Narrow Results

In capillary polymer electrophoresis, the property of polymer sieving matrix dominates the migration behavior of DNA/RNA. We investigated the capillary electrophoresis of RNA ranging from 100 nt to 10,000 nt in polyacrylamide (PA) solutions with different molecular weights (Mw) and different concentrations. We observed that the resolution length (RSL) of RNA fragments was improved and the migration time was prolonged, when polymer concentration was increased. The resolution for small RNA fragments ($<$1000 nt) was improved with the increase of polymer concentration, whereas the large ones ($>$3000 nt) became inseparable. In addition, we estimated the smallest resolvable nucleotide length (Ls) by the plot of RSL against RNA size.

The corrosion inhibition of mild steel in 1 M H₂SO₄ in the presence of polyvinylpyrollidone (PVP) and polyacrylamide (PA) as inhibitors at 30–60°C was studied using gravimetric and gasometric techniques. The inhibition efficiency (1%) increased with increase in concentration of the inhibitors. Increase in temperature increased the corrosion rate in the absence and presence of inhibitors but decreased the inhibition efficiency. Both PVP and PA were found to obey Temkin adsorption isotherm and Kinetic-Thermodynamic Model of El-Awady at all the concentrations and temperatures studied. Phenomenon of physical adsorption is proposed from the activation parameters obtained. Thermodynamic parameters reveal that the adsorption process is spontaneous. PVP was found to be a better inhibitor than PA.

The inhibitive performance of two water soluble polymers–polyacrylamide (PA) and polyvinylpyrrolidone (PVP) on the corrosion behavior of aluminum alloy 3SR in HCl solution was investigated using weight loss, hydrogen evolution, and thermometric methods at 30–60°C. Results obtained indicate that both polymers inhibited acid-induced corrosion of aluminum at the temperatures studied. PVP was found to be a better corrosion inhibitor than PA. All measurements from the three techniques show that inhibition efficiencies increase with increase in inhibitor concentration and decrease with increase in temperature. This indicates that the inhibitive actions of the polymers were mainly due to adsorption. Adsorption of these inhibitors follows Temkin and El-Awady adsorption isotherm models. Kinetic/thermodynamic parameters (E_a, K_ads, ) of adsorption of the studied inhibitors reveal that the adsorption was physical in nature and spontaneous. Differences in inhibition efficiency of the two polymers could be linked to their differences in molecular structure.

Monodisperse micron-sized polyacrylamide (PAM) particles with a regular shape have been successfully prepared through dispersion polymerization of the monomer using a rotary reactor. FTIR and NMR spectroscopic results demonstrated the formation of PAM. POM and TEM observations revealed that PAM particles had a regular shape and good dispersity. A thick layer of surfactant (PVP) still existed on PAM particles after multiple centrifugation and ultrasonic re-dispersion in ethanol, which indicates a strong interaction between PVP and PAM. The effects of various polymerization factors on the average size of PAM particles have also been studied.

Controlled polymerization of N-n-propylacrylamide was achieved by atom transfer radical polymerization (ATRP) in a N,N-dimethylformamide-water mixture (50 vol%) at room temperature with methyl 2-chloropropinonate as initiator and CuCl/tris(2-dimethylaminoethyl)amine as the catalytic system in a ratio of 1:1:1. High molecular weight homopolymers (up to 3.7 × 10⁴) with narrow molecular weight distribution (less than 1.2) were obtained. The living character of the polymerization was further demonstrated by self-blocking experiment. An inverse molecular weight dependence of the cloud point of narrow-dispersed poly(N-n-propylacrylamide) aqueous solution was determined by turbidimetry and differential scanning calorimetry, especially for the low molecular weight samples.

Potassium iron hexacyanoferrate/polyacrylamide nanohybrid hydrogel (PB/PAM-gel) was successfully synthesized via a convenient one-pot gamma radiation route. The as-prepared PB/PAM-gel has compact internal three-dimensional porous structures with well-dispersed PB nanowires, which exhibit good elasticity and excellent swelling performance. The adsorption experiments reveal that the PB/PAM-gel can rapidly and selectively adsorb Cs${}^{+}$ from the solution in a wide range of pH. The maximum adsorption capacity reaches 131mgg${}^{-1}$. This nanohybrid hydrogel is very stable and can be easily separated from the solution after adsorption. It can be applied as a potential adsorbent for Cs${}^{+}$ removal from radioactive wastewater.

In this paper, a new method is developed to fabricate underwater superoleophobic films using a cross-linked cationic and ionic polyacrylamide followed by a simple template-free soaking process. The surface properties of these films are characterized through atomic force microscopy (AFC) and contact angle measurements. The results demonstrated that the immersion time had a significant impact on the morphology and wettability of the films. After 0.5∼2 hours of immersion in NaCl (0.2 mol/L) solution, the formations of numerous micro- and nano-structures can be observed on the film surface; resulting in an enhanced water/oil contact angle, achieving the desired superoleophobic range. The smallest sliding angle was obtained as 0.5° under the optimal immersion time of 1 hour.