Research Theme: Self and Directed Assembly of Colloids

Dielectrophoretic Assembly of P3HT Colloids for Electronic Films

The objectives of this research project are to investigate a novel dielectrophoresis (DEP)
technique to manufacture hierarchically ordered conjugated polymer films from colloidal suspension and to create a new processing paradigm for organic electronics applications. This research will provide a new nanomanufacturing method for directed assembly of multicomponent nanoparticles into well-defined structured thin films over a range of length scales. Specifically we have investigated a novel DEP technique for hierarchical patterned deposition of colloidal nanoparticles of semiconducting polymers, and have elucidated the role of polymer nanoparticle preparation variables on particle size, colloidal stability and internal polymer chain structures, and characterized the relationship between this new nanomanufacturing paradigm and polymer film morphology and electronic properties. By controlling the morphology of conjugated polymer thin films, our hypothesis is that we will obtain films from aqueous colloidal nanoparticle assembles suitable for devices with improved electronic properties compared to films prepared using conventional film-casting from organic solvents. This project is in collaboration with Prof. Margaret Sobkowicz-Kline at UML.

Publications:

“Controlling the Particle Size of Aqueous Conjugated Polymer Colloids and Impact on Transistor Performance”, H. Pan, B. Tan, A. Yazdani, B. M. Budhlall, M. J. Sobkowicz, Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2020, 594, 124633.
B. Tan, H. Pan, B. M. Budhlall, M. J. Sobkowicz, “Poly(3-hexylthiophene)/Poly(styrene) Blended Colloids: Exploiting the Effects of Composition and Marginal Solvent,” Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018, 539, pp. 221-228.
B. Tan, H. Pan, H. Li, M. Linus, B. M. Budhlall, M. J. Sobkowicz, “Improving Charge Carrier Mobility of Polymer Blend Field Effect Transistors with Majority Insulating Polymer Phase,” J. Phys. Chem. C, 2018, 122 (5), pp 2918–2930.

MONODISPERSED SWCNT FOR CHEMICAL SENSORS

In this project we apply the fundamental paradigm of materials science and engineering (structure-property-processing-performance) to hybrid hard (SWCNT) and soft materials (surfactants) at the nanometer length scale. This highly interdisciplinary project is enabled by a sophisticated suite of instrumentation including ultra-high vacuum (UHV) scanning tunneling microscopy (STM), and other equipment for studying the electrical and optical properties of materials. Ongoing research projects range from fundamental studies (e.g., zeta potential of monodispersed SWCNTs) to applied technology development (e.g., optimization of nanotubes for chemical sensor devices). This project is in collaboration with Prof. Carol Barry at UML.

Publication:

R. D. Devre, B. Budhlall, C. Barry, “Enhancing the Colloidal Stability and Electrical Conductivity of Single‐Walled Carbon Nanotubes Dispersed in Water”, Macromolecular Chemistry and Physics. 2016, 217 (5), 683-700.

Janus Colloids with Surface Anisotropy

A versatile new concept was developed for the synthesis of Janus colloids composed of Laponite nanoclay armored poly(styrene) colloids with an anisotropic surface potential via a double Pickering emulsion template. First, polystyrene or poly(divinylbenzene) colloids stabilized with Laponite nanoclay are synthesized via a Pickering miniemulsion approach. These nanoparticle-stabilized colloids were then templated at a wax-water interface in a second Pickering emulsion in order to chemically modify one hemisphere of the colloids. Janus modification of the colloids was accomplished by cation exchange of sodium ions, originally present on the surface of the Laponite with various salts of modifying ions (Ca(2+), Fe(2+), and Fe(3+)) in the suspension.

Publication:

N. Pardhy, B. M. Budhlall, “Pickering Emulsion as a Template to Synthesize Janus Colloids with Anisotropy in Surface Potential”, Langmuir, 2010, 26 (16), 13130–13141.

QUANTUM DOT ENCAPSULATED NANOCOLLOIDAL BIOPROBES

Bioimaging probes incorporating quantum dots (QDs) are important for identifying organelles and monitoring their movement/location in living cells. Organelle specificity can be accomplished by functionalizing probe surfaces with chemical groups that can react with antibodies capable of targeting specific organelle-protein epitopes. Here, such a bioprobe is generated by encapsulating ZnS-capped CdSe QDs within polystyrene (PS) nanocolloids via Pickering miniemulsion using laponite nanoclay platelets as solid-stabilizers. The encapsulation of QDs within the PS matrix proved to be advantageous as the PS-QD nanocolloids exhibited a slower rate of photobleaching when compared to free QDs. The PS-QD nanocolloids were found to have little or no impact on cell viability and were not toxic to NIH 3T3 cells, as determined by a standard cell viability and MTS cytotoxicity assay. Cell-imaging experiments of the PS-QD nanocolloids using confocal microscopy demonstrated their successful internalization into NIH 3T3 cells. Altogether, the present study confirms that the exceptional binding between Biotin and Streptavidin can be used to conjugate antibodies to PS-QD nanocolloids for in vitro imaging. This project is in collaboration with Prof. Peter Gaines at UML.

