Brian C. Benicewicz's research while affiliated with University of South Carolina and other places
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Publications (253)
Polyamide composite (PA-TFC) membranes are the state-of-the-art ubiquitous platforms to desalinate water at scale. We have developed a novel, transformative platform where the performance of such membranes is significantly and controllably improved by depositing thin films of polymethylacrylate [PMA] grafted silica nanoparticles (PGNPs) through the...
![Figure 1. PMMA calibration curve in CDCl 3 [6 mg/mL]. Non-linear and...](profile/Eric-Ruzicka-2/publication/370559533/figure/fig1/AS:11431281157193812@1683729022250/PMMA-calibration-curve-in-CDCl-3-6-mg-mL-Non-linear-and-irreproducible-data-is_Q320.jpg)
![Figure 2. PMMA calibration curve in Benzene-d6 [0.5 mg/mL] at...](profile/Eric-Ruzicka-2/publication/370559533/figure/fig2/AS:11431281157193814@1683729022476/PMMA-calibration-curve-in-Benzene-d6-05-mg-mL-at-sufficiently-dilute-conditions_Q320.jpg)
Diffusion-ordered spectroscopy (DOSY) 1H nuclear magnetic resonance (1H NMR) has become a powerful tool to characterize the molecular weights of polymers. Compared to common characterization techniques, such as size exclusion chromatography (SEC), DOSY is faster, uses less solvent, and does not require a purified polymer sample. Poly(methyl methacr...
Knowing the dielectric properties of the interfacial region in polymer nanocomposites is critical to predicting and controlling dielectric properties. They are, however, difficult to characterize due to their nanoscale dimensions. Electrostatic force microscopy (EFM) provides a pathway to local dielectric property measurements, but extracting local...
We systematically vary the nanoparticle (NP) dispersion state in composites formed by mixing polyisoprene homopolymers with polyisoprene grafted silica particles, and demonstrate how creep measurements allow us to overcome the limitations of small amplitude oscillatory shear (SAOS) experiments. This allows us to access nearly 13 orders in time in t...
Chlorine (Cl 2 ) is a fundamental feedstock material for the chemical industry, and chlorine-derived products contribute more than $46 billion to the US economy annually. Chlorine plays a major role in many applications such as clean drinking water, pharmaceuticals, and crop protection chemicals. Most chlorine is produced from electrolysis of brine...
Polymer-grafted nanoparticle (GNP) membranes show unexpected gas transport enhancements relative to the neat polymer, with a maximum as a function of graft molecular weight (MWg ≈ 100 kDa) for sufficiently high grafting densities. The structural origins of this behavior are unclear. Simulations suggest that polymer segments are stretched near the n...
We demonstrate for the first time a fully anhydrous gas-phase hydrogen chloride electrolyzer. By taking advantage of polybenzimidazole's (PBI) low membrane resistivity in anhydrous conditions (0.87 ± 0.57 Ω-cm2 at 160 °C) and its temperature and acid environment stability, we are able to directly convert pure hydrogen chloride gas to dry hydrogen a...
Brillouin light spectroscopy is used to measure the elastic moduli of spherical polymer-grafted nanoparticle (GNP) melts as a function of chain length at fixed grafting density (0.47 chains/nm^{2}) and nanoparticle radius (8 nm). While the moduli follow a rule of mixtures (Wood's law) for long chains, they display enhanced elasticity and anomalous...
Polymer brushes synthesized via reversible addition‐fragmentation chain transfer (RAFT) polymerization have undergone prolific study since our 2008 entry in this publication. Since then, elegant control of brush parameters including brush length, graft density, and brush composition has become a routine. Recent developments in the preparation of ch...
Previous work by the some of us has demonstrated enhanced electrochemical performance of polybenzimidazole (PBI) membranes with high phosphoric acid content prepared by the so-called PPA process. ¹ Methods of PBI synthesis that involve casting from an organic solvent cannot incorporate the more rigid PBIs characteristic of the PPA process due to th...
