Ethylene Oxide-propylene Oxide Random Copolymer Research Articles

Electrochemical behavior of through-hole electrodeposition inhibitor EO-PO under periodic pulse reverse

Uniform electrodeposition of through-hole (TH) with a high aspect ratio is the key to the reliability of printed circuit board (PCB) interconnection. Inhibitors produce stronger inhibition at high potentials during TH electrodeposition and thus reduce the difference in electrodeposition rates between inside and outside the TH. In this paper, the electrochemical behavior of an ethylene oxide propylene oxide random copolymer (EO-PO) as an inhibitor on the cathode during periodic pulse reverse (PPR) electrodeposition was systematically studied. The results show that EO-PO will rotate under the effect of reverse pulse, and adsorb more strongly on the cathode surface, which inhibits the "cathode stripping" process of the reverse pulse. Through the electrodeposition experiments, compared with direct current (DC) electrodeposition, the PPR method effectively eliminates the copper nodule and improves the concentration window of EO-PO. The results pave the way for regulating and controlling TH electrodeposition with other additives.

Research the Equilibrium Distribution of Puerarin in Aqueous Two-Phase Combine with Temperature-Induced Phase Separation EOPO/ K<sub>2</sub>HPO<sub>4</sub> /Water Systems

The partition behavior of Puerarin in ethylene oxide-propylene oxide random copolymer (EOPO)/ K2HPO4/water systems was investigated .The optimum conditions were EOPO （SDP30） 28%, K2HPO424%, temperature-induced condition was 70°C and 30min. yield of Puerarin could reach 42.26%. Based on the modified model lnK/R2=A*+b*(w”-w’)+c*(w”-w’)2, partition coefficients of Puerarin in EOPO/K2HPO4aqueous two-phase systems were correlated. It was found that the correlation of the experimental data was quite satisfactory.

Measurement of water activities and prediction of liquid–liquid equilibria for water+ethylene oxide-propylene oxide random copolymer+ammonium sulfate systems

The water activities in aqueous mixtures containing ethylene oxide-propylene oxide random copolymer (EOPO) with different molecular weights, both binary and ternary systems, were measured using the improved isopiestic method. The modified NRTL model was extended to predict the phase behavior in polymer+salt aqueous two-phase systems at 298.15 K. The model parameters were evaluated directly from the experimental water activities. The phase diagrams of LLE of EOPO+(NH 4) 2SO 4 aqueous two-phase systems with different molecular weights were successfully predicted using only one group of model parameters. Good agreement with experimental data is obtained, with most of average absolute deviations being less than 2.2 w/w %.

Measurement of phase diagrams for new aqueous two-phase systems and prediction by a generalized multicomponent osmotic virial equation

The liquid–liquid equilibria for ethylene oxide–propylene oxide random copolymer (EOPO)–hydroxypropyl starch (HPS)–water aqueous two-phase systems with various polymer molecular weights were measured at 298.15 K. A generalized multicomponent osmotic virial equation was proposed to predict the phase behavior of new aqueous two-phase systems. By using the vapor–liquid equilibrium (VLE) and/or part of liquid–liquid equilibria (LLE) data (as few as possible), the LLE data of polyethylene glycol (PEG)–HPS, EOPO–HPS and EOPO–salt aqueous two-phase systems were successfully predicted. The results show that the model can give good representation of the phase diagrams.

Utilization of temperature-induced phase separation for the purification of ecdysone and 20-hydroxyecdysone from spinach

An aqueous solution of the ethylene oxide-propylene oxide random copolymer UCON 50-HB-5100 was successfully used to extract ecdysone and 20-hydroxyecdysone from the common spinach plant, Spinacia oleracea. The UCON spinach extract was mixed with a hydroxypropyl starch Reppal PES 200 solution and allowed to form an aqueous two-phase system. After the polymers separated cell debris, proteins and other comtaminants partitioned to the lower Reppal phase and ecdysone and 20-hydroxyecdysone partitioned to the upper UCON phase. The UCON phase was isolated and subjected to a temperature increase to 56°C which induced phase separation between UCON and water. Ecdysone and 20-hydroxyecdysone partitioned between the UCON phase and the water phase at concentrations determined by their degree of hydrophobicity. The less hydrophobic 20-hydroxyecdysone had a greater affinity for the water-rich phase than did ecdysone. Due to the larger volume of the water phase both ecdysteroids were obtained in this phase at 56°C with yields higher than 80%. With 20% ethanol in the primary system recovery was 88.7% for ecdysone and 91.2% for 20-hydroxyecdysone. Results indicate that aqueous two-phase partitioning coupled with temperature-induced phase separation is a quick, easy and inexpensive bench-top technique for extracting and purifying ecdysteroids from raw material. This technique can also be readily up-scaled for commercial use.

Partitioning of ecdysteroids using temperature-induced phase separation

The partitioning behaviour of ecdysone and 20-hydroxyecdysone in aqueous two-phase systems was characterized. Primary systems were composed of an ethylene oxide-propylene oxide random copolymer, UCON 50-HB-5100, and dextran T500. The ecdysteroids were first partitioned in a two-phase system with a UCON-rich upper phase and a dextran-rich lower phase. After the phases had separated, the upper phase was removed and isolated in a separate container. This UCON solution was placed in a water bath and the temperature increased above the cloud point of the polymer. This resulted in the formation of a new two-phase system with an upper water-buffer phase and a lower UCON phase. Ecdysteroids partitioned mainly to the final upper water phase in this new two-phase system. Therefore, temperature-induced phase separation could be utilized to recover UCON polymer and obtain ecdysteroids in a water-buffer solution. The partitioning behaviour was manipulated by adding ethanol, sodium chloride or sodium sulphate to the primary two-phase systems. The recovery of ecdysteroids increased when ethanol was added to the system. In a two-phase systems with an ethanol concentration of 20%, recovery was 73.6% for ecdysone and 85.6% for 20-hydroxyecdysone.