Publication:

S. Muralidhara, K. Malu, P. Gaines, B. M. Budhlall, “Quantum Dot Encapsulated Nanocolloidal Bioconjugates Function as Bioprobes for In Vitro Intracellular Imaging”, Colloids and Surfaces B: Biointerfaces, 2019, 182. 110348.

Research Theme: Biomedical Polymers

Antimicrobial and Antifouling Polymers

Infections pose serious concerns in a variety of settings, such as from medical implants, in hospitals, in water purification and in food packaging and storage. Hospital acquired infections are one of the leading causes of death in USA. In the United States alone, an estimated 100,000 deaths and $6.5 billion in cost is attributed to infections. The overuse of antibiotics has led to the development of drug resistant bacteria which are the primary cause of these infection related deaths. According to CDC, at least two million people are infected by drug resistant bacteria. Thus, novel approaches are urgently needed to treat these infections. Novel polymers containing quaternary functional groups, with and without PEG side chains were synthesized and characterized for their ability to selectively lyse the membranes of gram negative bacteria, E.coli mimics whilst not lysing those of a red-blood cell mimic.

Publications:

A. Garle, B. M. Budhlall, “PEG Bottle Brush Copolymers as Antimicrobial Mimics: Role of Entropic Templating in Membrane Lysis,” Langmuir, 2019, 35 (9), 3372-3382.
A. L. Garle, F. White, B. M. Budhlall, “Improving the Antifouling Properties of Polypropylene Surfaces by Melt Blending with Poly(ethylene glycol) Diblock Copolymers,” Journal of Applied Polymer Science, 2018, 135 (15), pp. 46122.

Research Theme: Smart Stimuli Responsive Polymers

LIGHT RESPONSIVE Shape Memory Polymers

The focus of this work is to synthesize semicrystalline poly(e-caprolactone) (PCL) copolymer networks with stimuli-responsive shape memory behavior. We are currently investigating a series of triblock copolymers with tunable shape memory transition temperatures, ranging from 54 C to close to body temperature. Our work establishes a general design concept for inducing a shape memory effect into any semicrystalline polyester network. More specifically, it can be applied to systems which have the highest transition temperature closest to the application temperature. An advantage of our novel copolymers is their ability to be cross-linked with UV radiation without any initiator or chemical cross-linker. Possible applications are envisioned in the area of endovascular treatment of ischemic stroke and cerebrovascular aneurysms, and for femoral stents.

Publications:

H. Xu and B. M. Budhlall, “Gold nanorods or nanospheres? Role of particle shape on tuning the shape memory effect of semicrystalline poly(ε-caprolactone) networks,” Royal Society of Chemistry (RSC) Advances, 2018, 8, pp. 29283-29294.
A. Garle, S. Kong, U. Ohja, B. Budhlall, “Thermoresponsive Semicrystalline Poly(caprolactone) Networks: Exploiting Crosslinking in Cinnamoly Moieties to Design Polymers with Tunable Shape Memory” ACS Applied Materials & Interfaces, 2012, 4 (2), 645-657.

Self-healing nanocomposites for impact mitigation

In this study, poly(urea formaldehyde) (PUF) nanocapsules with epoxy cores were blended into a polyurea matrix, formulated as poly[(phenyl isocyanate)-co-formaldehyde] (PMDI) (f = 3.4), and a diamine curing agent (VERSALINK 650) to form nanocomposites. The nanocomposites were then subjected to impact delamination tests at temperatures below −74 °C. Scanning electron microscopy was used to qualitatively inspect the nanocomposites before the impact (virgin), after the impact, and after self-healing.

Publication:

Y. Liu and B. M. Budhlall, “Self-healing Nanocomposites comprised of Poly(urea formaldehyde) Nanocapsules in a Thermosetting Polyurea”,
European Polymer Journal, 2020, 126, 109545.

