Sriram Sundararajan - US grants

Development of Smart Nanotribological Surfaces using Multifunctionalized Mesoporous
Nanosphere Films

With the current development of technology, a stricter requirement for controlling tribological phenomena (friction, wear and lubrication) at desired levels is arising in various engineering practices, especially in micro/nanoscale systems. Traditional tribological systems exhibit two weaknesses - the inability to adapt to changes in operating conditions to provide uniform tribological response and the durability of the tribological interface. Designing 'smart' films that exhibit self-adapting behavior to changes in operating conditions 'self-repairing' or 'self-healing' behavior would be extremely beneficial. Mesoporous Nanosphere Materials (MNMs) are a novel class of materials that exhibit a high degree of molecular design control of its internal pores and external surfaces, which can be taken advantage of to realize tribological films that are adaptive and self-healing.

The research objectives of this proposal are to design novel tribological coatings/film systems utilizing mesoporous silica/alumina nanosphere materials that (i) can provide superior tribological performance for
micro/nanoscale applications; (ii) are self-adapting ('smart') to changes in operating conditions and (iii) are self-healing to provide enhanced durability and longevity in tribological performance. Each phase involves chemical synthesis, deposition and chemical, structural, mechanical and tribological evaluation of each material system. The first phase of the proposed research program involves the synthesis and deposition of a closely packed monolayer of MNMs that are rigidly linked to the substrate. The second phase involves designing self-adaptive films using (a) MNMs that are internally functionalized using grafted monolayers incorporating a thermosensitive polymer (Poly-(N-isopropylacrylamide) (PNIPAAm)) which will cause a change in the frictional response of the surface below and above the lower critical solution temperature (LCST) of the polymer; (b) a self-lubricating hybrid self-assembled monolayer-nanoparticle surface utilizing MoS2 and graphitized carbon nanoparticles. The nanoparticles, being self-lubricating in nature at low and high humidity respectively, will aid in maintaining a uniform friction response of the surface. The third phase involves the design of a 'self-healing' tribological surface incorporating self-assembled monolayers (SAMs) and MNMs - a SAM covered surface with pockets of MNMs will be fabricated using photolithography and SAM chemistry. The MNMs will be externally functionalized with a polymer layer with tribological characteristics similar to that of the surface SAMs while internal pores will house free SAM molecules in solution. Wear or surface fracture initiated release of SAM molecules will allow active adsorption of molecules onto worn sites thus performing a 'self-healing' action. Micro/nanoscale tribological characterization will be performed using atomic force microscopy and microtribometry techniques developed at the PI's laboratory while synthesis of MNM films will be performed via techniques established by the co-PI.

The intellectual merits of the interdisciplinary research efforts include the development of novel and innovative design strategies to produce 'smart' tribological surfaces and obtaining a better understanding of chemical and physical phenomena associated with molecular design of materials and tribological behavior. The realization of such 'smart' systems would be extremely rewarding for tribological pairs subjected to multiple and repeated environmental changes and which require very high durability, which can occur in consumer, defense, aerospace and medical applications. In addition, the research demonstrates molecular design strategies that provide ways to obtain a high degree of control in tailoring the structure and behavior of the final system. Two Ph.D. students will work on the project. They will be exposed to cross-disciplinary research and benefit from the learning experience. In order to enhance the participation of women and minority students in graduate education and research, students from these underrepresented groups will be targeted for work on the project. Research results will be disseminated into several undergraduate and graduate courses being taught by the PIs in Mechanical Engineering and Chemistry that will enhance the education of about 200 students every year. The broad impacts of the proposed activities are (i) the research activities promote interdisciplinary research efforts in system design that can lead to novel engineering strategies for superior tribological interfaces in a wide range of applications (ii) they promote increased participation of women and/or minority students through targeted recruitment efforts and (iii) the research activities enhance the education of undergraduate and graduate students of two departments at Iowa State University by emphasizing the importance of interdisciplinary research and nanoscale design strategies.

