Rufina G. Alamo - US grants

9419508 Mandelkern The main objective of this research program is to improve our understanding of the thermodynamics, structure and properties of nonoriented, bulk-crystallized flexible-chain polymers. The research will be concerned with the interrelation between molecular, phase, and superstructures and crystallization kinetics and macroscopic properties. Carefully characterized molecular-weight and composition fractions of linear polyethylenes, as well as well-defined blends of these components will be studied. Small and wide- angle x-ray scattering will be used to investigate the phase structure. These studies will be correlated with thermal measurements and analysis of Raman spectra. The influence of the initial topology and melt structure on the resultant crystalline state will be investigated. Studies of tensile properties will be emphasized. Advantage will be taken of a recently constructed apparatus that only requires very small amounts of sample. Emphasis will be given to the influence of stain rate and temperature, as well as molecular and structural factors, on key tensile properties and the transition between ductile deformation and brittle failure. %%% These studies should give us a better understanding of the molecular and structural factors that govern macroscopic properties of crystalline polymers and improve the end-use of this class of polymers. ***

This award from the Instrumentation materials Research program to Florida State University is for the acquisition of a variable-temperature scanning probe microscope system. The instrument will be used for studying microstructures not only at the nano-scale but also on the meso-scale, particularly at high sample temperatures, with applications in thin film semiconductors, semi-crystalline polymers, high-temperature superconductors, and nanostructures of superplastic and precipitation hardening materials. Methods to extend the temperature range capability of atomic force microscopy (AFM) to temperatures in excess of 1500 K will be investigated by the addition of thermocouple sensors on the heat-sensitive probe assemblies, and modification of the sample mounting configuration to minimize the volume being heated. This extremely large temperature range will provide scientists from FAMU-FSU College of Engineering with the opportunity to observe and investigate in-situ such phenomena as superconductor vortex structures, crystal reorientation, texture evolution, internal stress development and phase transformation. The information obtained from SPM may be used to complement the data acquired with other techniques, and thereby expand knowledge of the micromechanisms of deformation and phase transformation. The surface atomic arrangement will be used to obtain texture in bulk materials, even at high temperatures. The instrument will be used for instruction at both the undergraduate and graduate level, providing the opportunity for students to work with a truly state-of-the-art instrument at the forefront of materials research.
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This award from the Instrumentation materials Research program to Florida State University is for the acquisition of a variable-temperature scanning probe microscope system. The relatively new field of scanning probe microscopy has opened up an enormous number of opportunities for detailed atomic-scale study of dynamic surfaces. The fundamental principle behind the technique is the precision electrical manipulation of a needle probe whose tip is less than one-thousandth the diameter of a human hair. Simply by changing the material of the needle probe, the instrument can be converted to respond to differences in magnetic field, temperature, electron density and even chemical reactivity- all on the atomic scale. This instrument is capable of performing measurements on samples over the temperature range of 25 degrees above absolute zero, to over 1500 degrees. This remarkable temperature range will enable users to investigate a wide range of surface phenomena and material properties, including high temperature superconductors, shape-memory metallic alloys, high-purity semiconductors, and novel types of polymer materials. The instrument will be maintained by the FAMU-FSU College of Engineering, a jointly managed program of Florida State University, and Florida A&M University, a Doctoral-granting historically black university. Approximately 50% of the engineering students are minorities, and over 25% are women. The instrument will be used for instruction at both the undergraduate and graduate level, providing the opportunity for students to work with a truly state-of-the-art instrument at the forefront of materials research.
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A grant has been awarded to the Florida State University under the direction of Dr. Fredrik Ronquist for partial support of the acquisition of a scanning electron microscope with a field emission gun, a variable-pressure specimen chamber, a cryotransfer unit, and an elemental microanalysis unit. The equipment will offer a number of microscopic examination techniques that are not available today in the north Florida region and will be used by biologists, chemists, engineers, and geologists at the Florida State University and the Florida Agircultural and Mechanical University and by colleagues at other universities and colleges in the region.

The field emission gun allows imaging with extraordinary contrast and large depth of focus at both low and high magnifications. It also gives greatly improved performance at low acceleration voltages, which allows high-magnification examination of uncoated samples or samples that have a tendency to charge and alter in the electron beam. The possibility of raising the pressure in the examination chamber by introducing a gas can also help in the examination of sensitive samples. The cryotransfer equipment is used for rapid freezing of a specimen for subsequent transfer in the frozen state into the microscope chamber. With this equipment it is possible to observe unfixed frozen material in its natural state. Finally, the X-ray microanalysis equipment allows analysis of the composition of the sample surface.

