Research Experiences for Undergraduates

The Triangle MRSEC is studying programmed assembly of soft matter, inventing materials that have never before existed and creating ways to use those materials.

When to Apply

Applications for 2012 closed at 5pm EST on Friday March 23, 2012. Check back in early 2013.

Before you apply you will need to:

• Prepare your resume
• Write a one page double spaced essay answering the question: Why are you interested in an REU in soft matter?
• Review the projects below, you will be asked to select your top three

After you apply you will need to:

• Email or send by postal mail your current transcript to the address below
• Have two recommendations sent to us (download instructions to give to your references)
• All materials must be recieved by March 23rd.

Recommendations and transcript should be sent to Elaine Fulton:

• Either email them to her at: mrsec@duke.edu or
• Triangle MRSEC
  Attn: Elaine Fulton
  Duke University
  Box 90271
  Durham, NC 27708

Stipend Includes

• 9 weeks housing on Duke's or North Carolina State University's campus
• $4200 stipend
• Up to $400 towards travel costs

Equal Opportunity Statement

Duke University and Duke University Health System are committed to affirmative action and fair employment. Whether in the classroom, the clinic, or elsewhere on or off campus, we believe in giving everyone the opportunity to succeed. Our commitment to principles of fairness and respect for all helps create a climate that is favorable to the free and open exchange of ideas and reinforces our knowledge that our differences are a source of strength, which help foster new opportunities in education, research, and patient care.

Eligibility

All applicants must be United States citizens or permanent residents and have health insurance coverage. Students entering their junior or senior year will be given preference, but exceptional entering sophomores will be considered.

Relevant Dates

• Students arrive: May 27-28
• Orientation: May 29
• Duke ends: July 28
• NC State ends: August 1

Research Opportunities for 2012

Soft Actuators

Professor: Michael Dickey, North Carolina State University
Key background knowledge needed: Students with a chemical engineering or chemistry background are preferred

The goal of this project is to construct and study soft actuators. Soft actuators are materials that move in response to a stimulus such as voltage, pressure, pH, or exposure to chemicals, and that have mechanical properties that are soft. Nature abounds with examples of soft actuators including muscle, squid, octopi, and certain insects. The project, which can evolve in several ways depending on student interest, will benefit from someone who is enthusiastic and creative. We envision the soft actuators being created by combining elastomeric polymers with a moldable liquid metal. The metal will be used to create soft electrodes that can apply electric fields to enable new modes of deformation. The work will be highly collaborative within the Dickey research group and with the group of Assistant Professor Xuanhe Zhao at Duke. The Dickey group studies soft materials, thin films, and interfaces and is interested in patterning, microfabrication, and soft / stretchable electronics.

Magnetoacoustic Assembly of Crystalline Colloidal Alloys

Professor: Ben Yellen, Duke University

An emerging class of artificially engineered materials called metamaterials displays physical and chemical functionality that depend not only on the individual properties of the smallest indivisible components within the material--the atoms--but also on their relative spatial organization, or  crystallinity. Self-assembly of the most well studied single-component colloidal systems are limited in the sense that only a few types of crystal structures (mostly fcc lattice) can be produced, which limits the accessible range of material properties. In order to achieve greater structural diversity and higher control over the material properties, self-assembly of "colloidal alloys" are currently being explored as a means for tuning the optical and mechanical properties of artificial materials. This research project will focus on magnetic field directed self-assembly, which has significant advantages over other techniques not only because it is possible to program the particle interactions by adjusting the particle type, but also because it is possible to anneal the assembled structures by adjusting the external field strength (in effect, by turning off the interactions to induce melting of the assembled structures). As a result, external field driven self-assembly offers a unique niche for programming the assembly of large, high-quality colloidal crystalline alloys. In this REU research project, an undergraduate student will have the chance to conduct "hands on" experiments on assembly of unique and strikingly beautiful colloidal crystalline alloys. The ultimate goal of the summer research project is to construct a phase diagram that shows which type of crystal will form as a function of the relative particle concentrations and their relative dipole moments. REU students will become familiar with the fields of electromagnetic field theory, colloids and surface science, as well as fundamental materials science. The scientific tools that will be used in this project include optical microscopy, confocal microscopy, wet chemical cleanroom techniques, image analysis, and some computation.

Computational and Theoretical Study of Colloidal Assembly

Professor: Patrick Charbonneau, Duke University
Key background knowledge needed: one year of physical chemistry (for chemists)/thermal physics (for physicists), or equivalent, and (ideally) some computer programming experience.