The objective of this proposal is to obtain partial funding to support the travel of a delegation of scientists from the United States to attend the third ESF NANOTRIBO conference to be held on September 18-22 at Sesimbra, Portugal. The delegation will consist of 12 established and up and coming researchers from various universities and national research labs across the United States with strong expertise in nanotribology and who have been approved by the organizing committee. The research expertise of the group encompasses experimental and theoretical/modeling work which is in line with the aim of the conference to promote collaborations between experimentalists and theoreticians in the field of tribology on the nanometer scale. Funds requested will be used to cover part of the travel costs of the delegation to attend the conference. The conference will cover the room and board expenses of the delegation. The participation of
the delegation will aid in fostering collaborative research relations
between nanotribology researchers in the United States and in Europe. Some activities that will be pursued as a result of participation in the conference include student exchange programs, visiting faculty
opportunities, collaborative research proposals between delegation members and members of the European research community and establishing relations with top researchers in Europe to organize future joint research workshops and conferences on nanotribology and related themes.

NER: Active Nanotribological Surfaces Using Monomolecular Films
PI: Sriram Sundararajan (Iowa State University)

Abstract

This proposal was received in response to Nanoscale Science and Engineering initiative, NSF 05-610, category NER. The objective of this research is design molecularly thin films that allow active manipulation of their surface energy and tribological (friction, lubrication and wear) behavior through the application of electric fields. The approach is to investigate two candidate alkanethiol based molecule systems using combined experimental and computational studies that include 1) synthesis, chemical and structural characterization of candidate films; 2) computational studies to qualitatively predict and understand the effect of electric fields on film behavior and 3) experimental tribological characterization of films in response to electrical fields.

Successful demonstration of the proposed research strategy can lead to applications in a whole range of industrial and consumer mechanical systems in which energy and economical losses associated with friction/wear can be significantly reduced. The films can also be used in systems where friction behavior needs to be controlled on demand such as biomaterial research (cells, tissues, fluid studies) and consumer applications (footwear for all-year traction). The project will also enhance undergraduate and graduate education by incorporating research results into engineering courses and leveraging freshman honors/student workstudy programs at Iowa State University to include undergraduates in research.

The objective of this proejct is to develop a predictive model for predicting rheological behavior of cement-based materials. Using a coupled immersed boundary method (IBM) - discrete element method (DEM), the model will link individual particle behavior to the bulk rheological behavior of cement-based materials at multiple scales. The major research activities will include (1) utilizing atomic force microcopy (AFM) experiments to calibrate/validate a coupled IBM-DEM model and to capture the interparticle interactions in a cement system (nanoscale); (2) establishing a refined coupled IBM-DEM model to predict bulk rheological behavior of a cement paste in simple shear flow (mesoscale); and (3) assessing the predictive capability of the model via rheological experiments of various cement pastes (meso and macro scales). This research approach/methodology will eventually lead to better macroscale models of concrete in future.

Through experiments, theory and modeling, the project will provide a better understanding of the rheological behavior of cement-based materials. The developed model will permit more economical designs by optimizing mix proportions for specified rheological requirements in concrete practice. The information on the particle interaction can be adapted by the cement industry for modifying cement chemistry and physical properties during the cement manufacturing process. The proposed work requires interdisciplinary knowledge in concrete materials, multiphase flow modeling, and nanoscale surface engineering and mechanics, and therefore, students will be trained in a variety of complementary research techniques during this project.

0932573
Sundararajan

The objective of the research is to determine the thermal response of the near-apex region of a nanoprobe in response to ultrafast laser irradiation. This is an important aspect of atom probe microscopy measurements and photo-assisted scanning probe matter manipulation (nanomanufacturing). Current models do not predict temperatures accurately. Furthermore, identifying exact temperatures in the near-tip region of the probe is limited by the ability to experimentally verify the model predictions.

Intellectual Merit: The modeling approach will employ solutions of the Maxwell equation to obtain the optical field distribution in the vicinity of the probe tip. The energy transport within the nanoscale probe will be determined using a combined Lattice Boltzmann methodology and finite element technique. The resulting model will provide fundamental knowledge regarding the optical intensity distribution inside the nanoprobe as well as how, and to what extent the near-field laser heating affects probe temperatures. Experimental validation of the model will be achieved via laser assisted atom probe microscopy experiments.

