Initial swelling behavior

In addition to monomers and the initiator, an inert liquid (diluent) must be added to the monomer phase to influence the pore structure and swelling behavior of the beaded resin. The monomer diluent is usually a hydrophobic liquid such as toluene, heptane, or pentanol. It is noteworthy that the namre and the percentage of the monomer diluent also influence the rate of polymerization. This may be mainly a concentration or precipitation effect, depending on whether the diluent is a solvent or precipitant for the polymer. For example, when the diluent is a good solvent such as toluene to polystyrene, the polymerizations proceed at a correspondingly slow rate, whereas with a nonsolvent such as pentanol to polystyrene the opposite is true. 

Baker, JP Hong, LH Blanch, HW Prausnitz, JM, Effect of Initial Total Monomer Concentration on the Swelling Behavior of Cationic Acrylamide-Based Hydrogels, Macromolecules 27, 1446, 1994. 

Temperature dependent swelling behavior of the poly(AAm-BMA) gel consisting 10% BMA (Initial gel), PAAc gel (secondary gel) and IPNs composed of poly(AAm-co-BMA-10) with PAAc are shown in Fig. 11 and compared with a corresponding random copolymer gel. The IPNs and random gels show... 

Figure 5 shows the swelling behavior of the model acrylic latexes as determined by photon correlation spectroscopy. Changes in particle diameter are shown instead of radius as in Figures 3 and 4. The diameter, d, at each pH was divided by the initial diameter, d0, determined at pH = 5 (unexpanded). In general shape, the curves are similar to those determined by sedimentation and viscometry. The initial points occurred at a higher pH due to the much lower particle concentration. No effort was made to lower the initial pH with acid consequently, the undesirable salt effect was avoided. 

When cells are suddenly suspended in a hypoosmotic medium they initially swell as if they were perfect osmometers, but a few minutes later they down-regu-late their volume, thereby approaching the volume they had at the start. This behavior has been termed regulatory volume decrease (RVD). RVD, however, does not completely return the cell volume to normal (Figure 1). The extent of this remaining volume deviation, which is equivalent to a steady-state change in cell... 

Moreover, such a hnear relationship tends to demonstrate that the actual cross-linking degree of the APCNs is only dependent on the initial molar fraction in PCLDMA crosshnkers introduced in the polymerization medium and therefore attests for the absence of additional (physical) cross-links that could be due to polymer chain entanglements. Therefore and owing to the control over the molecular parameters of the APCNs, a correlation between gel stracture and swelling behavior could be predicted from the Flory-Rehner relationship in the particular case of this study with a constant composition in PCL of about 30%. 

Figure 6 shows the time histories of the vertical and the horizontal stress with the experimental result for the test (d). Simulated vertical stress agrees with the monitored. On the other hand, the horizontal stress was slightly different. One reason is the initial disturbance of the experiment because of the complicatedness of the apparatus. However, the most influential reason is the anisotropy of the swelling pressure. The direction of compaction of the buffer material plays an important role for the swelling behavior. The further study on the anisotropy has to be continued. 

---