The new instrument will be used for a wide range of applications including studies of polymers; cellular and tissue details important in medical engineering; /Drosophila/ mutants; teeth and other skeletal structures in dinosaurs, birds and mammals; skeletal morphology of hymenopterans (ants, wasps and bees); flower morphology; and structure of clays and fossil diatom assemblages in deep sea sediments. Five research groups in Chemistry are studying different types of novel materials based on nano-scale manipulation. The new microscope equipment will support the research of many faculty members but will also be used in education and research training of underrepresented groups. Other examples of activities with broad impact that will benefit from the new equipment include Sir Harold Kroto's efforts to popularize science through the Vega Science Trust, the first free Internet broadcaster of science programs, and the MorphBank project, aimed at providing a web platform for international collaboration in image-based biological disciplines such as comparative morphology and biodiversity research.

TECHNICAL SUMMARY
This proposal unites academic research groups at the University of Virginia, Cornell University, and Florida State University with a leading polyolefin industrial scientist at ExxonMobil Research and Engineering Corporation. The research focuses on the development of novel polypropylene synthetic chemistry and an exploration of the fundamental physical phenomena underlying nucleation and growth in quiescent and flow-induced crystallization of semicrystalline polymers. Specifically, the PIs will use branching architecture as a tool to control nucleation and thereby manipulate the final crystalline morphology and macroscopic material properties.
The team assembled to achieve this goal is skilled in novel polyolefin synthesis, crystallization kinetics and structural characterization, rheology and flow-induced crystallization, and industrial polymer processing. Model isotactic polypropylene (iPP) materials, including narrow molecular weight distribution linear, star, H-, and comb polymers, will be synthesized with precisely controlled stereoregularity and location of branch points. Quiescent crystallization experiments will principally seek to ascertain: (1) the influence of increasing chain irregularity due to branching on the level of crystalline organization and relative content of the alpha and gamma phases in homopolymer samples; and (2) the type and conformation of branching architecture that enhances nucleation in blends with linear chains.
Flow-induced crystallization of linear and branched iPP blends will seek to determine: (1) how crystallization kinetics, nucleation density, degree of crystallinity, and crystalline structure are influenced by branching for fixed longest relaxation time; (2) if molecular architecture alters the local segmental orientation to promote nucleation; and (3) how polymorphism and morphology depend upon the number of arms (stars), ratio of branch to main chain molecular weight (H-polymers), and number of branch points (combs).
NON-TECHNICAL SUMMARY
Over 43 million tons of thermoplastic resins are produced in the U.S. each year with an estimated market value of over $65 billion. Much processing is performed in an ad hoc manner without the benefit of modeling or coherent blending strategies. Since the raw materials are often not renewable, waste in processing has a significant environmental impact. Moreover, the ability to exert better control over crystallinity and crystalline morphology will lead to better films, lighter weight parts, and also inject inexpensive PP materials into novel applications due to extended material properties. By providing quiescent and flow-induced crystallization data on well-defined material systems, theoretical tools allowing quantitative predictions of semicrystalline morphology are expected to result from this work. Students in Chemistry and Chemical Engineering will be not only be exposed to modern polymer synthesis and characterization, rheology, and material characterization techniques (e.g., X-ray scattering, birefringence, optical and transmission electron microscopy), but they will also be able to participate in industrial research experiences at ExxonMobil. The PIs will also combine their diverse talents and perspectives to assemble a K12 educational program on "Plastics" to be adopted in their respective communities. The PIs also have a record of including underrepresented groups in their research efforts (e.g., undergraduates from Ghana and Panama and several female undergraduates, graduates, and postdocs). Additionally, the FAMU-FSU College of Engineering is a jointly managed program of FAMU, a historically black college and university, and FSU with 40% minority and 25% female enrollment, and numerous African-American undergraduates have conducted undergraduate research in the laboratory of the PI at that institution.

This Nanotechnology Undergraduate Education (NUE) in Engineering program entitled "NUE: NanoCORE (Nanotechnology Concepts, Opportunities, Research and Education)at the Florida A&M University (FAMU)-Florida State University (FSU) College of Engineering", under the direction of Dr. Ongi Englander, is designed to introduce aspects of nanoscale science and engineering into the core undergraduate curriculum beginning in the freshman year. The NanoCORE program will infuse and integrate nanoscale science and engineering (NSE) as a permanent component of the undergraduate curriculum, present multiple opportunities for undergraduate learning of concepts in NSE and create opportunities for undergraduates to pursue nanotechnology related research activities.

