ABSTRACT
FIG. 19 Relationship between number of alkyl chains and surface tension (y erne) of the telomers with Pn 10-11. pH 2, 25°C. e: xR12-2VPQ with Pn II, 0 : xR12-4VPQ with Pn 10. (From Ref. 52 with permission of Japan Oil Chemists' Society.)
Pn 10. The surface tensions attain 33-35 mN m-1 for xR12-2VPQ with x = 3.2-9.5 and 37mNm-1 for xR12-4VPQ with x = 3.2. However, upon increasing the dodecyl chains, lowering the surface tension of xR12-4VPQ is less effective than that of xR12-2VPQ. It is clear that xR12-2VPQ orients densely at the air-water interface and shows great surface activities, because the chains of xR12-2VPQ orient in the nearly same direction to the skeletal hydrocarbon chains and the orientations are effective, while those in xR124VPQ orient reversely. The surface tensions are influenced by the polymerization degree of the telomers. The Ycmcs of 1.9-4.5R1r2VPQ with Pn 20 and 2.9-13.7R12-4VPQ with Pn 19 are 44-48 and 54--59mNm-1, respectively. xR12-2VPQ with Pn 20 shows higher efficiencies in lowering the surface tension than xR1r4VPQ Pn 19, while these telomers with Pn 19-20 are less effective than those with Pn 10-ll. The surface tensions of polysoaps of the quaternized 2-vinylpyridine with Pn 560 are 57 mN m-1 at a concentration of0.5% and 52mNm-1 at a concentration of 1% [55,56]. The telomers with Pn about 20 show less effective surface activities due to the bending of the skeletal hydrocarbon chains, like polysoaps. On the other hand, the telomers with Pn about 5 show excellent surface activities. They are also influenced by the alkyl chain length of the telomers. Table 2 shows the values of the CMC and the Ycmc of xR12-2VPQ with Pn 4--6 in aqueous solutions at pH 2. In the case of an alkyl chain length of 12, upon increasing the dodecyl chains, the telomers reduce the surface tension and the CMCs shift to lower
concentration. In particular, the CMC of 3.4R12-2VPQ is 1/760th of that of N-dodecylpyridinium [42], a conventional cationic surfactant. The telomers having 2-3 octyl or dodecyl chains orient by both one terminal alkyl chain and introduced alkyl chains, giving large occupied areas, and those having 34 octyl or dodecyl chains orient densely by the introduced alkyl chains due to the interactions between their chains, giving small ones.