TUNABLE Oxygen permeable liquid crystalline polymers

In this project we successfully synthesized a series of azobenzene containing side chain liquid crystalline polymers (azoLCPs) with different flexible spacer group lengths (C₅, C₈, C₉, C₁₀, C₁₂) and characterized the relationship between their switchable O₂ gas permeability properties and LC mesophase structures. Switching of O₂ gas permeability is accomplished by heating which corresponds to highly crystalline nematic phase to a less crystalline isotropic phase, in other-words a “closed” to “open” lattice spacing. Increasing the methylene spacer length had little or no effect on O₂ gas permeability properties however it did decrease the T_c, allowing fine control of the temperature at which the switch in O₂ gas permeability properties takes place by tuning the mesophase between nematic and isotropic states. Such an ability to tune O₂ gas permeability properties of the azoLCP-C_n film by an order of magnitude can have potential applications in “smart” textiles. It is envisioned that thermally responsive azoLCP films can be applied to textiles to achieve “smart” textile functionality, whereby the gas vapor permeability increases at higher temperatures (to promote cooling) and decreases at lower temperatures (to trap warm air) thereby protecting the wearer from dramatic temperature changes in the environment.

Publication:

S. Hassan, R. Anandakathir, M. Sobkowicz, B. Budhlall, “Tuning Oxygen Permeability in Azobenzene-containing Side-chain Liquid Crystalline Polymers” Polymer Chemistry. 2016, 7(7):1452-1460.

Core-Shell Microcapsules for Targeted, Controlled Delivery and Release

In this project we synthesized polymer colloids that can respond to stimuli by altering their properties or performing a desired task. We can do this through liquid-liquid interface driven assembly of colloidal building blocks and utilizing various heterogeneous polymerization strategies to fabricate a variety of microcapsules featuring multicore-crosslinked shell of poly(N-isopropylacryamide)(PNIPAm) particles. In this study, a multicore-shell structure was achieved through an oil/water/oil double emulsion method. We are interested in studying how these particles can be used for applications in encapsulation and delivery.

Publications:

T. Trongsatitkul, B. M. Budhlall, “Microgels or Microcapsules? Role of Morphology in the Drug Release Kinetics of Thermoresponsive PNIPAm-co-PEGMa Hydrogels”, Polymer Chemistry, 2013, 4, 1502-1516.
T. Trongsatitkul, B. M. Budhlall, “Temperature Dependence of Serum Protein Adsorption in Thermoresponsive PEGylated PNIPAm Microgels”, Colloids and Surfaces B: Biointerfaces, 2013, 103, 244– 252.
T. Trongsatitkul, B. M. Budhlall, “Multicore/Shell PNIPAm-co-PEGMa Microcapsules for Cell Encapsulation”, Langmuir, 2011, 27 (22), 13468–13480.

Research Theme: Sustainable Polymers

Arterial prototype model for biodegradation studies of polymers

There are currently no tests to determine degradation rates and characteristics of bioabsorbable materials that come in direct contact with blood. Blood follows a helical flow pattern and is momentum driven rather than pressure driven resulting in conditions not simulated in degradation tests. This is of concern to the degradation of stents because certain stent designs have the potential to liberate fragments large enough to induce strokes or other detrimental health concerns. A prototype designed to simulate in-vivo conditions including flow rates, pressures, temperatures, and flow characteristics was designed and built. This system was designed with a fast change testing chamber to allow sample removal and different configurations to simulate different sized arteries and conditions. The critical consideration for the testing chamber was the silicone artificial artery to simulate helical flow found in blood vessels. The effects of this flow pattern was compared to laminar and turbulent flow patterns and determined to best simulate actual body conditions. Degradation of polymers was characterized with weight loss of the sample, visual inspection via camera, and observations of liberated pieces running through meshes to indicate size.

Publication:

B. Chasse, H. Xu, B. M. Budhlall, “In-vitro biodegradation study of poly(ε-caprolactone) films using a 3D printed helical flow prototype to simulate the physiological conditions for cardiovascular implanted devices”, Biomedical Physics & Engineering Express, 2019, 5, 065021.

Green Synthesis of Biosurfactants

The goal of our research is to develop a new class of safer surfactants as a sustainable alternative to toxic Nonylphenol ethoxylates (NPEs). Although effective as cleaning agents, NPEs are bio-accumulative and degrade into more toxic and less biodegradable compounds that are known to be endocrine disruptors, threatening both aquatic and human life. While there are several partly bio-based alternatives for NPEs available commercially, their efficacy and bio-degradability are not well established. Therefore, there is an immediate need for non-toxic, bio-based alternatives (from renewable resources) that can be as effective as NPEs. This project is in collaboration with Prof. Ramaswamy Nagarajan.

