2 compressions


2 expansions


material adsorbed at the interface remains constant over time, without irreversible dissolution in

the aqueous subphase (Figure 4-10). As the PCL content is decreased, monolayer stability is

reduced. For Star#2, the compression-expansion cycles start shifting toward smaller mean

molecular areas, and this shift is even more pronounced for Star#1 (Figure 4-11). For these two

samples, the small PCL chains are insufficient to overcome the overall star hydrophilicity arising

from the water-soluble PEO core, and irreversible water dissolution takes place over time.


25


20



 5-



 10


000 10000


'12000


Figure 4-10. Compression-expansion hysteresis plot of Star#6 (target pressure = 9 mN/m).

 25


 20
 h First compression
 15 -I c First expansion
 a Second compression
 *Second expansion







 0 1000 2000 3000 4000
 MMA (AZ)

Figure 4-11. Compression-expansion hysteresis plot of Star#1 (target pressure = 9 mN/m).


0 2000 4000 6000 8(
 MMA (iA2)