Fluxes of the four vanadium cations V ²⁺ , V ³⁺ , VO ²⁺ and VO 2 ⁺ through three archetypal membranes were measured as functions of current density. The membranes include a cation-exchange membrane, an anion-exchange membrane, and an initially uncharged membrane. Comprehensive data sets including mass and vanadium sorption, in-plane and through-pla...
Chlorine (Cl 2 ) is an important feedstock used in a variety of industry processes [1]. Hydrogen (H 2 ) and chlorine gas (Cl 2 ) can be produced by the electrochemical oxidation of hydrogen chloride (HCl) anhydrous gas. Previously, a gas phase hydrogen bromine (HBr) electrolyzer showed better performance than aqueous phase due to a significant incr...
Polymer membranes are critical to many sustainability applications that require the size-based separation of gas mixtures. Despite their ubiquity, there is a continuing need to selectively affect the transport of different mixture components while enhancing mechanical strength and hindering aging. Polymer-grafted nanoparticles (GNPs) have recently...
Recent advances in surface-initiated polymerization have given rise to a range of brush nanocomposites and hybrid functional materials. However, the synthesis of pure polyolefin-grafted nanocomposites by surface-initiated ring-opening metathesis polymerization (SI-ROMP) is a significant challenge due to the particle aggregation and irreversible par...
Objectives
The aim of this study was to examine how the concentrated delivery of less-effective antibiotics, such as the β-lactam penicillin-G, by linkage to nanoparticles (NPs) could influence the killing efficiency against various pathogenic bacteria including methicillin-resistant-Staphylococcus aureus (MRSA) and other multi-drug resistant (MDR)...
The field of polymer membrane design is primarily based on empirical observation, which limits discovery of new materials optimized for separating a given gas pair. Instead of relying on exhaustive experimental investigations, we trained a machine learning (ML) algorithm, using a topological, path-based hash of the polymer repeating unit. We used a...
High polymer content phosphoric acid (PA)-doped meta-para (m/p) polybenzimidazole (PBI) copolymer membrane was prepared via the poly(phosphoric acid) (PPA) process. This m/p-PBI copolymer membrane exhibited a much higher polymer solids content of 17 wt%, leading to the significantly improved creep resistance (1.9 × 10⁻⁶ Pa⁻¹) compared to the homopo...
Various phosphoric acid (PA)-doped polybenzimidazole (PBI) membranes, para-PBI, m/p-PBI, and meta-PBI, were prepared via the poly(phosphoric acid) (PPA) process. These three membranes showed high levels of PA (10-32 PA/PBI repeat unit(r.u.)) and proton conductivity (0.14-0.26 S/cm at 180oC) as compared with a conventionally imbibed meta-PBI membran...
Flexible energy storage devices with high energy density and long lifespan are in great demand for wearable and stretchable electronics. Herein, we report a flexible Zn-ion battery comprised of atomic layer deposited V2O5/C cathode, electrodeposited Zn/stainless-steel mesh anode, and para-polybenzimidazole (p-PBI)-based quasi-solid-state electrolyt...
Reversible addition‐fragmentation chain transfer (RAFT) polymerization of 2,3‐dimethyl‐1,3‐butadiene (DMB) in solution and on the surface of silica nanoparticles was investigated and PDMB‐grafted silica nanoparticles (PDMB‐g‐SiO2 NPs) with different chain densities and molecular weights were prepared. The kinetic studies of DMB polymerization media...
To meet the rising energy demand and efficiently utilize a larger amount of waste heat energy from various devices and systems, here we report an innovative thermo-electrochemical converter which utilizes the electrochemical potential of a hydrogen pressure differential applied across a proton conductive membrane. The amount of energy available to...
We previously showed that nanoparticles (NPs) could be ordered into structures by using the growth rate of polymer crystals as the control variable. In particular, for slow enough spherulitic growth fronts, the NPs grafted with amorphous polymer chains are selectively moved into the interlamellar, interfibrillar, and interspherulitic zones of a lam...