The relationship between the properties of a bulk material and its underlying microstructure underlies a quest for materials with ever greater structural diversity. Obtaining such a diversity can, however, be quite challenging. “Bottom up” colloidal self-assembly techniques are an attractive way to produce structural diversity. Colloidal building blocks are relatively cheap and are of the appropriate size (10nm – 10um) for building functionality in the infrared and visible wavelengths. Additionally, their interaction can be tailored to spontaneously assemble into a variety of structures. However, identifying the relevant parameters for controlling the assembly can be quite challenging. Fortunately, the computational and theoretical tools necessary to address this problem for a family of systems are now fairly efficient and accurate. This project will allow an undergraduate researcher to gain experience in computational and theoretical materials studies, and to compare the research results with the experimental work conducted in the Yellen lab.

Deposition of Thin Nanocoatings from Janus Particles for Photonic and Energy Applications

Professor: Orlin D. Velev, North Carolina State University

The deposition of thin nanoparticle coatings can improve the performance of solar cells, “smart” windows, heat-dissipating films and other functional nanomaterials. This REU project will use a technique for simple and efficient convective assembly of nanocoatings for the deposition of a new class of special Janus particles. These particles will have one metallic and one polymer side and thus will possess interesting optical and conductance properties. By depositing them in nanocoatings we will use the unusual properties of the Janus particles in new types of materials and devices that can change color, reflectance, heat and electrical conductance on demand. Key background knowledge needed: This is an experimental project, which will require some laboratory expertise, good communication skills and ability to work with a diverse group of graduate students and postdoctoral fellows.

Theory and Computer Simulation of Block Syntactomer Micellization

Professor: Michael Rubinstein, University of North Carolina at Chapel Hill

This project will focus on self-assembly of block copolymers into micells through computer simulations and scaling theories. The effect of amino-acid sequence on self-assembly will be represented by the key interaction parameters. The micellization temperature will be calculated as a function of these parameters as well as of the number of repeating "words in each block (the length of syntactomer). Key background knowledge needed: physics and mathematics. Helpful, although not required: computer programing skills, statistical thermodynamics, polymer physics.

Temperature-Triggered Micellization of ELP-DNA Block Copolymers

Professors: Stefan Zauscher & Ashutosh Chilkoti, Duke University

Many efforts have been made to advance new drug delivery system with optimal therapeutic activity while minimize negative side effect. Reversible micellar self-assembly of amphiphilic block copolymer system is becoming an increasingly interesting candidate as a drug delivery vehicle. Here we develop novel block copolymer systems that consist of a polypeptide block with thermally reversible phase transition (Tt), and a hydrophilic, single stranded polydeoxynucleotide (ssPDN) block. The polypeptide block also serves as a macroinitiator for the enzymatic growth of the ssPDN block, using a template-independent polymerase –terminal deoxynucleotidyl transferase (TdT). This REU project will focus on the characterization of the resulting diblock copolymers and their self assembly behavior as a function of block molecular weight and temperature. Students will work in a team environment and will be trained in relevant characterization techniques such as static light scattering, AFM imaging, and small angle X-ray scattering.

Molecular Dynamics Simulations of Polypeptides

Professor: Yara Yingling, North Carolina State University
Key background knowledge needed: peptide chemistry and protein structure and general knowledge of computer programs

Simulations can assist and accelerate the design of hierarchal supramolecular architectures by elucidating structure and dynamics of individual polypeptides, binding energies, kinetics and thermodynamic and by guiding the experimental procedures. Atomistic simulations, where all the atoms and interactions in the system are explicitly present, can provide insights into the sequence dependent molecular structure and dynamics, relative importance of electrostatics and hydrogen bonding, effect of solvent and temperature on the micellar and higher order assemblies. In this project, atomistic molecular dynamics simulations of syntactomers (peptides with repeating sequence of amino acids) will be used to predict and explain the effect of ionic strength, pH and the chain length on LCST value. Moreover, the temperature-dependent contributions to the stability of the polymer structures due to electrostatic, hydrogen bonding and van der Waals interactions will be analyzed and used as a guide for polypeptide sequence engineering.