Publication:

Z. F. Aris, R. M. Bouldin, M. G. Pelletier, P. C. Gaines, B. Budhlall, R. Nagarajan, “Microwave-assisted synthesis and characterization of hydrophilically functionalized polygalacturonic acid,” Carbohydrate Polymers. 2017, 155: pp. 432–439.

Research Theme: Nanoparticles

Nanomaterials and Nanofluids

Extensive scientific research and investments have been made in the field of nanotechnology, leading to high rate, high volume manufacturing of a variety of engineered nanomaterials (ENM). It has been estimated that the production of ENM would increase approximately 25 fold from a few thousand tons produced today to 58,000 tons by 2020 with possible applications in a range of diverse fields, from development of advanced materials, novel devices in the fields of medicine, biotechnology, energy, environmental remediation to their use in consumer products. In response to this reality, a broad consensus is being built to conduct adequate environmental, health and safety evaluations of these novel ENM at an early stage of materials/product development.

One of the objectives of this experimental study is to evaluate the effects of particle species, surface charge, concentration, preparation technique, and base fluid on thermal transport capability of nanoparticle suspensions (nanofluids). This project is in collaboration with Profs. Hongwei Sun, Majid Charmchi and Zhiyong Gu.

Another objective is to evaluate performance of an oxidative assay for measuring ENM-induced free radicals. A series of diverse and well-characterized ENM were tested in the assay. We investigated the effect of sonication conditions, dispersion media, ENM concentration, and the use of horseradish peroxidase (HRP) on the results. This project is in collaboration with Prof. Dhimiter Bello.

Publications:

A. K Pal, D. Bello, B. Budhlall, E. Rogers, D. K. Milton, “Screening for Oxidative Stress Elicited by Engineered Nanomaterials: Evaluation of Acellular DCFH Assay” Dose-Response, 2012, 10 (3), dose-response. 10-036. Pal.
R. Gowda, H. Sun, P. Wang, M. Charmchi, F. Gao, Z. Gu, B. Budhlall, “Effects of Particle Surface Charge, Species, Concentration, and Dispersion Method on the Thermal Conductivity of Nanofluids” Advances in Mechanical Engineering, 2010, (https://doi.org/10.1155/2010/807610).

Research Theme: Engineering Education

I am committed to teaching, mentoring and training the next generation of Plastics Engineers for leadership positions in Industry, Academia and Government. Several educational modules focused on bio-based polymers were successfully developed and implemented for undergraduate curricula. These modules included experiments for (1) synthesis of a biodegradable polymer, (2) characterizing the properties of this polymer and comparing these properties with those of a commonly-used petroleum-based polymer, and (3) melt processing a bio-based, biodegradable polymer. All modules were well-received by and produced significant learning by the undergraduate students.

Publications:

“Synthetic Resins and Plastics”, M. Sobkowicz, B. M. Budhlall, J. L. Mead, pp. 1397-1462. In Kent and Riegel’s Handbook of Industrial Chemistry and Biotechnology, (13th ed.), J.A. Kent, Ed., Springer, Germany, 2017.
C. Barry, B. Budhlall, R. Nagarajan, “Undergraduate Modules for Bio-Based Plastics”, Plastics Engineering, 2016, 72 (3), 30.
Z. Gu, B. Budhlall, H. Sun, C. Barry, A. Donatelli, J. Lohmeier, “A New Interdisciplinary Engineering Course on Nanoscale Transport Phenomena” American Society of Engineering Education (ASEE), 2013, 1.

Research Projects

Research Theme: Self and Directed Assembly of Colloids

Dielectrophoretic Assembly of P3HT Colloids for Electronic Films

MONODISPERSED SWCNT FOR CHEMICAL SENSORS

Janus Colloids with Surface Anisotropy

QUANTUM DOT ENCAPSULATED NANOCOLLOIDAL BIOPROBES

Research Theme: Biomedical Polymers

Antimicrobial and Antifouling Polymers

Research Theme: Smart Stimuli Responsive Polymers

LIGHT RESPONSIVE Shape Memory Polymers

Self-healing nanocomposites for impact mitigation

TUNABLE Oxygen permeable liquid crystalline polymers

Core-Shell Microcapsules for Targeted, Controlled Delivery and Release

Research Theme: Sustainable Polymers

Arterial prototype model for biodegradation studies of polymers

Green Synthesis of Biosurfactants

Research Theme: Nanoparticles

Nanomaterials and Nanofluids

Research Theme: Engineering Education