Roderick Pernites

Rice University, Houston, TX, United States

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Publications (26)114.59 Total impact

  • Macromolecular Materials and Engineering 09/2012; 297(9). · 2.34 Impact Factor
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    ABSTRACT: In this paper, we demonstrated for the first time the use of electrodeposited superhydrophobic conducting polythiophene coating to effectively protect the underlying steel substrate from corrosion attack: by first preventing water from being absorbed onto the coating, thus preventing the corrosive chemicals and corrosion products from diffusing through the coating, and second by causing an anodic shift in the corrosion potential as it galvanically couples to the metal substrate. Standard electrochemical measurements revealed the steel coated with antiwetting nanostructured polythiophene film, which was immersed in chloride solution of different pH and temperature for up to 7 days, is very well protected from corrosion evidenced by protection efficiency of greater than 95%. Fabrication of the dual properties superhydrophobic anticorrosion nanostructured conducting polymer coating follows a two-step coating procedure that is very simple and can be used to coat any metallic surface.
    ACS Applied Materials & Interfaces 06/2012; · 5.01 Impact Factor
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    ABSTRACT: An innovation to thin-film molecular imprinting is presented for the sensitive detection and effective discrimination of chiral compounds using a portable quartz crystal microbalance transduction technique. The facile approach involves i) colloidal sphere layering of latex particles onto the surface via a Langmuir-Blodgett-like technique followed by ii) template molecular imprinting using electrodeposition of a single functional and cross-linking monomer.
    Small 03/2012; 8(11):1669-74. · 7.82 Impact Factor
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    ABSTRACT: The highly selective and sensitive detection of a chemical nerve agent analog pinacolyl methylphosphonate (PMP) was demonstrated using an electrochemically molecularly imprinted polymer (MIP) polythiophene film onto a quartz crystal microbalance (QCM) transducer surface. The fabrication and optimization of the sensor film was monitored by in situ electrochemistry-QCM (EC-QCM) measurements, which determined the change in mass and simultaneous change in redox properties of the polymer film. The film deposition, template loading, and template removal were evidenced by a combination of surface characterization techniques such as the attenuated total reflection infrared spectroscopy and high-resolution X-ray photoelectron spectroscopy. The fabricated MIP film demonstrated a limit of detection and a limit of quantification of ∼60 and ∼197 μM, respectively. The linear sensing range is between 125 and 250 μM concentration of PMP. Finally, theoretical modeling (AM1 semiempirical quantum calculations) studies revealed that a stable prepolymerization complex is formed in solution with the existence of H-bonding interactions using the 2:1 monomer-to-template ratio. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
    Journal of Polymer Science Part A Polymer Chemistry 02/2012; 50(4):675-685. · 3.54 Impact Factor
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    ABSTRACT: The synthesis of double-layer-type dendrimers with carbazole and phenylazomethine as the dendron with a symmetric tetraphenylmethane core is reported. Structural modeling studies showed that the G3 dendrimer has a rigid and spherical structure. These dendrimers were thermally stable (Td10% over 500 °C) with the TGA-MS study revealing a degradation mechanism occurring first at the inner-layer phenylazomethine group. The metal (Lewis acid) complexation property of these dendrimers was also studied. Electrochemical measurements showed that these dendrimers have the appropriate HOMO level as a hole-transporting material with electropolymerizability on the peripheral carbazole groups. A photo-cross-linking property of the dendrimer film was also observed. Finally, electro-nanopatterning with conducting AFM and photopatterning of the dendrimer film were demonstrated. Thus, the new dendrimer is a potential hole-transporting material that is patternable through oxidation of the peripheral carbazole units by either photochemical or electrochemical methods.
    Macromolecules 02/2012; 45(3):1288-1295. · 5.93 Impact Factor
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    ABSTRACT: The electrografting of oligoethylene glycol or (OEG)ylated carbazole linear dendrons and their protein adsorption resistance properties have been investigated by surface plasmon resonance (SPR) spectroscopy. A series of the carbazole dendron generations, G0, G1, G2 were synthesized and electrodeposited by cyclic voltammetry (CV) on Au-glass substrate which also served as a surface for evanescent waveguide excitation in SPR. In addition, the films were characterized by in-situ electrochemical SPR (EC-SPR), static water contact angle, and X-ray photoelectron spectroscopy (XPS) measurements. It was observed that electropolymerized films prepared from the higher generation linear-dendron G2, is most effective in preventing non-specific protein adsorption as observed by SPR kinetic measurements using fibrinogen as model protein. Film thickness also played a critical role in protein adsorption resistance - electrodeposition approaching monolayer thickness gave the highest protein resistance. In addition, the films were evaluated for non-specific protein binding against the smaller proteins, lysozyme and bovine serum albumin (BSA). The study provides insight to manipulating the architecture and composition of protein resistant materials deposited on metals and semi-conducting substrates and their possible use in biomedical applications.
