Rigoberto C. Advincula

Electropolymerization molecularly imprinted polymer (E-MIP) SPR sensing of drug molecules: pre-polymerization complexed terthiophene and carbazole electroactive monomers.

A novel chemosensitive ultrathin film with high selectivity was developed for the detection of naproxen, paracetamol, and theophylline using non-covalent electropolymerized molecular imprinted polymers (E-MIP). A series of monofunctional and bifunctional H-bonding terthiophene and carbazole monomers were compared for imprinting these drugs without the use of a separate cross-linker. A key step is the fast and efficient potentiostatic method of washing the template, which facilitated enhanced real-time sensing by surface plasmon resonance (SPR) spectroscopy. Various surface characterizations (contact angle, ellipsometry, XPS, AFM) of the E-MIP film verified the templating and release of the drug from the cross-linked conducting polymer film.

Antimicrobial graphene polymer (PVK-GO) nanocomposite films

The first report on the fabrication and application of a nanocomposite containing poly-N-vinyl carbazole (PVK) polymer and graphene oxide (GO) as an antimicrobial film was demonstrated. The antimicrobial film was 90% more effective in preventing bacterial colonization relative to the unmodified surface. More importantly, the nanocomposite thin film showed higher bacterial toxicity than pure GO-modified surface.

Superhydrophobic Colloidally Textured Polythiophene Film as Superior Anticorrosion Coating

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.

Surface initiated polymerization from nanoparticle surfaces

Abstract The synthesis, characterization, and development of new nanoparticle materials have both scientific and technological significance. Surface initiated polymerization (SIP) from nanoparticle surfaces involves the growth of end‐tethered polymer brushes where the length or thickness can be more than twice the radius of gyration (Rg) compared to a free polymer in solution. Different mechanisms are possible on a variety of initiators, reaction conditions, monomers, and nanoparticles. Important differences to solution and bulk polymerization can be observed where the nanoparticles with grafted initiators behave as macroinitiators. In turn, the development of these materials will allow the preparation of thermodynamically and kinetically stable nanocomposites and colloids. Through the careful use of surface sensitive spectroscopic and microscopic techniques, much has been gained from the direct and in‐situ analysis of grafted polymers on the nanoparticles with regards to the kinetics and mechanism of the polymerization process. Parallels can be drawn to SIP on flat surfaces where surface sensitive spectroscopic and microscopic measurements are complementary to analysis methods for colloidal particles. Thus, this review surveys the different polymerization mechanisms and procedures towards forming core‐shell types of hybrid inorganic–organic polymer nanoscale materials.

Superhydrophobic–Superoleophilic Polythiophene Films with Tunable Wetting and Electrochromism

IO N There is much interest in superhydrophobic surfaces, as inspired by the non-wetting properties of the lotus leaf. [ 1 ] It can give a water contact angle greater than 150 ° with only 2–3% of the water droplet coming into contact with its surface, which is a common test for designating synthetic superhydrophobic surfaces. [ 1 ] The high water repellency is well worth mimicking because of the myriad industrial and practical applications, namely self-cleaning coatings, antifouling marine coatings, microfl uidics, antibiofouling, and anti-ice adhesion properties. [ 2 ] Here we report a novel and facile preparation of a nonfl uorinated superhydrophobic–superoleophilic polythiophene coating with reversibility to a superhydrophilic-and-oleophobic surface via electrochemical polymerization on a 2D layered colloidal particle template. Interestingly, such fi lms exhibit both simultaneous reversible electrochromic and extreme wettability properties by simply changing the voltage (potential) ex situ. Such a reversible wettability property can result in highly controlled wetting behavior with possible dual applications in self-cleaning coatings, channeling of fl ow properties, controlled membrane separations, and regenerable surfaces together with electro-optical functionality (electrochromic) by a mere switch of the applied potential. Artifi cial superhydrophobic surfaces can be accomplished by developing a dual-scale roughness structure and tuning of surface energy. [ 3 ] Most reports [ 2 , 3 ] have been on synthetic superhydrophobic surfaces fabricated using fl uorinated polymers and small molecule compounds, which are markedly known as low-surface-energy coating materials. [ 4 ] Fluorinated small molecule compounds in particular are more expensive and deemed to have some detrimental effects with bioaccumulation to the environment. [ 5 , 6 ] Therefore, these concerns necessitate the development of nonfl uorinated superhydrophobic coatings with other inherently useful functionality or properties. [ 7 , 8 ]

Electrochemical Surface Plasmon Resonance and Waveguide-Enhanced Glucose Biosensing with N-Alkylaminated Polypyrrole/Glucose Oxidase Multilayers

In this work, we report an electrochemical surface plasmon resonance/waveguide (EC-SPR/waveguide) glucose biosensor that could detect enzymatic reactions in a conducting polymer/glucose oxidase (GO(x)) multilayer thin film. In order to achieve a controlled enzyme electrode and waveguide mode, GO(x) (negatively charged) was immobilized with a water-soluble, conducting N-alkylaminated polypyrrole (positively charged) using the layer-by-layer (LbL) electrostatic self-assembly technique. The electrochemical and optical signals were simultaneously obtained from the composite LbL enzyme electrode upon the addition of glucose as mediated by the electroactivity and electrochromic property of the polypyrrole layers. Signal enhancement in EC-SPR detection is obtained by monitoring the doping-dedoping events on the polypyrrole. The real-time optical signal could be distinguished between the change in the dielectric constant of the enzyme layer and other nonenzymatic reaction events such as adsorption of glucose and the change of the refractive index of the solution. This was possible by correlation of both the SPR mode and the m = 0 and 1 modes of the waveguide in an SPR/waveguide spectroscopy experiment.

