Dual-functional ROMP-based betaines: effect of hydrophilicity and backbone structure on nonfouling properties

Foundational materials for nonfouling coatings were designed and synthesized from a series of novel dual-functional zwitterionic polymers, Poly[NRZI], which were easily obtained via ring-opening metathesis polymerization (ROMP) followed by a single step transformation of the cationic precursor, Poly[NR(+)], to the zwitterion, Poly[NRZI]. The resulting unique dual-functional structure contained the anion and the cation within the same repeat unit but on separate side chains, enabling the hydrophilicity of the system to be tuned at the repeat unit level. These dual-functional zwitterionic polymers were specifically designed to investigate the impact of structural changes, including the backbone, hydrophilicity, and charge, on the overall nonfouling properties. To evaluate the importance of backbone structure, and as a direct comparison to previously studied methacrylate-based betaines, norbornene-based carbo- and sulfobetaines (Poly[NCarboZI] and Poly[NSulfoZI]) as well as a methacrylate-based sulfobetaine (Poly[MASulfoZI]) were synthesized. These structures contain the anion-cation pairs on the same side chain. Nonfouling coatings were prepared from copolymers, composed of the zwitterionic/cationic precursor monomer and an ethoxysilane-containing monomer. The coatings were evaluated by using protein adsorption studies, which clearly indicated that the overall hydrophilicity has a major influence on the nonfouling character of the materials. The most hydrophilic coating, from the oligoethylene glycol (OEG)-containing dual-functional betaine, Poly[NOEGZI-co-NSi], showed the best resistance to nonspecific protein adsorption (Γ(FIB) = 0.039 ng/mm(2)). Both norbornene-based polymers systems, Poly[NSulfoZI] and Poly[NCarboZI], were more hydrophilic and thus more resistant to protein adsorption than the methacrylate-based Poly[MASulfoZI]. Comparing the protein resistance of the dual-functional zwitterionic coatings, Poly[NRZI-co-NSi], to that of their cationic counterparts, Poly[NR(+)-co-NSi], revealed the importance of screening electrostatic interactions. The adsorption of negatively charged proteins on zwitterionic coatings was significantly less, despite the fact that both coatings had similar wetting properties. These results demonstrate that the unique, tunable dual-functional zwitterionic polymers reported here can be used to make coatings that are highly efficient at resisting protein adsorption.     

Photophysical properties of PPP and PPV derivatives bearing polystyrene or polycaprolactone as side groups

This contribution reports on detailed photophysical investigations of poly(p-phenylene) PPP and poly(p-phenylene-vinylene) (PPV) derivatives laterally decorated with polystyrene (PPV-PSt) or poly(ε-caprolactone) (PPP-PCL, PPP-altPCL, PPV-PCL and PPV-PCL-Br). The polymers emit blue and exhibit very high relative and absolute photoluminescence quantum yield, Φ_f, in dilute solution, thin film (spin-coated and inkjet-printed) and bulk state. This is ascribed to the presence of the lateral macromolecules, which suppress the strong π-π interactions and consequently excimers formation. Lower Φ_f value was obtained for the bromine containing polymer and its corresponding model compound dibromodistyrylbenzene Br₂-DSB, which was ascribed to heavy atom effect enabling intersystem crossing from S₁ to T₁. However, studies at 77 K did not reveal phosphorescence, in contrast an enhancement of the fluorescence intensity with respect to room temperature measurement was observed.     

Primitivity of finitely presented monomial algebras

We study prime monomial algebras. Our main result is that a prime finitely presented monomial algebra is either primitive or it has GK dimension one and satisfies a polynomial identity. More generally, we show that this result holds for the class of automaton algebras; that is, monomial algebras that have a basis consisting of the set of words recognized by some finite state automaton. This proves a special case of a conjecture of the first author and Agata Smoktunowicz.     

Discovery of Novel Sulfonamide‐Based 5‐Arylidenerhodanines as Effective Carbonic Anhydrase (II) Inhibitors: Microwave‐Assisted and Ultrasound‐Assisted One‐Pot Four‐Component Synthesis,Molecular Docking,and Anti‐CA II Screening Studies

The synthesis of N‐substituted‐5‐arylidenerhodanines was carried out by the optimized one‐pot sequential four‐component procedure with the condensation between 4‐aminobenzenesulfonamide, suitable aldehyde, ethyl bromoacetate, and carbon disulfide. In addition to traditional method, microwave‐irradiated and ultrasound‐irradiated techniques were implemented in water at ambitious conditions, and the target compounds were obtained in high yields and purity without purification methods. The enzyme inhibition activity of newly synthesized compounds on carbonic anhydrase (II) was also evaluated. The reference inhibitor molecule was sulfanilamide, the IC₅₀ value of which was 3.5 μM. It was also found that the IC₅₀ values of all examined molecules were in nanomolar level and much smaller than those of sulfanilamide. The inhibition between 93.5 and 99.6% was observed in the presence of new compounds synthesized in the present study at the accessible maximum concentration in the reaction mixtures. 5j , among the tested compounds possessing the lowest IC₅₀ value, was found to be the most potent carbonic anhydrase (II) inhibitor.     

