Irena Gancarz

Modification of polysulfone membranes 4. Ammonia plasma treatment

Abstract The effect of NH3 and NH3/Ar plasma on ultrafiltration polysulfone membranes have been studied. Results of contact angle, FTIR–ATR and X-ray photoelectron spectroscopy experiments clearly showed that both plasmas introduced hydrophilic, nitrogen- and oxygen-containing moieties on the polymer surface and that NH3/Ar plasma was more efficient. That plasma was also more aggressive––signs of strong etching could be seen on the SEM pictures. Redeposition of etched material seemed to take place inside the pores. On the contrary, ammonia plasma was soft and caused cleaning the surface and pores enlargement. Performance of ammonia plasma modified membranes was greatly improved and independent on solution pH. The last observation proved amphoteric character of the surface. NH3/Ar plasma treatment gave membranes of acidic surface and filtration indices not so good as for ammonia plasma.

Plasma modified polymers as a support for enzyme immobilization II. Amines plasma

Polysulfone films were modified by ammonia, n-butylamine and allylamine remote plasma using various sample-toplasma distances. Contact angle measurements, FTIR-ATR and XPS spectroscopy proved the presence of polar, including amine, groups on the modified surface. Presence of argon in the plasma environment made the plasma more stable and in most cases left the surface more hydrophilic but with a lower amount of nitrogen moieties on it. Glucose isomerase was successfully immobilized on the plasma-treated samples. Its activity correlates well with the concentration of C–N bonds on the surface. The highest enzyme activity was achieved for samples treated with allylamine/Ar plasma close to the plasma edge. � 2003 Elsevier Ltd. All rights reserved.

Plasma modified polymers as a support for enzyme immobilization 1. Allyl alcohol plasma

The paper describes deposition of plasma polymerized allyl alcohol on polysulfone film. It is shown that film surface becomes more hydrophilic after plasma treatment independently on presence of argon in a reaction mixture. The chemistry of the new surface layer was established by FTIR-ATR and ESCA spectroscopy. The substrate placed close to the plasma edge was the most hydrophilic but the amount of hydoxyl groups was not the highest there. Presence of argon stabilized the plasma but the deposited layer contained relatively less oxygen-bearing functionalities. The plasma treated polymer was subjected to xylose isomerase immobilization. For this purpose the divinylsulfone method was adapted. The studies revealed no correlation between the surface hydrophilicity and efficiency of immobilization.

Failure of aminophosphonate synthesis due to facile hydroxyphosphonate - phosphate rearrangement

Abstract In a Kabachnik-Fields synthesis of aminophosphonates amines can catalyse the formation of hydroxyphosphonates, and their further rearrangement to phosp

ON THE REVERSIBILITY OF HYDROXYPHOSPHONATE FORMATION IN THE KABACHNIK-FIELDS REACTION

Abstract The reversibility of hydroxyphosphonate synthesis in the Kabachnik-Fields synthesis was studied. It was found that in all studies cases which included aliphatic and aromatic aldehydes or ketones the hydroxyphosphonates decompose to the starting ketone and dialkyl phosphite in the presence of aliphatic amines as determined by 1H-, 13C-, 31P-NMR.

A PDMS/LTCC bonding technique for microfluidic application

A novel bonding method of glass-covered low-temperature co-fired ceramics (LTCC) to transparent polydimethylsiloxane (PDMS) polymer is reported in this paper. The irreversible bonding between both materials was achieved by exposing their surfaces to an oxygen plasma. The influence of different plasma treatment process parameters (system power, time of surfaces activation) and glass/ceramics firing temperatures (Tmax = 700–875 °C, co-fired, post-fired) on the bonding process was investigated. Scanning electron microscopy (SEM) was used to study the glass surface quality after firing at various temperatures. Contact angle measurements, x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) and atomic force microscopy (AFM) were used to investigate properties of the PDMS and glass-covered LTCC surfaces before and after oxygen plasma treatment.

Plasma nanostructuring of porous polymer membranes.

Several methods for membrane modification have been presented. Chemical modification of a neat polymer followed by membrane formation and modification of just formed membranes have been compared to plasma action. The following plasma modes are discussed in detail: treatment with non-polymerizable gases, treatment with vapors and plasma initiated grafting. Some examples of modified membrane properties are given. Finally, it was concluded that plasma treatment offers the fastest, environment friendly and versatile method that allows tailoring brand new membranes.

N-butylamine plasma modifying ultrafiltration polysulfone membranes

Abstract Some properties of ultrafiltration polysulfone membranes modified with n-BuNH2 and n-BuNH2/Ar plasmas were studied. Contact angle measurements, XPS and SEM were used to characterize the surface changes. Pore size estimation, water transport and filtration parameters helped to describe changes in filtration performance. Presence of argon in plasma environment stabilized plasma but made it more aggressive; pore size increased and surface etching took place. This plasma grafted a smaller number of nitrogen features — most of them in the form of amine. Excellent filtration performance was observed for BuNH2/Ar plasma-modified membranes in an acidic environment.

Argon plasma-assisted PDMS?LTCC bonding technique for microsystem applications

A method for transparent polymer (polydimethylosiloxane, PDMS) to glass-covered low-temperature co-fired ceramics (LTCC) using microwave argon plasma is reported in this paper. Changes in the composition of both materials before and after plasma treatment are investigated with x-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy-attenuated total reflection and contact angle measurements. The results obtained for PDMS and glass-covered LTCC modified with argon plasma are compared with previously reported results received for oxygen plasma. Moreover, a comparison of adhesion between PDMS and glass-covered LTCC bonded together using Ar and O2 plasma is made using a material testing machine.

RETRO ABRAMOV VS. REARRANGEMENT PATH COMPETITION IN HYDROXYPHOSPHONATE DECOMPOSITION

Abstract 1-hydoxyphosphonates in the presence of aliphatic amine undergo two competitive processes: retro Abramov reaction and intramolecular hydroxyphosphonate-phosphate rearrangement. Both reaction rates and their ratio strongly depend on the nature of the substituent on a alpha carbon atom. Kinetic experiments indicate that two reactions proceed via common transition state.