Polyelectrolyte adsorption processes characterized in situ using the quartz crystal microbalance technique: alternate adsorption properties in ultrathin polymer films

Abstract The alternate adsorption processes of polyelectrolytes from solution have been investigated in situ using a functionalized (gold electrode) quartz substrate via the quartz crystal microbalance (QCM) technique. The deposition process involved the alternate layer by layer electrostatic (Coulombic) interaction between oppositely charged adsorbing polyelectrolytes resulting in ultrathin multilayer films. Three kinds of polyelectrolyte combinations were used: poly(diallyldimethylammonium chloride) (PDADMAC), poly(ethylenimine) (PEI) and poly(allylamine hydrochloride) (PAH) as the cationic polymers and poly(sodium-4-styrensulfonate) (PSS) as the anionic polymer for polycation/polyanion combinations. The electrical behavior of the piezoelectric ‘quartz crystal’ was sensitive to the adsorption properties of the polyelectrolytes, thus allowing close observation of the time-dependent adsorption processes. The adsorption relationship was explored for different polyelectrolyte pair-combinations, alternate solution concentration and the presence of rinsing and drying steps. The results showed that the amount of frequency change is mostly dependent on the immediate subphase environment of the crystal surface, i.e. aqueous environment versus air in relation to the classic Sauerbrey equation.

Antimicrobial applications of electroactive PVK-SWNT nanocomposites.

The antibacterial properties of a nanocomposite containing an electroactive polymer, polyvinyl-N-carbazole (PVK) (97 wt %), and single-walled carbon nanotubes (SWNT) (3 wt %) was investigated as suspensions in water and as thin film coatings. The toxic effects of four different PVK-SWNT (97:3 wt %) nanocomposite concentrations (1, 0.5, 0.05, and 0.01 mg/mL) containing 0.03, 0.015, 0.0015, and 0.0003 mg/mL of SWNT, respectively, were determined for planktonic cells and biofilms of Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis). The results showed that the nanocomposite PVK-SWNT had antibacterial activity on planktonic cells and biofilms at all concentration levels. Higher bacterial inactivation (94% for E. coli and 90% for B. subtilis) were achieved in planktonic cells at a PVK-SWNT concentration of 1 mg/mL. Atomic force microscopy (AFM) imaging showed significant reduction of biofilm growth on PVK-SWNT coated surfaces. This study established for the first time that the improved dispersion of SWNTs in aqueous solutions in the presence of PVK enhances the antimicrobial effects of SWNTs at very low concentrations. Furthermore, PVK-SWNT can be used as an effective thin film coating material to resist biofilm formation.

Surface-initiated polymerization

1 D.E. Bergbreiter, A.M. Kippenberger: Hyperbranched Surface Graft Polymerizations.- 2 R.R. Bhat, M.R. Tomlinson, T. Wu, J. Genzer: Surface-Grafted Polymer Gradients: Formation, Characterization and Applications.- 3 W.J. Brittain, S.G. Boyes, A.M. Granville, M. Baum, B.K. Mirous, B. Akgun, B. Zhao, C. Blickle, M.D. Foster: Surface Rearrangement of Diblock Copolymer Brushes - Stimuli Responsive Films.- 4 A. Naji, C. Seidel, R.R. Netz: Theoretical Approaches to Neutral and Charged Polymer Brushes.-

Electrochemical Deposition and Surface-Initiated RAFT Polymerization: Protein and Cell-Resistant PPEGMEMA Polymer Brushes

This paper introduces a novel and versatile method of grafting protein and cell-resistant poly(poly ethylene glycol methyl ether methacrylate) (PPEGMEMA) brushes on conducting Au surface. The process started with the electrochemical deposition and full characterization of an electro-active chain transfer agent (CTA) on the Au surface. The electrochemical behavior of the CTA was investigated by cyclic voltammetry (CV) while the deposition and stability of the CTA on the surface were confirmed by ellipsometry, contact angle, and X-ray photoelectron spectroscopy (XPS). The capability of the electrodeposited CTA to mediate surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization on both the polymethyl methacrylate (PMMA; model polymer) and PPEGMEMA brushes was demonstrated by the increase in thicknesses of the films after polymerization. Contact angles also decreased with the incorporation of the more hydrophilic brushes. Significant changes in the morphologies of the films before and after polymerization were also observed with atomic force microscopy (AFM) analyses. Furthermore, XPS results showed an increase in the O 1s peak intensity relative to C 1s after polymerizations, which confirmed the grafting of polyethyleneglycol (PEG) bearing brushes. The ability of the PPEGMEMA-modified Au surface to resist nonspecific adhesion of proteins and cells was monitored and confirmed by XPS, ellipsometry, contact angle, AFM, and fluorescence imaging. The new method presented has potential application as robust protein and cell-resistant coatings for electrically conducting electrodes and biomedical devices.