best poster presentation award in CompFlu 2017 held at IIT Madras, December 2017
5. Best poster presentation award in National Science Day celebration at CSIR NCL 2017
6. Best poster presentation award in National Science Day celebration at CSIR NCL 2016
7. Selected candidate for attending the 8th AONSA Neutron School (Nov.15-19 at BARC, India) 2016

Selected Publications:

1. Karthika Suresh, Hisay Lama, MG Basavaraj, Dillip K. Satapathy and Guruswamy Kumaraswamy*, “Ice templated nanocomposites containing rod-like hematite particles: Interplay between particle anisotropy and particle-matrix interactions”, J. Appl. Phys. 2020, 128, 034702.
2. Karthika Suresh, Arindam Chowdhury, Sanat K. Kumar* and Guruswamy Kumaraswamy*, “Critical role of processing on the mechanical properties of cross-linked highly loaded nanocomposites”, Macromolecules, 2019, 52, 5955-5962.
3. Karthika Suresh, Marleen Häring, Guruswamy Kumaraswamy* and David Díaz Díaz*, “On the sensitivity of alginate rheology to composition”, Soft Matter, 2019, 15, 159-165.
4. Karthika Suresh and Guruswamy Kumaraswamy*, “Effect of electrostatic interactions on structure and mechanical properties of ice templated colloid-polymer composites”, J. Phys. D. Appl. Phys. 2019, 52, 214002.
5. Karthika Suresh, Dharmendar Kumar Sharma, Ramya Chulliyil, Ketan Dinkar Sarode,V. Ravi Kumar, Arindam Chowdhury* and Guruswamy Kumaraswamy*, “Single particle tracking to probe the local environment in ice- templated crosslinked colloidal assemblies”, Langmuir, 2018, 34, 4603–4613.
6. Karthika Suresh, Shivprasad Patil, Pattuparambil Ramanpillai Rajamohanan and Guruswamy Kumaraswamy*, “The template determines whether chemically identical nanoparticle scaffolds show elastic recovery or plastic failure”, Langmuir, 2016, 32, 11623–11630

To see the complete list:

https://scholar.google.co.in/citations?hl=en&user=hYJlf2IAAAAJ&view_op=l...