Broader Impacts: This research is relevant to atom-scale characterization of materials using atom probe microscopy as well as a range of applications involving photo-assisted probe microscopy including but not limited to nanoscale biological, chemical sensing, and nanomanufacturing. Undergraduate and graduate education will be enhanced by (1) incorporating the research results into specific engineering courses (Scanning Probe Microscopy and Nanoscale Thermal Transport) taught at Iowa State; (2) partnering with freshman honors and student work-study programs to involve undergraduate students in the research; (3) mentoring and recruiting women students in conjunction with the Society of Women Engineers and (4) dissemination of research results through an on-campus NSF International Materials Institute.

This three-year REU Site program at Iowa State University is focused in the area of Microscale Sensing, Actuation and Imaging. Ten undergraduate students each year will pursue fundamental investigations in the area of design and manufacture of sensors, actuators and smart materials as well as imaging and diagnostic systems. The key components of this REU program include: 1) a research project chosen by the student and advised by a faculty member and graduate student; 2) a series of technical short courses; 3) professional development activities such as Lunch-n-learns with local researchers, workshops on career opportunities and graduate school, journal clubs and e-portfolio maintenance; 3) social and cultural events designed to complement the research activities; and 4) an REU Research Symposium to provide feedback on student work and to recognize exceptional achievement. Participants will also receive training in ethical implications of engineering. At the end of the REU Site program, students will present a paper discussing ethical issues raised by the research projects in which they participated and the research they may plan to pursue in their careers. Participants will be encouraged to present a technical paper/poster at the Annual International Mechanical Engineering Congress & Exposition (IMECE) or the Materials Research Society (MRS) meeting.

Recruitment efforts will be targeted to undergraduate students from 4-year colleges, community colleges and incoming freshman. A talented and diverse group of students will be recruited at a regional and national level, with special efforts that leverage College and University wide programs to attract women and minorities, namely the SPEED (a summer mentoring program for incoming women and underrepresented minority freshman) program, Program for Women in Science and Engineering and the Iowa-AGEP program.

Proposal Number: EPS-1101284

Proposal Title: Iowa EPSCoR: Harnessing Energy Flows in the Biosphere to Build Sustainable Energy Systems

Institution: Iowa State University

This Research Infrastructure Improvement project seeks to expand the research capacity within the state to support a transition in energy supply from subsurface fossil energy stores to renewable energy flows at or near the earth?s surface. The research program is organized into four platforms in renewable energy, each of which consists of several research foci (or planks) which are detailed below. The project seeks to examine energy flows and processes from a holistic systems perspective that considers technical, economic, social, and environmental constraints and impacts. This comprehensive program will enable innovative research, strengthen energy-related education, train a ?clean-tech? workforce, and engage diverse communities in implementing environmentally and economically sustainable solutions to the growing energy challenges facing Iowa and the U.S. The project brings together research universities, 2- and 4-year colleges, the private sector, and local government agencies (Iowa Power Fund, Iowa Office of Energy Independence), to address key issues related to renewable energy research, education, and workforce development in the state.

Intellectual Merit
This proposal seeks to significantly enhance the research competitiveness of Iowa through a comprehensive, multi-faceted research program in renewable energy and energy efficiency. The program builds upon existing strengths of Iowa in the areas of bioenergy and wind energy while including highly complementary components in the areas of energy efficiency and energy policy. The program seeks to change the energy landscape across Iowa by improving the energy balance while mitigating environmental concerns and positioning citizens to compete more effectively in a global economy.

Broader Impacts
An overarching goal of this project is to translate the knowledge gained in the research platforms into specific actions that can increase the participation of under-represented minorities in STEM fields. IA EPSCoR proposes the creation of the Future Leaders in Advancing Renewable Energy (FLARE) Institute to lead the implementation of strategic broader impacts activities. Modeled after the Iowa?s NSF I3 program, Strengthening the Professoriate at ISU, the FLARE Institute will be a state-wide organization supporting the human infrastructure development needed to accelerate Iowa?s transition to a green economy. Critical to this goal are strategies to broaden the participation of women, underrepresented minorities, and first-generation college students in the STEM fields, prepare a workforce that can meet the demands of Iowa?s emerging green economy, and create a community of scholars who integrate broader impacts into their research efforts in all fields. Accordingly, the FLARE Institute will address key deficiencies in state-wide infrastructure by integrating broader impacts through all elements of activities leveraged by IA EPSCoR, thereby having a far greater state-wide impact than any individual program could achieve on its own.