Modelling effects of degree of crystallinity on mechanical behavior of semicrystalline polymers

Viscoplasticity theory based on overstress (VBO) which is one of the unified state variable theories is extended to account for crystallinity ratio () on mechanical behavior of semicrystalline polymers. The modifications on VBO are done considering the semicrystalline polymeric materials somewhat as a composite material since it consists of amorphous and crystalline phases. Amorphous and crystalline phase resistances are arranged in two different analog models: amorphous stiffness and flow are in parallel and series with crystalline phase. Apart from many existing work in the literature, not only uniaxial loading are modeled but also creep and relaxation behaviors are simulated for a hypothetical material. It is shown that when amorphous and crystalline phase resistances acting in parallel are considered in the model, creep, relaxation and uniaxial loading and unloading behaviors can be simulated well using the modified VBO. In addition, uniaxial compression loading and unloading behavior of highly crosslinked ultra-high molecular weight polyethylene (UHMWPE) and creep behavior of polytetrafluoroethylene (PTFE) with different crystallinity ratios are simulated using the proposed VBO model where amorphous and crystalline phases are parallel. Simulation results are compared to the experimental data by Kurtz et al. (2002) and Sun et al. (2005) [Kurtz, S.M., Villarragaa, M.L., Herra, M.P., Bergström, J.S., Rimnacc, C.M., Edidin, A.A., 2002. Thermomechanical behavior of virgin and highly crosslinked ultra-high molecular weight polyethylene used in total joint replacements. Biomaterials 23, 3681–3697; Sun, H., Cooke, R. S., Bates, W. D., Wynne, K.J., 2005. Supercritical CO₂ processing and annealing of polytetrafluoroethylene (PTFE) and modified PTFE for enhancement of crystallinity and creep resistance. Polymer 46, 8872–8882] respectively and good match with experimental data is obtained.     

Effects of band mixing on the radiative properties of a quantum well

The effect of band mixing and non-parabolicity on quantum well gain and spontaneous emission is studied using k.p theory. Spectra of gain and spontaneous emission are strongly modified but the relation of maximum gain versus nominal current density is not strongly affected.     

Characterization of Iron Sulfide Species in Model Solutions by Cyclic Voltammetry. Revisiting an Old Problem

A long‐standing problem associated with voltammetric determination of iron and sulfide in reduced natural waters has been the nature of the presumed analyte responsible for a reduction peak at ?1.1 V vs. Ag/AgCl. Cyclic voltammetry at the Hg electrode is used here to study solutions with different Fe(II) to sulfide ratios in chloride and acetate electrolytes (pH 6–7). The results indicate that the ?1.1 V peak can be assigned to reduction of Fe²⁺ or its labile complexes on FeS layers that partially cover the Hg electrode. Hg electrodes covered with FeS act like FeS solid electrodes over a very wide potential range (?0.35 to ?1.9 V). Two mechanisms for forming FeS layers on Hg are described. Over the broadest deposition potential range, the dominant mechanism involves attachment at the Hg surface of FeS nanoparticles, which are generated quickly in initially supersaturated mixtures of Fe(II) and S(–II). In a narrow deposition potential range, roughly ?0.56 to ?0.70, FeS layers are produced additionally by replacement of preformed HgS. Because Fe²⁺ is reduced at ?1.1 V on FeS layers and at ?1.4 V on bare Hg, it may be underdetermined when only the ?1.4 V peak is measured.     

Local analytic first integrals of planar analytic differential systems

We study the existence of local analytic first integrals of a class of analytic differential systems in the plane, obtained from the Chua?s system studied in L.O. Chua (1992, 1995), N.V. Kuznetsov et al. (2011), G.A. Leonov et al. (2012) , ,  and . The method used can be applied to other analytic differential systems.     

High temperature pyrolysis of poly(phenylene vinylene)s with poly(ε-caprolactone) or polystyrene side chains

Journal of Thermal Analysis and Calorimetry - High temperature pyrolysis studies of poly(phenylene vinylene)s PPVs with lateral substituents poly(ε-caprolactone) (PPV–PCL) or...     

Effects of electrospinning process parameters on nanofibers obtained from Nylon 6 and poly (ethylene-n-butyl acrylate-maleic anhydride) elastomer blends using Johnson SB statistical distribution function

The impact strength of Nylon 6 can be further improved by blending it with ethylene-butyl acrylate-maleic anhydride elastomer. The blending is achieved in solution phase. Due to incompatibility of Nylon 6 and the elastomer, a special mixture of solvents is used to dissolve both components. The solution is electrospun, and the effects of the process parameters on the expected radii of nanofibers are investigated. The effects of process parameters such as polymer concentration in solution, electrical field, diameter of the syringe needle, feed rate, and collector geometry on nanofibers were investigated. Statistical analysis is carried out using the Johnson S_B distribution. A relation is proposed to relate the effect of the process parameters feed rate, electrical voltage, and tip to collector distance on the expected diameter of fibers. It is found that concentration and electrical field have a profound effect on the diameter of fibers compared to those of the syringe diameter and feed rate.