Relaxation phenomena of stereoregular poly(methyl methacrylate) monolayers at the air/water interface

Abstract

Relaxation behaviors of isotactic, atactic, and syndiotactic poly(methyl methacrylate) (PMMA) monolayers at the air/water interface were investigated at three different temperatures. The monolayer characteristics of the three stereoisomers were studied in terms of surface pressurearea per molecule (p-A) isotherm, area relaxation, and pressure relaxation. The results show that pressures at inflection points of p-A isotherms of PMMA decrease with an increase in temperature. The collapse pressure also decreases as the temperature is elevated. It was shown likely for the first time that the relaxation process of PMMA stereoisomers could be described by a model considering the nucleation and growth mechanisms. The simulation parameters of area relaxation of the three stereoisomers at 30 mN/m are very similar, indicating similar mechanisms.

Characteristics and iso‐baric relaxation phenomenon of pmma monolayers with different molecular weights at different temperatures

“…Two inflection points were observed in all the PMMAs with the first transition at 10.9–15.1 mN/m and the second transition at 17.4–20.8 mN/m. The first transition is likely because of isotactic presence in PMMA 10. The second transition suggests a process of phase transition to be a bi‐layer, α‐helix, or β sheet structure 13.…”

“…One transition of inflection point was observed in the range of 18.4–21.4 mN/m. The results of previous investigation10 of atactic PMMA (aPMMA) with M w of 100,000 g/mol at the same temperature are also included in Table I for reference. The limiting area of aPMMA is similar to this study.…”

“…In a previous study of our report,10 relaxation behaviors of isotactic, atactic, and syndiotactic poly(methyl methacrylate) (PMMA) monolayers at the air/water interface were investigated at three different temperatures. The monolayer characteristics of the three stereoisomers were studied in terms of surface pressure‐area per molecule (π‐A) isotherm, area relaxation and pressure relaxation.…”

Miscibility of mixed stereoregular PMMA/PVCN monolayers at the air/water interface

“…The π– A isotherms of monolayers for the three PMMA stereoisomers and PVCN at 25°C are shown, respectively, in Figure 1(a–c). The discussion for the three stereoisomers at three temperatures was reported previously23 and therefore omitted here. The results are consistent with those reported by Beredjick 24…”

Correlation of Relaxation Modeling Parameters of the Studied Polymer Blends at the Air/Water Interface

“…In addition to the relaxation of stereoregualr and different molecular weight PMMA [11][12] monolayers, the Vollhardt model was utilized successfully in a study [13] of relaxation processes of dipalmitoyl phosphatidylcholine monolayers. The bi-exponential decay equation was used in mixed monolayers of alkylated azacrown ethers and palmitic acid [14].…”