The tracer diffusion coefficient of six different permanent gases in polymer-grafted nanoparticle (GNP) membranes, i.e., neat GNP constructs with no solvent, show a maximum as a function of the grafted chain length at fixed grafting density. This trend is reproduced for two different NP sizes and three different polymer chemistries. We postulate th...
![Figure 2. TEM images of PI-RAFT-SiO 2 in (A#) PI-RAFT [matched] matrix...](profile/Zaid-Abbas-2/publication/336228335/figure/fig1/AS:974789825003525@1609419413770/TEM-images-of-PI-RAFT-SiO-2-in-A-PI-RAFT-matched-matrix-and-in-B-PI-Sigma_Q320.jpg)
![Figure 3. SAXS of PI-RAFT-SiO 2 in (A) PI-RAFT [matched] matrix and in...](profile/Zaid-Abbas-2/publication/336228335/figure/fig2/AS:974789833416704@1609419415098/SAXS-of-PI-RAFT-SiO-2-in-A-PI-RAFT-matched-matrix-and-in-B-PI-Sigma-mismatched_Q320.jpg)
We investigate the crystallization-induced ordering of C18 grafted 14 nm diameter spherical silica nanoparticles (NPs) in a short chain (Mw = 4 kDa, ĐM ≈ 2.3) polyethylene and a commercial high-density polyethylene (Mw = 152 kDa, ĐM ≈ 3.2) matrix. For slow isothermal crystallization of the low molecular weight matrix, the NPs segregate into the int...
Polymer-grafted nanoparticle (GNP) membranes show increased gas permeability relative to pure polymer analogs, with this effect evidently tunable through systematic variations in the grafted polymer chain length and grafting density. Additionally, these materials show less deleterious aging effects relative to the pure polymer. To better understand...
Polyethylene and nanosilica represent the most ubiquitous commodity plastic and nanocomposite filler, respectively. Despite their potential utility, few examples exist in the literature of successfully combining these two materials to form polyethylene nanocomposites. Synthesizing well-defined polyethylene grafted to a surface is a significant chal...
A series of high polymer content phosphoric acid doped meta/para (m/p) polybenzimidazole (PBI) copolymer membranes were prepared via the Polyphosphoric acid (PPA) Process. These copolymer membranes showed much higher solubility in solution (7-10 wt%) compared to the homopolymer para-PBI (typically < 3.5 wt%) which translated to higher polymer solid...
Polymer nanocomposites have improved mechanical, optical and thermal properties compared to traditional thermoplastics. To study the impact of grafted brush–matrix interactions on the mechanical properties of nanoparticle filled polymers, uniaxial tensile testing with digital image correlation (DIC) was done on polystyrene (PS) grafted SiO2 in low...
After approximately 15 years of development, polybenzimidazole (PBI) chemistries and the concomitant manufacturing processes have evolved into commercially produced membrane electrode assemblies (MEAs). PBI MEAs can operate reliably without complex water humidification hardware and are able to run at elevated temperatures of 120-180 OC due to the p...
Sulfonated polybenzimidazole (s-PBI) gel membranes were prepared and shown to have a high stability in concentrated sulfuric acid and strongly oxidizing vanadium (V) solutions. These membranes were considered candidates for use in vanadium redox flow batteries, and compared to the commonly used “conventionally imbibed” meta-polybenzimidazole (m-PBI...
This study addresses the colloidal stability of polymer-coated core/shell CdSe/CdxZn1−xS quantum dots (QDs) in the presence of L-glutathione under neutral conditions by means of photoluminescence (PL) and absorption spectroscopy. A reversible addition-fragmentation chain transfer-mediated synthesis was employed to produce copolymer ligands with dif...
Membranes made purely from nanoparticles (NPs) grafted with polymer chains show increased gas permeability relative to the analogous neat polymer films, with this effect apparently being tunable with systematic variations in polymer graft density and molecular weight. To explore the structural origins of these unusual transport results, we use smal...
