Hydroxypropylcellulose solutions

At concentrations c c+, the concentration dependence of t] follows equally accurately a power law 

Here a is a scaling prefactor, v and x are scaling exponents, and ryo and rj are dimensional prefactors. 

To avoid model-dependent phrasings, Phillies and Quinlan termed the c c+ and c c+ domains the solutionlike and meltlike regimes. At the transition, T] is continuous. Furthermore, the transition is analytic not only the functions but also their hrst derivatives are continuous. There is no crossover regime one form or the other describes t] c) at every concentration. Systematic reviews of the literature showed that such transitions happen in some, but definitely not all, other polymer solutions(54,55). In natural units the transition concentration c+[r/] for different systems has a wide range of different values. HPC water is distinguished by the very low polymer concentration at which the transition occurs, namely c+[r/] 4. 

The nonuniversality of the transition concentration, the lack of a matching transition in (c), indeed, the complete lack of such a transition in many polymer systems, all 

For clarity, the remaining literature in this section is discussed in chronological order. Work by Phillies and Quinlan had been preceded by extensive optical probe diffusion studies of HPC water solutions Brown and Rymden used QELSS to examine 72 nm radius PSL spheres diffusing in solutions of hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), carboxymethylcellulose (CMC), and polyacrylic acid(PAA)(56). The focus was polymer-induced cluster formation, indicated by the substantial decreases in Dp and increases in the second spectral cumulant as seen at very low (0.001 g/g) concentrations of HEC and HPC. These changes were substantially reversed by the addition of 0.15% Triton X-100. The Dp of spheres was reduced by the addition of small amounts of fully-charged pH 9 CMC, but addition of TX-lOO had no effect in CMC solutions. Brown and Rymden also examined sphere diffusion in nondilute polymer solutions. Relatively complex dependences of Dp on concentration were suppressed by the addition of TX-IOO. In the presence of TX-lOO, simple stretched-exponential concentration dependences were observed, but the second spectral cumulant still increased with increasing polymer concentration. 

---

Grizzuti, N. Cavella, S. Cicarelli, P. Transient and steady-state rheology of liquid crystalline hydroxypropylcellulose solution. J. Rheol. 1990,... 

Back, S.G. Magda, J.J. Cementwala, S. Normal stress difference in liquid-crystalline hydroxypropylcellulose solutions. J. Rheol. 1993, 37 (5), 935-945. 

Godinho, M.H. van der Klink, J.J. Martins, A.F. 90. Shear-history dependent equilibrium states of liquid-crystalline hydroxypropylcellulose solutions... 

FUJ Fujii, S., Sasaki, N., and Nakata, M., Rheological studies on the phase separation of hydroxypropylcellulose solution systems, J. Polym. Sci. Part B Polym. Phys., 39, 1976, 2001. 

The effect of field strength E on electrophoretic mobility was studied by Mitnik, et al. (26) and by Heller(27). Mitnik, et al. examined dsDNA fragments of size 72-23 000 bp passing through 1 MDa hydroxypropylcellulose solutions. For each probe, at lower fields p, is nearly independent of E. At larger fields, p, E for X (0.2,0.4) X increases as c is increased. At each matrix concentration, for each... 

Figure 5.7 Concentration dependence of Ds/Dgo of fluorescein in aqueous hydroxypropylcellulose solutions against HPC concentration, based on measurements of Mustafa, et al. 32). The solid line is a simple exponential. Note the lack of change of slope at the lyotropic phase transition near w hpc 0.4. Measurements were made with polymers having Mw of 60, 300, and 1000 kDa, Ds(c) of the solvent being independent of A u.

Bu and Russo used FRAP to measure the diffusion of fluorescein and nine larger probes through hydroxypropylcellulose solutions(22). Nominal matrix molecular weights were 60,300, and 1000 kDa. Detailed results were presented for the 300 kDa matrix polymer, as seen in Figure 9.13. Fluorescein diffusion was nearly unimpeded by the matrix polymer. Probe particles diffuse more rapidly than expected from the macroscopic solution viscosity. Note that increased toward rj with increasing R, and Dp(c) for each probe fits well to a simple exponential, except perhaps for the largest probe. Comparison was made by Bu and Russo with the Langevin-Rondelez equation, which describes these data well(23). 

O Connell, et al. moved from studying probes in hydroxypropylcellulose solutions to studying S(q,t) of the polymer itself(70). They used QELSS to examine the mode structure of probe-free aqueous 1 MDa HPC solutions. The S q,t) of nondilute polymer solutions is primarily treated in Chapter 11 however, O Connell, et al. s work is so tightly integrated with probe diffusion studies that it appears here. 

As part of a study of probe diffusion, Yang and Jamieson report the shear viscosity T] (Figure 12.6c) of hydroxypropylcellulose solutions(29). The z-average molecular weights were 110,140,450, and 850 kDa solution viscosities r]/rjQ were as large as 45. The 7 (c) for each molecular weight is described well by a stretched exponential. 

Extended analysis of all spectral parameters for hydroxypropylcellulose solutions, in particular the relative behavior of smaller and larger probe particles, impUes that these solutions are characterized by a single, concentration-independent, length scale that is approximately the size of a polymer coil. This scale is significantly... 

Werbowyj, R.S. and Gray, D. G., 1981, Ordered phase formation in concentrated hydroxypropylcellulose solutions, Macromol., 13 69. 

---