Density, Refractive Index, pH, and Cloud Point Temperature Measurements and Thermal Expansion Coefficient Calculation for PPG₄₀₀, PE62, L64, L35, PEG₄₀₀, PEG₆₀₀, or PEG₁₀₀₀ + Water Systems

Abstract

Thermophysical properties and phase behavior of seven {polymer (1) + water (2)} systems were determined using PPG 400 , Ultraric PE62, Pluronic L64, Pluronic L35, PEG 400 , PEG 600 , and PEG 1000 . Density (ρ) and refractive index (n) were measured for the whole range of w 1 at T = 293.2 K. Correlation with Redlich−Kister equation and prediction with Lorentz−Lorenz theoretical model were done. pH was measured for different mass fractions at ambient temperature (T ≈ 298.2 K). Cloud point temperature (T cloud ) was measured for different polymer mass fractions (w 1 ) from 0.02 up to 0.30. The thermal expansion coefficient (α T ) was calculated for w 1 = 0.15 and temperature (T) from 278.2 up to 348.2 K. Experiments were conducted at atmospheric pressure (P ≈ 95 kPa). The obtained thermophysical properties indicate that PEGs + water have the highest ρ while PPG 400 + water has the smallest ρ. Also, all ρ vs w 1 curves present a maximum value. n profiles are similar for all systems, showing the same refractive index increment for w 1 below 0.4. Density (Δρ) and refractive index (Δn) deviations are higher for the PPG 400 + water system, mainly due to the highest propylene content and hydrophobic character of PPG units. Moreover, pH varies with polymer mass fraction reaching a minimum value, probably because polymers release H + in solution. Phase transition results indicate that Tcloud and α T present related behaviors, i.e., when solution became turbid, α T shows an abrupt change in slope.

In Situ Dissolution and Swelling of Confined Lamellar Polymer Crystals through Exposure to Humid Air

“…10%. 34 Therefore, we conclude that we may have underestimated the change in the thickness of the swollen PEO layer by 10% at maximum, which is close to the uncertainty of the results derived from optical interference measurements.…”

“…Accordingly, the interference color of the film reflects the optical path, allowing us to deduce the thickness of the polymer film in the range of 10–700 nm. Applying this principle, the color of the imaged PS- b -PEO platelets can be translated into thickness values h pl , , employing the intensities of the red, green, and blue (RGB) channels of the used microscope camera (AXIOCAM ICc 1, Zeiss, Oberkochen, Germany). The high lateral resolution of optical microscopy provided a possibility for precisely detecting variations in thickness h pl ( x , y ) within the ( x , y ) plane of the substrate and across the platelets.…”

Elastomeric Optical Waveguides by Extrusion Printing

“…[ 25 ] While crosslinked networks containing low concentrations (<10 wt.%) of Pluronic‐DA are not completely transparent due to network inhomogeneities, [ 26 ] Pluronic‐DA gels (>20 wt.%) show high transparency that is maintained after photocrosslinking. [ 27 ] Crosslinked Pluronic‐DA exhibits lower RI than PDMS (RI < 1.4 for Pluronic gels at < 50 wt.%) [ 28 ] and elastomeric mechanical properties. [ 26a,29 ] Pluronic‐DA, therefore, appears to be a suitable cladding material in elastomeric PDMS‐based core/cladding waveguides for in vivo applications.…”