Direct water electrolysis is commercially viable but too inefficient for large-scale hydrogen production. Hence the interest in using thermochemical cycles for producing hydrogen from renewable energy [1]. Thermochemical cycles produce hydrogen through a series of chemical reactions that result in the splitting of water at much lower temperatures (...
![Figure 1. An approximately linear relationship between ln([M 0 ]/[M t...](publication/326560403/figure/fig7/AS:668477564137477@1536388879304/An-approximately-linear-relationship-between-lnM-0-M-t-and-time-indicates-a_Q320.jpg)
The use of anion-exchange resins to separate and purify plutonium from various sources represents a major bottleneck in the throughput that can be achieved when this step is part of a larger separation scheme. Slow sorption kinetics and broad elution profiles necessitate long contact times with the resin, and the recovered Pu is relatively dilute,...
Polymer Electrolyte Membrane Fuel Cells (PEMFCs) face numerous challenges, involving the membrane nature and the active material for the cathodic reaction. A way to achieve more efficient PEMFCs is to increase their operating temperature above 373 K: High-Temperature PEMFCs (HT-PEMFCs). In this communication, we introduce for the first time the use...
After approximately 15 years of development, polybenzimidazole (PBI) chemistries and the concomitant manufacturing processes have evolved into commercially produced membrane electrode assemblies (MEAs). PBI MEAs can operate reliably without complex water humidification hardware and are able to run at elevated temperatures of 120-180 OC due to the p...
Liquid crystal polymers (LCPs) have become an important class of materials over the last 20 years. Numerous studies have been devoted to understanding their synthesis, structure, morphology, and properties. 1, 2 These advances have allowed liquid crystal polymers to become commercially important materials due to their high-strength, high-modulus, a...
We demonstrate the formulation of frequency-dependent dielectric permittivity by superposition of Debye functions inspired by viscoelastic relaxation theory. With multiple relaxation times and permittivity strength, a viscoelastic Prony Series is adapted to construct an expression of dielectric permittivity for polymer dielectric materials, which c...
RAFT polymerization and surface-initiated RAFT polymerization (SI-RAFT) of chloroprene was studied. The SI-RAFT polymerization rate of chloroprene was found to be slower than free solution RAFT polymerization, and further regulated by the graft density of grafted polymers. The resulting polychloroprene-grafted silica nanoparticles were directly cro...
Polymer nanocomposites with polymer grafted nanoparticles (NPs) are of great interest since they have improved properties relative to their unfilled analogs. While it is well-appreciated that nanocomposite flow behavior is critically affected by filler dispersion, the roles of the matrix and the polymeric grafts remain unexplored. We perform linear...
Polymer-based membranes play a key role in several industrially important gas separation technologies, e.g., removing CO2 from natural gas, with enormous economic and environmental impact. Here, we develop a novel hybrid membrane construct comprised entirely of nanoparticles grafted with polymers. These membranes are shown to have broadly tunable s...
Polybenzimidazole (PBI) polymers are excellent candidates for PEM fuel cell membranes capable of operating up to 200˚C. Several years ago, we developed a sol-gel process to produce PBI membranes loaded with high levels of phosphoric acid. This process, termed the PPA process, uses polyphosphoric acid as the condensing agent for the polymerization a...
The preparation of well-defined block copolymers using controlled radical polymerization depends on the proper order of monomer addition. The reversed order of monomer addition results in a mixture of block copolymer and homopolymer and thus has typically been avoided. In this paper, the low blocking efficiency of reversed monomer addition order is...
One-dimensional photonic crystals can be formed by self-assembly of block copolymers. However, such materials are still difficult to make due to the synthetic challenge of making high molecular weight block copolymers and the slow self-assembly characteristics of these block copolymers to form high domain spacings (d >150 nm). Herein we report a ne...
A pH and thermal dual-responsive nanocarrier with silica as the core and block copolymer composed of poly(methacrylic acid) (PMAA) and poly(N-isopropylacrylamide) (PNIPAM) as the shell was prepared by surface-initiated reversible addition–fragmentation chain-transfer (SI-RAFT) polymerization. The resulting SiO2-PMAA-b-PNIPAM particles dispersed ind...