    Polymer. 01/2012; 53(2):427–437.
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    ABSTRACT: We report the fabrication of patterned binary polymer brushes via colloidal particle templating combined with electrodeposited ATRP, RAFT, and ROMPinitiators. From the hexagonally close-packed template and subsequent patterned arrays, surface-initiated polymerization (SIP) demonstrated novel non-lithographically and laterally patterned binary polymer brush composition.
    Soft Matter 12/2011; 8(2):353-359. · 4.15 Impact Factor
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    ABSTRACT: A molecularly imprinted polymer (MIP) film for dopamine (DP) sensing is fabricated from cathodically electrodeposited p-aminostyrene (PAS) on electrode surfaces in a surface plasmon resonance (SPR) spectroscopy setup. The monomer is more commonly used in monolithic MIP free-radical bulk polymerizations. The film growth and rebinding of DP are monitored by electrochemical-SPR (EC-SPR) spectroscopy. UV–Vis, IR spectroscopy, XPS, AFM, and electrochemistry methods are used to characterize the film. High selectivity against analogous analytes and up to picomolar detection of DP is demonstrated. The reusability of the sensor is also established. Theoretical modeling studies with AM1 calculations predict H-bonding in a stable prepolymerization complex in solution prior to MIP film formation.
    Macromolecular Chemistry and Physics 11/2011; 212(22). · 2.39 Impact Factor
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    ABSTRACT: The electrodeposition of polymer nanocomposite thin films of PVK–GO is demonstrated. Highly exfoliated and stable graphene oxide (GO) solutions are prepared by incorporating poly(N-vinylcarbazole) (PVK) through mixing. Enhanced stability up to 30 d is observed in both aqueous and organic solvents. TGA, XRD, FTIR, and UV-vis measurements confirm nanocomposite formation. CV enables electrodeposition of the films. The presence of GO on the PVK–GO surface is confirmed by the appearance of the C=O and OH stretching vibrations, attributed to the carboxylic and hydroxyl groups of GO. AFM measurements show homogeneous and well-defined film morphology.
    Macromolecular Chemistry and Physics 11/2011; 212(21). · 2.39 Impact Factor
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    ABSTRACT: Bisphenol A (BPA) sensing was investigated based on electrochemical impedance spectroscopy (EIS) measurements of an electropolymerized molecularly imprinted polymer (E-MIP) film. The E-MIP film is composed of varying ratios of BPA–terthiophene and carbazole monomer complex deposited onto indium tin oxide (ITO) substrates via anodic electropolymerization using cyclic voltammetry (CV). Subsequently, the interfacial properties of these films were studied using the non-Faradaic EIS technique. The same technique was then used to measure the presence of templated BPA which is a known endocrine disrupting chemical (EDC). Analyses of the EIS results were performed using equivalent circuits in order to model the electrical and impedance properties through the interface. A linear calibration curve was established in the range 0–12 mM concentrations of the analyte. Moreover, the selectivity of the films against bisphenol AF and diphenolic acid was demonstrated. The E-MIP sensor may have advantages in environmental monitoring of bisphenol A in aqueous analyte/pollutant samples.
    Macromolecules. 08/2011;
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    ABSTRACT: A facile approach of making scalable nanocomposite and electro-patterned films using graphene oxide (GO) and poly(N-vinylcarbazole) (PVK) is reported. The method involves the layering of polystyrene colloidal templates, electrodeposition of the composite film on template array, and finally removal of the sacrificial templates to reveal the patterned GO-PVK arrays.
    Chemical Communications 08/2011; 47(35):9810-2. · 6.38 Impact Factor