Super Muscle: Graphene-Polymer Laminate Capable of Giant Actuation Stress and Strain

Professor: Xuanhe Zhao, Duke University

A graphene-polymer laminate recently created at the Duke Soft Active Materials Laboratory (SAMs Lab) is potentially capable of achieving unprecedented actuation stress and strain for dielectric polymers under voltages. Understanding the voltage-induced deformation, microstructure evolution, and instabilities of graphene-polymer systems is the focus of this project.

When an electric voltage is applied on the graphene-polymer laminate, it deforms by reducing its thickness and expanding its area. The laminate is named as super muscle, because its actuation stress and strain are much higher than those of human muscles. The super muscle has distinct advantages including compliant, lightweight, easy processing, noise free, fast response, and low cost over traditional metallic and ceramic transducers. The super muscle is a promising candidate to replace heavy motors to drive lightweight anthropomorphic prostheses, which will greatly improve the living quality of amputated population. In addition, full-page Braille displays actuated by super muscle are much more informative for blind people than the traditional single-line ones. In this project, we will understand the fundamental mechanics and physics behind super muscle, and explore its fascinating applications.

Tunable Nanoparticle-Elastomer Composites

Professor: Joe Tracy, North Carolina State University

The objective of this project is to create nanoparticle-elastomer composites, where coupling among the dispersed nanoparticles gives rise to mechanically-tunable optical or magnetic properties. These materials are potentially useful in strain sensors or actuators. A student working on this project will learn how to synthesize and characterize noble metal and/or magnetic nanoparticles, how to disperse them in elastomers, and how to measure the properties of the composites at variable strains. This project will utilize knowledge from organicc hemistry, introductory physics, and introductory materials science and engineering courses, but not all are required. This project will be performed in a wet chemistry laboratory, and previous experience from chemistry lab courses will be helpful. Students lacking some of this background but who are very interested in the topic may be selected; curiosity and a desire to learn interdisciplinary knowledge and skills are key prerequisites.

Synthesis of Silver-Coated Copper Nanowires and their Properties in Flexible, Transparent, Conducting Nanowire Networks

Professor: Ben Wiley, Duke University

The Wiley Lab has demonstrated that transparent conductors made from networks of copper nanowires are more flexible and affordable than indium tin oxide, the current transparent conductor of choice in mobile phones and solar cells. Problems with copper nanowires include their tendency to oxidize and their copper color, which makes them unsuitable for direct use in displays. In order to eliminate the copper color and make them more resistant to oxidation, we propose to coat the nanowires with a thin layer of silver. We would like an REU student to:

1. Determine the best way to uniformly deposit silver on the surface of the copper nanowires in solution by searching the literature and experimentally testing various methods.
2. Characterize the silver-coated nanowires using SEM, TEM, EDS, AAS, etc.
3. Test the properties of copper-silver nanowires in the context of transparent conducting films.

Self-Assembly of Elastin-like Polypeptides

Professor: Ashutosh Chilkoti, Duke University

The aim of this project is to explore the rules that govern the self-assembly of elastin-like polypeptides (ELPs) block copolymers that are fused to proteins. Understanding these rules will enable us to create nanoparticles for cancer targeted drug delivery that uniformly and multivalently display proteins for better cell uptake. ELPs are biopolymers composed of the pentapeptide repeat [Val-Pro-Gly-X-Gly] in which X can be any amino acid except proline. These biopolymers exhibit what is known as lower critical solution temperature (LCST) behavior in which they transition from extended chains to collapsed aggregates above a critical temperature. I am exploring the change in self-assembly into micelles of two ELP blocks that are hydrophilic and hydrophobic with respect to each other when the hydrophobic block undergoes its transition by fusing a protein genetically to the hydrophilic side of the two blocks. The student will help in synthesizing and characterizing the thermal profile of the hydrophobic ELP block.

Tailoring the Density of Grafted (Syntactomer) Peptides by Mechanical Deformation of Underlying Substrates

Professor: Jan Genzer, North Carolina State University

The purpose of this project is to develop a method for controlling the density of peptide molecules (i.e., syntactomers) on flexible silicone rubbers. The peptide molecules will be attached chemically to functional silicone networks featuring poly(vinylmethyl siloxane) (PVMS) via sequential coupling involving 1) thiol-ene attachment of carboxy-terminated thiols to the vinyl groups in PVMS and 2) standard peptide coupling protocols of peptides to the terminal –COOH groups. The density of peptides will be adjusted by mechanically deforming the PVMS network substrate (either before or after peptide attachment). For instance, when peptides are attached to a mechanically pre-stretched PVMS network, releasing the strain from the PVMS substrate after peptide coupling will increase the peptide grafting density. In contrast, when peptides are attached to an unstrained support, straining the PVMS substrate with grafted peptides will result in peptide assemblies with lower density than that of the original peptide array. The characteristics of the peptide assemblies will be studied by means of a battery of analytical methods available in the Genzer group. In addition, in collaboration with the Zauscher group at Duke University we will examine the in-plane organization of the peptide arrays via scanning probe microscopy. Key background knowledge needed: basic chemistry lab skills.