While ∼75% of commercially utilized polymers are semicrystalline, the generally low mechanical modulus of these materials, especially for those possessing a glass transition temperature below room temperature, restricts their use for structural applications. Our focus in this paper is to address this deficiency through the controlled, multiscale as...
The separation of hazardous metals from contaminated sources is commonly achieved with ion-exchange resins. The resins have a high surface area decorated with many ion-exchange sites and thus a high sorption capacity for the analyte of interest. However, these sites are primarily accessed by diffusion which limits the throughput and quality of the...
The hybrid sulfur thermochemical cycle has seen much attention recently due to its potential to enable the production of clean hydrogen on a large scale with a higher energy efficiency than water electrolysis. The two step hybrid sulfur (HyS) process involves the high temperature decomposition of sulfuric acid to produce sulfur dioxide, oxygen, and...
Polybenzimidazoles (PBIs) are attractive membrane materials for H2/CO2 separation at hydrocarbon fuel derived synthesis gas operating conditions due to their exceptional physicochemical stability and promising permselectivity character. PBI molecular structure modification is a viable approach to disrupt chain packing altering the free-volume archi...
Incorporating inorganic nanoparticles (NPs) into polymer matrices provides a promising solution for suppressing space charge effects that can lead to premature failure of electrical insulation used in high voltage direct current engineering. However, realizing homogeneous NP dispersion is a great challenge especially in high-molecular-weight polyme...
In this study, PBI-based block copolymers were developed and their performance as membranes in high temperature polymer electrolyte membrane fuel cells was evaluated. This type of block copolymer consists of “phosphophilic” PBI and “phosphophobic” non-PBI segments. The final properties of such block copolymers strongly depended on the length of the...
Adding nano-sized fillers to epoxy has proven to be an effective method for improving dielectric breakdown strength (DBS). Evidence suggests that dispersion state, as well as chemistry at the filler-matrix interface can play a crucial role in property enhancement. Herein we investigate the contribution of both filler dispersion and surface chemistr...
The preparation of well-defined polyisoprene-grafted silica nanoparticles (PIP-g-SiO2 NPs) was investigated. Surface initiated reversible addition fragmentation chain transfer (SI-RAFT) polymerization was used to polymerize isoprene from the surface of 15 nm silica NPs. A high temperature stable trithiocarbonate RAFT agent was anchored onto the sur...
Surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization has been widely used to synthesize various polymers grafted from nanoparticles (NPs) for incorporation into polymer nanocomposites. It is believed that these grafted polymer brushes, with a similar chemistry as the matrix polymer, can be employed to improve...
The field of polymer nanocomposites has been at the forefront of research in the polymer community for the past few decades. Foundational work published in Macromolecules during this time has emphasized the physics and chemistry of the inclusion of nanofillers; remarkable early developments suggested that these materials would create a revolution i...
The hybrid sulfur cycle has been investigated as a means to produce CO2-free hydrogen efficiently on a large scale through the decomposition of H2SO4 to SO2, O2, and H2O, and then electrochemically oxidizing SO2 back to H2SO4 with the cogeneration of H2. The net effect is the production of hydrogen and oxygen from water. Recently, sulfonated polybe...
In this article, we report the synthesis of a new bimodal surface ligand morphology on silica nanoparticles. Combining grafting-to and grafting-from approaches, in this study, we demonstrated the efficacy of anthracene surface modification for improving the dielectric breakdown strength (DBS) under alternating-current and direct-current conditions...
The hybrid sulfur thermochemical cycle has seen much attentional recently due to its potential to enable the production of clean hydrogen on a large scale with a higher efficiency than water electrolysis.[1-9] The two step hybrid sulfur (HyS) process involves the high temperature decomposition of sulfuric acid to produce sulfur dioxide, oxygen, and...