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    ABSTRACT: The facile preparation of poly (N-vinyl carbazole) (PVK) and multiwalled carbon nanotubes (MWNTs) solution and conjugated polymer network (CPN) nanocomposite film is described. The stable solutions of PVK/MWNT were prepared in mixed solvents by simple sonication method, which enabled successful deaggregation of the MWNTs with the polymer matrix. MWNT was most effectively dissolved in N-cyclohexyl-2-pyrrolidone (CHP) compared to other solvents like N-methyl pyrrolidone (NMP), dimethyl formamide, and dimethyl sulfoxide (DMSO). The composite solution was relatively stable for months with no observable precipitation of the MWNTs. Thermogravimmetric analysis (TGA) revealed the thermal stability of the nanocomposite while the differential scanning calorimetry (DSC) showed an increasing melting (T(m)) and glass transition (T(g)) temperatures as the fraction of the MWNTs in the nanocomposite was increased. Cyclic voltammetry (CV) allowed the electrodeposition of the nanocomposite film on indium tin oxide (ITO) substrates and subsequent cross-linking of the carbazole pendant group of the PVK to form CPN films. Ultraviolet-visible (UV-vis), fluorescence, and Fourier transform infrared (FTIR) confirmed film composition while atomic force microscopy (AFM) revealed its surface morphology. Four-point probe measurements revealed an increase in the electrical conductivity of the CPN nanocomposite film as the composition of the MWNTs was increased: 5.53 × 10(-4) (3% MWNTs), 0.53 (5%), and 1.79 S cm(-1) (7%). Finally, the interfacial charge transfer resistance and ion transport on the CPN nanocomposite film was analyzed by electrochemical impedance spectroscopy (EIS) with a measured real impedance value of ∼48.10 Ω for the 97% PVK and 3% MWNT ratio of the CPN nanocomposite film.
    ACS Applied Materials & Interfaces 06/2011; 3(7):2300-8. · 5.01 Impact Factor
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    ABSTRACT: We report on the interesting interfacial behavior of oligoethylene glycol or OEGylated linear dendron monolayers at the air-water interface as a function of (a) carbazole dendron generation, (b) the length of the OEG units, and (c) the surface pressure applied upon compression. Surface pressure-area isotherms, hysteresis studies, and isobaric creep measurement revealed a structure-property relationship consistent with the hydrophilic-lipophilic balance of a linear dendron with the OEG group serving as the surface anchor to the water subphase. AFM studies revealed that all the OEGylated carbazole dendrons self-assemble into spherical morphology at low surface pressures but form ribbonlike structures as the surface pressure is increased. This nanostructuring is primarily imparted by the increase in van der Waals forces with increasing amount of carbazole units per dendron generation on a hydrophilic mica surface. Further, electrochemical cross-linking of the carbazole molecules by cyclic voltammetery (CV) on doped Si wafer has enabled the formation of an LB film monolayer with a secondary level of organization in the monolayer imparted by the inter- and intramolecular cross-linking among the carbazole units. This study should provide a basis for monolayer film materials based on combining the LB technique and electrochemical cross-linking for nanostructuring superstructures at the air-water interface.
    Langmuir 06/2011; 27(15):9327-36. · 4.38 Impact Factor
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    ABSTRACT: We describe the capsulation of colloidally templated polythiophene (P3-TAA) arrays with multi-walled carbon nanotubes (MWNTs) after colloidal template electropolymerization. The dissolution of the polystyrene (PS) particle templates, which were assembled via the Langmuir-Blodgett (LB)-like technique, allowed the formation of hollow-shell Janus type arrays.
    Chemical Communications 06/2011; 47(31):8871-3. · 6.38 Impact Factor
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    ABSTRACT: A 2-D molecularly imprinted monolayer (2-D MIM) approach was used to prepare a simple and robust sensor for nitroaromatic compounds with 2,4-dinitrotoluene (DNT) as the model compound, which is a precursor and analog for explosive 2,4,6-trinitrotoluene (TNT). In contrast to studies utilizing long-chain hexadecylmercaptan self-assembled monolayers (SAM)s for sensing, a shorter-chain alkylthiol (i.e., butanethiol SAM) was utilized for DNT detection. The role of the chain length of the coadsorbed alkylthiol was emphasized with a matched template during solution adsorption. Semiempirical PM3 quantum calculations were used to determine the molecular conformation and complexation of the adsorbates. A switching mechanism was invoked on the basis of the ability of the template analyte to alter the packing arrangement of the alkylthiol SAMs near defect sites as influenced by the DNT-ethanol solvent complex. A 2-D MIM was formed on the Au surface electrode of a quartz crystal microbalance (QCM), which was then used to sense various concentrations of the analyte. Interestingly, the 2-D MIM QCM also enabled the selective detection of DNT even in a mixed solution of competing molecules, demonstrating the selectivity figure of merit. Likewise, electrochemical impedance spectroscopy (EIS) data at different concentrations of DNT confirmed the 2-D MIM effectiveness for sensing based on the interfacial conformation and electron-transport properties of the imprinted butanethiol SAM.
    Langmuir 06/2011; 27(11):6768-79. · 4.38 Impact Factor
  • Advanced Materials 06/2011; 23(28):3207-13. · 14.83 Impact Factor