The Colleges of Engineering and Departments of Chemistry at five large state universities in Florida will join together to form the Alliance for the Advancement of Florida's Academic Women in Chemistry and Engineering (AAFAWCE). The University of South Florida is the lead institution with four partners: Florida State University, Florida Agricultural and Mechanical University (FAMU), University of Florida, and Florida International University (FIU). The project will modify and adapt successful programs developed by previous ADVANCE projects focusing on the Colleges of Engineering and Departments of Chemistry at the partner institutions. The project will implement strategies for; 1) recruiting women in academic searches based on work developed at the University of Wisconsin, Madison; 2) transforming careers via leadership COACh workshops developed at the University of Oregon; and 3) advising and mentoring academic women at the assistant and associate levels based on work developed by the University of Texas-El Paso. In addition, the project will adapt and implement a faculty climate survey within all of the participating departments which was first developed by the Women in Science and Engineering Leadership Institute (WESLI) at the University of Wisconsin, Madison. The survey will be used to identify issues for faculty related to recruitment, mentoring, and the tenure process.

Intellectual Merit: The project will adapt previously developed strategies to a state-wide consortium of universities in Florida. The collaboration between the five institutions is important given the low numbers of female faculty in engineering and chemistry within these institutions. Faculty in each of the participating campuses' engineering and chemistry programs will participate in recruitment workshops along side department chairs, deans and other administrators. Faculty will have an opportunity to participate in the COACh workshop on advancing one's career and engage in a mentoring and advising program.

Broader Impacts: The project provides opportunities for female faculty at all ranks to engage in activities with others in their discipline areas from other Florida campuses as well as on their own campus. The collaboration includes two Minority-Serving Institutions; FAMU which is a Historically Black University and FIU which is a Hispanic-Serving Institution. This network will provide support for the faculty as they progress in their academic careers. The project will post videos of the workshops and other materials on the Global Educational Outreach web portal. In addition, the project team expects to publish a monograph with chapters by the project team on the objectives and activities of the program as well as by the participants in the alliance activities.
Intellectual Merit: The project will adapt previously developed strategies to a state-wide consortium of universities in Florida. The collaboration between the five institutions is important given the low numbers of female faculty in engineering and chemistry within these institutions. Faculty in each of the participating campuses' engineering and chemistry programs will participate in recruitment workshops along side department chairs, deans and other administrators. Faculty will have an opportunity to participate in the COACh workshop on advancing one's career and engage in a mentoring and advising program.

Broader Impacts: The project provides opportunities for female faculty at all ranks to engage in activities with others in their discipline areas from other Florida campuses as well as on their own campus. The collaboration includes two Minority-Serving Institutions; FAMU which is a Historically Black University and FIU which is a Hispanic-Serving Institution. This network will provide support for the faculty as they progress in their academic careers. The project will post videos of the workshops and other materials on the Global Educational Outreach web portal. In addition, the project team expects to publish a monograph with chapters by the project team on the objectives and activities of the program as well as by the participants in the alliance activities.

TECHNICAL SUMMARY

Research is proposed to advance knowledge of the interplay between chain microstructure, phase structure, crystallization kinetics and morphology of non-oriented bulk crystallized polyolefins. The aim is to understand this interplay using well-characterized systems that serve as models to predict the behavior of more complex commercial systems. Molecules could then be tailored with unique crystalline morphologies and properties. We seek to understand from first principles the role of crystallization kinetics on the development of the ultimate crystalline state. Of interest is the effect of undercooling on nucleus size, nature of folding when enabled, and impact in packing of sequence-specific macromolecules. Using polyethylene-based molecules with exquisite control in halogen substitution as model systems to predict kinetically controlled polymorphic transitions, further insights into primary chain deposition and subsequent arrangements are sought as they relate to classical and novel views of the path to polymer crystallization. In blends of metallocene-made poly(propylene) and higher alpha-olefin random copolymers, the role of sequence length distribution in polymorphic behavior and the crystalline phase structure that evolves will be addressed for a wide range of compositions.


