New Sulfonated Polystyrene and Styrene–Ethylene/Butylene–Styrene Block Copolymers for Applications in Electrodialysis

In this study we prepared blends of polystyrene (PS) and high-impact polystyrene (HIPS) with poly­(styrene–ethylene–butylene) (SEBS) triblock copolymer. After sulfonation, blends were used to fabricate ion-exchange membranes by solvent-casting and subsequent thermal treatment to obtain homogeneous packing densities. The morphology and structure of the blends were investigated by scanning electron microscopy, atomic force microscopy, and FTIR spectroscopy. Furthermore, the thermal transitions and stability of all the blends were characterized using calorimetric techniques and compared with those of the individual polymers. Analyses of the physical properties (i.e., ionic conductivity, ion-exchange capacity, water uptake, dimensional stability, mechanical properties, etc.) showed that the performance of the PS-containing membranes is, in general, higher than that of the HIPS containing one. Furthermore, the highest sulfonation degree was also found for the PS/SEBS membranes. The capabilities of the membranes were tested by investigating the extraction of Na⁺ by electrodyalisis. Comparison of the percentage of extracted ions indicates that the incorporation of SEBS results in a significant improvement with respect to membranes made of individual polymers

Characteristics (X ± SE) of the study sample, (n = 17).

<p>Characteristics (X ± SE) of the study sample, (n = 17).</p

Sleep latency (minutes taken to fall asleep) during the night-time period of each of the weeks, recorded for 17 work-stressed nurses (X ± S.E.).

<p>(*) p<0.05 with respect to the values obtained in the Control Week.</p

Minutes of real sleep during the night-time period of each of the weeks, recorded for 17 work-stressed nurses (X ± S.E.).

<p>Minutes of real sleep during the night-time period of each of the weeks, recorded for 17 work-stressed nurses (X ± S.E.).</p

Measures of work stress as assessed using the “Effort Reward Imbalance” (ERI) model.

<p>Self Evaluation Questionnaire (Macias et al. 2003).</p><p>(X ± SE) for the study population (n = 17). Stress (E/R)>0.7; high level of stress (E/R) >1.</p

Anxiety measures using the “State-Trait Anxiety Inventory” (STAI).

<p>Self Evaluation Questionnaire (Spielberger et al. 2008).</p><p>(X ± SE) for the study population (n = 17). The 50th percentile for state anxiety: 21. The 50th percentile for trait anxiety: 21.</p

Non-parametric chronobiological parameter; interday stability, intraday variability, and relative amplitude of each of the weeks recorded for 17 work-stressed nurses (X ± S.E.).

<p>Non-parametric chronobiological parameter; interday stability, intraday variability, and relative amplitude of each of the weeks recorded for 17 work-stressed nurses (X ± S.E.).</p

Nocturnal sleep efficiency of each of the weeks, recorded for 17 work-stressed nurses (X ± S.E.).

<p>Nocturnal sleep efficiency of each of the weeks, recorded for 17 work-stressed nurses (X ± S.E.).</p

Total activity during the night-time period of each of the weeks, recorded for 17 work-stressed nurses (X ± S.E.).

<p>(*) p<0.05 with respect to the values obtained in the Control Week.</p

Time in bed during the night-time period of each of the weeks, recorded for 17 work-stressed nurses (X ± S.E.).

<p>Time in bed during the night-time period of each of the weeks, recorded for 17 work-stressed nurses (X ± S.E.).</p