Temperature-sensitive surfaces were prepared by grafting poly(N-isopropylacrylamide) (PNIPAAm) hydrogel on the surface of silicone wafers. The silicone wafer substrates were modified by organosilane (vinyltriethoxylsilane). They were further reacted with N-isopropylacrylamide (NIPAAm), using N,N′methylenebisacrylamide as the cross-linking agent, to generate the cross-linked PNIPAAm layer on the surface of the substrate. The surfaces modified by the cross-linked PNIPAAm layer were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and attenuated total reflectance-Fourier transform infrared (FTIR) spectroscopy. The reversible hydrophilic/hydrophobic properties of the surface were evaluated by the dynamic contact angle. The morphology of the surface modified by a crosslinked PNIPAAm layer can be turned from "sea island" to "mountain valley" by changing the molar ratio of NIPAAm to BisAAm and by varying the polymerization time. A completely hydrophilic surface (advancing contact angle ) 0°) was observed below 25 °C, and the surface became extremely hydrophobic (advancing contact angle ) 92°) above 40 °C. The sensitivity of the surfaces to temperature change can be improved by increasing the cross-linking density of the polymer layer and varying the polymerization time. The water meniscus height in a capillary tube, whose wall was coated by a cross-linked PNIPAAm layer, went up or down as the temperature changed to below or above the lower critical solution temperature of PNIPAAm. The differences in the water meniscus heights are 10 and 5 mm for a capillary tube with a diameter of 2 and 3 mm, respectively, corresponding to a change in temperature from 23 to 50 °C. The temperature-sensitive characteristics, which produce remarkable and rapid changes of surface properties, make this technology applicable for use as actuators, modulators, sensors, and switches.

To develop an effective transition-metal-ion adsorbent material, functionalization of amine (−NH2) onto fine-grained activated carbon (AC) was performed via the electrophilic aromatic substitution of nitro (−NO2) groups onto the aromatic backbone of the AC, followed by reduction of −NO2 to −NH2. Fourier transform infrared, Brunauer−Emmett−Teller surface area analysis, gravimetric method, and batch metal ion adsorption experiments were performed in parallel on unmodified AC and amine-functionalized AC (NH2-AC). The competitive adsorption of transition-metal ions (Cd2+, Cu2+, Ni2+, and Pb2+) was measured in batch experiments at pH 2.0−5.8. Metal ions favored the NH2-AC over the unmodified AC. Based on the distribution coefficients (K d), the NH2-AC had an affinity for metal ions in decreasing order of Cu2+ ≫ Pb2+ > Ni2+ > Cd2+. On the NH2-AC, the copper adsorption equilibrium was reached within 1 min with a saturation loading capacity of 0.86 mmol of Cu/g, 2.5 times greater than that on the unmodified AC. The Langmuir and Redlich−Peterson isotherm models were used successfully to characterize the Cu2+ adsorption isotherms. Having K d values up to 100 000, the NH2-AC is a useful adsorbent material for removing Cu2+ from aqueous wastes.

A thermal-sensitive surface was prepared on the surface of a silicone wafer (substrate) by an ultraviolet photografting reaction between a photosensitizer, (N,N′-diethylamino)dithiocarbamoylpropyl(trimethoxy)silane, and N-isopropylacrylamide. Ellipsometery measurement revealed a thin grafting layer (∼44 Å) consisting of a single terminal poly(N-isopropylacrylamide) (PNIPAAm) chain on the surface of the silicone wafers. X-ray photoelectron spectroscopy confirmed that the grafting layer was composed of the PNIPAAm structure. The properties of the grafting layer can be adjusted and manipulated by varying the photopolymerization time and the concentration of the monomer. Increasing the photopolymerization time and the concentration of the monomer increases both the thickness of the grafting layer and the wettability of the surface. The characteristics of the temperature-sensitive surface were investigated by dynamic contact angle as a function of temperature. The remarkable change on advancing contact angle can be observed around 32 °C. Compared with the substrate grafted by PNIPAAm gel, the substrate with a signal-terminal PNIPAAm chain exhibited a lower transition temperature and a narrower change range of transition temperature. This can be attributed to the mobile PNIPAAm chain with a single-terminal mode, which increases the characteristics of faster response to the temperature change.

Anatase particles (40-60 nm) were coated with an organosilane monolayer terminated with an ethylenediamine (EDA) ligand. These functionalized nanoparticles (FNPs) were then treated with an aqueous solution of Cu(II) to create a cationic Cu-EDA complex bound to the nanoparticle surface. Cu(II) and EDA ligand incorporation were confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The Cu(EDA)2 FNP was then studied for its binding affinity for pertechnetate anion from a Hanford groundwater matrix. The Cu(EDA)2 FNP was also evaluated for its injectability into a porous medium for possible application as a subsurface semipermeable reactive barrier. Injection was readily accomplished, and resulted in a highly uniform distribution of the FNP sorbent in the test column.

Two new materials for adsorption of metal ions from aqueous media have been developed. The organic functional groups amine ( -NH 2 ) and sulfonate (-SO 3 H) were successfully attached to a commercially available fine-grained activated carbon (AC) via electrophilic aromatic substitutions. The surface properties of the materials were investigated using FTIR spectroscopy, XPS, BET surface area analysis, gravimetric methods, and elemental analysis. The NH 2 -AC and SO 3 H-AC each had a functional group density of 3 mmol/g. Batch metal ion adsorption experiments were conducted to determine metal binding properties of the adsorbent materials. Based on the distribution coefficients (K d ) of metal ions tested, the unmodified AC and sulfonated-AC both had an affinity for metal ions in decreasing order of Nd . Lu % La . Pb . Cu . Ni % Cd . Mn % Ca, while the amine-AC had an affinity for metal ions in the order of Cu ) Nd % Lu % La . Pb . Ni . Cd . Mn % Ca. With maximum K d values of 130,000 for amine-AC and 25,000 for sulfonated-AC, compared to a K d of 2,000 for unmodified AC, the modified activated carbons have a strong potential for use in removing heavy metal ions and lanthanide ions from aqueous wastes.