Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Filters applied. Clear all
. 2018 May 21;11(5):850.
doi: 10.3390/ma11050850.

Polysulfobetaines in Aqueous Solution and in Thin Film Geometry

Affiliations
Free PMC article

Polysulfobetaines in Aqueous Solution and in Thin Film Geometry

Bart-Jan Niebuur et al. Materials (Basel). .
Free PMC article

Abstract

Polysulfobetaines in aqueous solution show upper critical solution temperature (UCST) behavior. We investigate here the representative of this class of materials, poly (N,N-dimethyl-N-(3-methacrylamidopropyl) ammonio propane sulfonate) (PSPP), with respect to: (i) the dynamics in aqueous solution above the cloud point as function of NaBr concentration; and (ii) the swelling behavior of thin films in water vapor as function of the initial film thickness. For PSPP solutions with a concentration of 5 wt.%, the temperature dependence of the intensity autocorrelation functions is measured with dynamic light scattering as function of molar mass and NaBr concentration (0⁻8 mM). We found a scaling of behavior for the scattered intensity and dynamic correlation length. The resulting spinodal temperatures showed a maximum at a certain (small) NaBr concentration, which is similar to the behavior of the cloud points measured previously by turbidimetry. The critical exponent of susceptibility depends on NaBr concentration, with a minimum value where the spinodal temperature is maximum and a trend towards the mean-field value of unity with increasing NaBr concentration. In contrast, the critical exponent of the correlation length does not depend on NaBr concentration and is lower than the value of 0.5 predicted by mean-field theory. For PSPP thin films, the swelling behavior was found to depend on film thickness. A film thickness of about 100 nm turns out to be the optimum thickness needed to obtain fast hydration with H₂O.

Keywords: dynamic light scattering; phase behavior; polysulfobetaines; polyzwitterions.

Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Chemical structure of the polyzwitterions under investigation, PSPPn [18]. R2 serves as label for future UV-Vis spectroscopy. For R1, the degree of polymerization is n = 80, while for R2, n = 85 and 280.
Figure 2
Figure 2
Representative results from DLS on a 5 wt.% solution of PSPP280 in H2O. (a) Left axis: Intensity autocorrelation functions at θ = 90° and 30 °C in relation to NaBr concentration, as indicated in the graph. The time ranges of the curves differ because they were measured on two different instruments, see the Materials and Methods Section. Right axis: Corresponding distribution functions of relaxation times in equal area representation, τA(τ) vs. log(τ); (b) Relaxation rate, Γ, of PSPP280 in 1.4 mM NaBr in H2O at 25.3 °C vs. q2. Symbols: measured data, line: linear fit through the origin.
Figure 3
Figure 3
(a,b) Scattered intensities in relation to temperature; (c,d) Same intensity data in relation to reduced temperature, τ, in log-log representation. Symbols: experimental data as detailed in the legend of (a), lines: fits. (a,c) PSPP85, (b,d) PSPP280 at 5 wt.% in H2O and at the NaBr concentrations indicated. The intensities are normalized to the incoming flux. The temperature range of the lines corresponds to the data points used for the fits. In (c,d), only points from the one-phase state are plotted, i.e., at temperatures on the higher side of the intensity maximum.
Figure 4
Figure 4
Cloud points measured by turbidimetry (black closed circles, [32]) and spinodal temperatures from fits of Equation (1) to the scattered intensity, Ts,I (blue open up triangles), and of Equation (2) to the dynamic correlation lengths, Ts,ξ (red open down triangles). (a) PSPP85 and (b) PSPP280, both at 5 wt.% in H2O. The lines guide the eye. (c,d) Exponents γ from Equation (1) (c) and ν from Equation (2) (d). Black squares: PSPP85, blue circles: PSPP280.
Figure 5
Figure 5
(a,b) Dynamic correlation lengths, ξD, as function of temperature. The T-range of the lines corresponds to the data points used for the fits. (c,d) Same intensity data in dependence on reduced temperature, τ, in log-log representation. Symbols: experimental data as in Figure 3, lines: fits of Equation (2) (a,c) PSPP85, (b,d) PSPP280.
Figure 6
Figure 6
(a) Evolution of the relative humidity inside the vapor chamber. The curve is fitted with an exponential function; (b) Swelling ratio of the PSPP80 film upon increasing relative humidity at 12 °C measured in-situ with SR. The data are fitted by a theoretical model, see text.

Similar articles

See all similar articles

References

    1. Hoffman A.S. Applications of thermally reversible polymers and hydrogels in therapeutics and diagnostics. J. Controlled Release. 1987;6:297–305. doi: 10.1016/0168-3659(87)90083-6. - DOI - PubMed
    1. Gil E.S., Hudson S. Stimuli-responsive polymers and their bioconjugates. Prog. Polym. Sci. 2004;29:1173–1222. doi: 10.1016/j.progpolymsci.2004.08.003. - DOI
    1. Roy D., Brooks W.L.A., Sumerlin B.S. New directions in thermoresponsive polymers. Chem. Soc. Rev. 2013;47:7214–7243. doi: 10.1039/c3cs35499g. - DOI - PubMed
    1. Hocine S., Li M.H. Thermoresponsive self-assembled polymer colloids in water. Soft Matter. 2013;9:5839–5861. doi: 10.1039/c3sm50428j. - DOI
    1. Aseyev V., Tenhu H., Winnik F.M. Non-ionic thermoresponsive polymers in water. Adv. Polym. Sci. 2011;242:29–89. doi: 10.1007/12_2010_57. - DOI
Feedback