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    ABSTRACT: A facile approach for enabling or inhibiting the adsorption of protein and adhesion of bacterial cells on a potential-induced reversibly wettable polythiophene film is described. The superhydrophobic polymeric surface was first prepared by a two-step process that combines the layering of polystyrene (PS) latex particles via a Langmuir–Blodgett (LB)-like technique followed by cyclic voltammetric (CV)–electrodeposition of polythiophene from a terthiophene ester monomer. The polythiophene conducting polymer coating enabled control of the wettability of the surface by simply changing its redox property via potential switching. The influence of morphology on this switching behavior is also described. The wettability in return controls the adsorption of protein and adhesion of bacterial cells. For instance, the undoped polythiophene film, which is superhydrophobic, inhibits the adhesion of fibrinogen proteins and Escherichia coli (E. coli) cells. On the other hand, the doped film, which is hydrophilic, leads to increased attachment of both protein and bacteria. Unlike most synthetic antiwetting surfaces, the as-prepared superhydrophobic coating is nonfluorinated. It maintains its superhydrophobic property at a wide range of pH (pH 1–13) and temperature (below −10 °C and between 4 and 80 °C). Moreover, the surface demonstrated self-cleaning properties at a sliding angle as low as 3° ± 1. The proposed methodology and material should find application in the preparation of smart or tunable biomaterial surfaces that can be either resistant or susceptible to proteins and bacterial cell adhesion by a simple potential switching.Keywords: superhydrophobic; polythiophene; polystyrene particles; electropolymerization
    Chemistry of Materials. 05/2011; 24(5).
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    Advanced Materials 03/2011; 23(10):1287-92. · 14.83 Impact Factor
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    ABSTRACT: A facile approach and strategy toward binary-composition, two-dimensional (2D) patterned surfaces of conducting polymer periodic arrays, together with thiol self-assembled monolayers (SAMs) is described. The method involved a Langmuir-Blodgett (LB)-like deposition of latex microsphere particles, electropolymerization via cyclic voltammetric (CV) techniques, and self-assembly of an amphiphile. The LB-like technique enabled the monolayer deposition of different sizes of polystyrene (PS) particles in hexagonal packing arrangement on planar substrates. Combining the LB-like method with CV electropolymerization is advantageous because it provides deposition control of a polymer interconnected network, controlled composition ratio of polymer and SAMs, and control of 2D size and spacing of the spherical void pattern. Electrochemical-quartz crystal microbalance (EC-QCM) in situ monitoring of the film deposition quantified a constant and linear growth rate, with varying viscoelastic behavior of the conducting polymer adsorption on planar and PS-templated substrates. The dual-patterned surface provided a good imaging contrast as observed by atomic force microscopy (AFM). Complementary analyses such as X-ray photoelectron spectroscopy (XPS), attenuated total internal reflection infrared (ATR IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy, and static contact angle measurements were used to characterize the formation of the patterned surface. The versatility of the method enables the potential for making various types of quantitative binary compositions and patterned surfaces using different combinations of conducting polymer or functional SAMs, which can be extended in the future to polymer brushes and layer-by-layer assembly of various materials.
    ACS Applied Materials & Interfaces 02/2011; 3(3):817-27. · 5.01 Impact Factor
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    ABSTRACT: We report on the synthesis and electrodeposition of peripheral olefin dendrons with electropolymerizable focal point terthiophene units. These films were utilized for surface initiated ring-opening metathesis polymerization (SI-ROMP) of norbornene to form grafted polynorbornene brushes. The dendrons were first electrodeposited on an electrode surface, forming a highly dense and uniform polythiophene-type film, and their electrochemical behavior was investigated. Subsequently, after activation with a transition metal metathesis catalyst, polynorbornene brushes were grown from the electrodeposited films which were found to be highly dependent on the density of exposed olefin functional groups and dendron generation. The change in film morphology was examined by atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) was used to prove polynorbornene brush film growth and composition on top of the electropolymerized layer. Brush growth kinetics experiments were also carried out to understand the correlation between the structure of the dendrons and polynorbornene brush growth mechanism. The method presented in this paper provides a facile route to prepare robust, uniform, and controllable polymer brushes grafted from an underlying π-conjugated polymer layer.
    Macromolecules. 11/2010;

Publication Stats

60 Citations
114.59 Total Impact Points

Institutions

  • 2012
    • Rice University
      • Department of Chemical and Biomolecular Engineering
      Houston, TX, United States
  • 2010–2012
    • University of Houston
      • • Department of Chemical & Biomolecular Engineering
      • • Department of Chemistry
      Houston, TX, United States