This Research Experiences for Undergraduates (REU) Site program at Iowa State University, offers state-of-the-art, multi-disciplinary research experiences in the areas of sensing, actuation and imaging, to diverse and talented cohorts of undergraduates from institutions with limited or no research opportunities. The need for advanced sensing and imaging technologies to enhance our nation's health, homeland, food and energy security has never been more urgent as evident from the NAE Grand Challenges. Research in sensing and imaging technologies has an obvious societal impact that appeals to a broad demographic of students. In addition, the multidisciplinary nature of the research, which merges engineering concepts with those in the sciences will help attract students from all engineering and non-engineering disciplines. This REU Site with a focus on sensing and imaging research will take advantage of shared research interests and synergistic interactions of the faculty to help increase graduate enrollment. The student experience will evolve from dependent to independent status and will enable them to acquire life-long skills that will impact their contributions to science and engineering and to society.

The primary goal of this renewal REU Site program is to provide each undergraduate participant with a ten-week scientifically rigorous, intellectually demanding, research experience within a highly collegial environment of collaboration with faculty and other students. The program focuses on the development of the technical skills and critical-thinking abilities of the participants and on their exposure to substantive, representative research investigations related to design and manufacturing of sensors, actuators and smart materials; state-of-the-art imaging and diagnostic systems and data driven approaches to sensor/device design and reliability. Project topics include microfluidic devices, nanomechanical sensors for biological agents; nanoenergetics imaging, bioprosthetics, nanomaterials synthesis, and reliability of implantable sensors. The program will also include weekly seminar series; short courses; communication workshops; interactions with middle school teachers; organized social and cultural events designed to complement the research activities; a REU Research Symposium to provide feedback on student work and exceptional achievement; and training in ethical implications of engineering that will be conducted by ISU's Bioethics program. Participants will also be encouraged to present a technical paper/poster at regional and national conferences within one year of participating in this program.

This site is supported by the Department of Defense in partnership with the NSF REU program.

The proposed effort consists of increasing awareness amongst Iowa State University faculty about opportunities in research, education and outreach that engage individuals with disabilities. This objective will be achieved by through a series of three workshops on campus that will cover national and local perspectives and highlight opportunities, case studies and best practices in this arena. Persons with disabilities are severely underrepresented in the science, technology, engineering, and mathematics (STEM) fields of study. This group consists of an entire population of lifelong problem solvers. Engaging them into the STEM educational pipeline and the STEM workforce is to the benefit of national interests. The efforts of the workshop will contribute to faculty development at Iowa State University by enhancing their understanding of 1) diversity and inclusivity with respect to persons with disabilities and; 2) opportunities, resources and best practices in engaging persons with a wide range of learning abilities. Consequently the project stands to broaden participation of under-represented groups in STEM, broaden the research and education portfolio at Iowa State University and contribute to STEM workforce development for the nation. Finally, the dissemination of findings from the workshops will help educate broad communities in the state and nation on these topics.

The proposed effort is to increase awareness amongst Iowa State University faculty about opportunities in research, education and outreach that engage individuals with disabilities. This will be achieved through a series of three on-campus workshops: 1) Research and Outreach, focusing on technical research that addresses challenges faced by persons with disabilities; 2) Universal Design I, introducing the concept of making educational environments and products more inclusive for all students, staff, faculty and visitors and; 3) Universal Design II, which will feature presentations by faculty and staff who have implemented universal design into their courses and a tutorial of existing resources at Iowa State. The findings, observations and recommendations from the workshops will be disseminated through publicly available websites at Iowa State University and via presentations/publications at ASEE national conferences and the Iowa NSF-EPSCoR annual meeting in Summer 2016. The workshops cover research aimed at 1) providing technical solutions to challenges faced by persons with disabilities and; 2) tools used for enabling access to instruction for students with a wide range of learning abilities. The proposed effort will also contribute to faculty development at Iowa State University by enhancing their understanding of 1) diversity and inclusivity with respect to persons with disabilities and; 2) opportunities, resources and best practices in engaging persons with a wide range of learning abilities. Consequently the project stands to broaden participation of under-represented groups in STEM and broaden the research and education portfolio at Iowa State University. Finally, the dissemination of findings from the workshops will help educate broad communities in the state and nation on these topics.