Programmed Self-Assembly of Biomacromolecules and Colloidal Particles on Polarized Ferroelectric Thin Films

Professors: Stefan Zauscher & Ben Yellen, Duke University

To date, control over surface charge is largely achieved by chemical patterning and setting the solution pH and ionic strength. These approaches lead to relatively low lateral resolution and surfaces of usually fixed charge. We are currently developing a new approach in which the surface charge density can be switched and controlled with tens of nanometer lateral resolution. Such surfaces have significant promise for detection and sensing applications as they should 1) enable control over the conformation of proteins and polymers at interfaces, 2) enable control over the hydrophobicity/hydrophilicity at the solid/liquid interface, 3) enable control over surface reactivity, and 4) enable the capture and release of drugs and other biological materials onto/from device surfaces. Our approach relies on the high surface charge density that can be achieved by imprinting local surface charge states into programmable ferroelectric thin films, such as lead zirconium titanate (PZT). This in turn can be harnessed for directing the localized self-assembly of biomacromolecules and colloidal particles on the surface. This research is materials science oriented and involves characterization by scanning electron microscopy (SEM), AFM, and ferroelectric capacitance measurements. The project also entails the nanoscale encoding of the polarization of the ferroelectric film locally using the AFM and subsequent characterization of the surface charge pattern and its interaction with proteins, organic molecules and colloidal particles in the immediate vicinity of the surface.

Synthesis and Characterization of Novel Smart Materials

Professor: Darlene Taylor, North Carolina Central University

For this project, a student will assist in the development and synthesis of smart polymers that respond to at least one external stimuli (i.e. pH, temperature, and electrical). Systematic variation in molecular architecture of these materials will be a key feature of this project. The resulting materials will be characterized by a variety of spectroscopic techniques including NMR, ESI, FTIR, LCMS, and DSC, MALDI, SEM, etc.

Acoustic Tractor Beams for Microparticle Manipulation and Assembly

Professor: Gabriel Lopez, Duke University

This project will investigate the use of acoustic forces for guiding and directing microparticles suspended in fluids for a variety of applications including acoustic-mediated assembly and biosensing of cells and proteins. Students participating in this project will take part in at least one, but preferably both, of the following two tasks. The first task aims to develop precise methods for surface modification of microparticles, so as to enable highly selective and specific interaction with other particles (e.g., glass, polymers or cells). These modifications will result in the formation of specific capture (bio)chemistries that can be used to form links between particles either before or during their manipulation and by acoustic fields. Fellows involved in this task will benefit from having coursework or research experience in organic chemistry and biochemistry. The second task aims to fabricate and optimize microfluidic systems that incorporate acoustic transducers and to further characterize the performance of these systems in the acoustic manipulation and assembly of microparticles. Hybrid fabrication methods will include traditional photolithography, silicon micromachining and replica molding. Fellows involved in this task will benefit from having coursework or research experience in materials science, fabrication techniques, fluid mechanics and finite element simulation.

Functional Petrification of Self-Assembled Nanomaterials

Professor: Gabriel Lopez, Duke University

Self-assembled supramolecular structures have shown great promise as drug delivery vehicles and components of biosensing devices, both in lab and in the clinic. These structures are successful because their amphiphilic constituents, such as phospholipids and peptides, spontaneously assemble though hydrophobic interactions into ordered structures that can easily incorporate desired functional components (e.g., targeting ligands). However, these assemblies are not covalently bound and thus unstable. Silica encapsulation has been shown to increase functional stability of a multitude of structures, including enzymes and whole cells. Our lab is developing precise methods of silica deposition onto self-assembled biomimetic materials with a high degree of control over silica structure (e.g., porosity and thickness). We aim to stabilize these assemblies to maintain suitable transport kinetics necessary for optimal function. The goal of the REU student would be to learn and apply sol-gel processes in design and synthesis of hybrid nano- and micro-particles.