Critical gel concentration

Fig. 3.1 Illustration of the critical micelle concentration (cmc) and critical gel concentration (cgc) in a block copolymer solution.

Abbreviations as Table 3.1 + ege, critical gel concentration. Abbreviations as Table 3.3. 

Fig. 4.18 Critical gel concentration versus l/<5, where <5, is the thermodynamic expansion factor, for PF.O-PBO diblocks (Booth et al. 1997).

Han and Bae have demonstrated that an aqueous solution of a copolymer of 2-5mol% acrylic acid and NIPAAm exhibits reversible gelation without significant hysteresis (8). The critical gel concentration (CGC) in this case was 4% by weight. Gelation, rather than precipitation, was attributed to polymer chain entanglements and to the weak physical association of polymer precipitates while hydration was maintained by an ionized segment of AAc (7,8). 

Fig. 97. Critical gel concentration of solutions in DMF of various PAN samples, differing in molecular weight, plotted vs reciprocal temperature. in kg/mok (O) 192, (O) 286, (A) 36(k ( ) 462. Reproduced from Colloid Polym Sci [Ref. 309] by the courtesy of the auAors and of Steinkopff Verlag Darmstadt, FRG...

Ross-Murphy has criticised the model on a number of grounds [498,499] and most particularly on a) the assumption of high order kinetics with n 2 (n = 4.5 for iota carrageenan and 12.5 for kappa carrageenan) and b) the absence of a critical gel concentration c . He derived an alternative equation... 

Figure 7. Dependence of the critical gel concentration (Cgep upon the prepolymer molecular weight in a,to -Mg dicarboxylato polymers (toluene, 25 0 ( ) PMS, ( ) PTBS, (x) PBD, (A)PIP and ( ) PS.

Microfibrous self-aggregation of porphyrins substituted by didodecyl L-glutamic acid 8 was investigated by Sagawa and Ihara s group (Fig. 3). The aggregation occurred even at a low concentration below the critical gel concentration. hi the mixed system with the corresponding pyrene derivative... 

Figure 7 illustrates the viscoelastic behavior near the critical gel concentration of gellan whose crosslink points are thought to form by... 

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