NON- TECHNICAL SUMMARY

The main proposed work involves the two leading commercial polyolefins, polyethylenes and polypropylenes. As they comprise over half of the annual production of all synthetic polymers, any improvement in the product, either by branching architecture, rate of processing, or judicious component blending will lead to a significant impact in the US and world economy. Most properties of these polyolefins are directed by the fraction and type of crystalline order that they assemble, which is a function of branching content and distribution. Commercial polyolefins are too complex in chain length and branching distributions to generate fundamental relations between chain-structure and properties. In the work proposed, polyethylenes and polypropylenes synthesized with exquisite control of branching distribution, either at a precise regular spacing or randomly placed will be studied as models to establish fundamental behaviors. Special emphasis is given to the role of crystallization kinetics, as it relates to processing rate, in the type of crystals assembled. Crystals with different degrees of symmetry are predicted with the model systems, thus bringing the opportunity to develop new polyolefins in which polymer primary structure can be manipulated to control physical properties. This fundamental research is also aimed to provide learning opportunities for both graduate and undergraduate students, many of them minority.

The Nanotechnology Undergraduate Education (NUE) in Engineering program at Florida A&M University (FAMU)-Florida State University (FSU) entitled "NUE: NanoCORE II (Nanotechnology Concepts, Opportunities, Research and Education)at the FAMU-FSU College of Engineering", under the direction of Dr. Ongi Englander, is designed to introduce aspects of nanoscale science and engineering into the core undergraduate curriculum. The NanoCORE II program will infuse and integrate nanoscale science and engineering (NSE) as a permanent component of the undergrduate curriculum, present multiple opportunities for undergraduate learning of concepts in NSE and create opportunities for undergraduates to pursue nanotechology related research activities. The NanoCORE II program builds upon the existing NUE NanoCORE program which has made a noteworthy impact on FAMU-FSU undergraduate educational content and experience since its inception in early 2009.

The broader impact of the NanoCORE II program includes the engagement and training of undergraduate students, and particularly those from traditionally under-represented groups in areas of great technological importance. Course materials developed through this project will be made widely available through web resources and presented to the local community through outreach activities. In particular, introductory nanotechnology material designed to target a wide audience will be disseminated at the National High Magnetic Field Laboratory (NHMFL) annual open house, at a Saturday children's program at a local museum, and through lectures and demonstrations presented to Tallahassee Community College, WIMSE (Women in Math, Science and Engineering) and FGAMP (Florida-Georgia Alliance for Minority Participation) college students.

NON-TECHNICAL SUMMARY:

Most commercial polymers are processed into useful materials by cooling them from a high temperature. During this process, a fraction of the long polymer molecules self-assemble in ordered crystalline regions connected by regions where the molecules remain disordered. The speed of the solidification process depends on the liquid phase structure of the melt and the entanglements (topology) that long polymer molecules adopt during heating. Molecules that retain memory of the ordered state in the melt act as seeds to speed up the crystallization. This project addresses how the seeded melt structure changes in polymers with short or long branches, or with polar or non-polar branches and their role on crystallization. Studies of model blends, and polyethylenes with pendant groups, either random or at a precise distance will enable building of fundamental relations between molecular structure and properties to predict the behavior of commercial complex polyethylene materials. These studies are significant also because the great expansion of shale gas extraction has placed the US as a very highly competitive provider of derivatives such as polyethylenes. Hence, advances in the understanding of the state of the melt and the crystallization of polyethylenes are of major relevance as they could lead to improved processing technologies and to reduced costs and energy utilization. The proposed research is also aimed at providing learning and training opportunities for graduate and undergraduate students, many of them underrepresented minorities.


TECHNICAL SUMMARY:

The proposed research program builds on recent developments on the strong melt memory of crystallization of random ethylene copolymers, and the unique layered crystallization of precision halogen substituted polyethylenes to further address the role of chain structure in the evolution and final crystal morphology of semicrystalline polymers with various types of short and long-chain branching. Models for random copolymers will be used to address: (a) the effect of branch length (ethyl to hexyl), chain architecture (stars, H-type, comb, pom-pom), and branch polarity (acetoxy) on melt diffusion, and self-nucleation; (b) the effect of comonomer content distribution on co-crystallization in model blends, and the interplay between sequence segregation and LLPS; (c) the generality of the role of sequence selection in crystalline melt memory. A second thrust aims to advance understanding of the evolution of the crystalline state of polyethylenes with pendant groups placed at the same equidistant length along the backbone. Taking advantage of model systems with pendant groups with controlled tacticity, the origin and drive for the formation of lamellar crystallites from isotactic as well as from atactic systems will be sought. Differences in sublamellar structure, and crystallization kinetics are of special interest as they relate to novel crystallites formed from ethylene-like copolymers with controlled tacticity that are not accessible in classical random ethylene copolymers. Molecular details at the crystal growth front will be extracted from the unique temperature gradient of growth rate kinetics.