The rates of chain aggregation of poly(methyl methacrylate) (PMMA) in acetonitrile (AcN) and in the mixed solvent of AcN+water (10 vol %) were determined by static light scattering and compared with the rates of chain collapse. Dilute solutions of PMMA with the molecular weight mw =6.4× 106 and in the concentration range of (0.8-5) × 10-4 0.3em g/cm3 were quenched below the cloud point, and the weight-average molecular weight Mw and z -average square radius of gyration S2 z for clusters of PMMA chains were measured as a function of the time t after the quench and the concentration c. The measurement of chain aggregation was carried out up to the cluster size of Mw mw ∼30, which required time periods of hours to several days depending on the concentration and solvent. The chain aggregation in AcN+water occurred much faster than that in AcN. The growth of clusters in both the solvents was represented by the exponential function as Mw ∼ egct and S2 z ∼ ehct, where g and h represent the intrinsic rate of chain aggregation. The ratio σ of the intrinsic rate in AcN+water to that in AcN was estimated to be 9 by taking a rough average of the ratios 9.4 obtained from g and 8.8 from h. This value is comparable to the ratio 11 of the rate of chain collapse of PMMA in AcN+water (10 vol %) to that in AcN. This close value of the ratios indicates that the nature of solvent would affect the rates of chain collapse and chain aggregation through a similar mechanism.
|Journal||Physical Review E - Statistical, Nonlinear, and Soft Matter Physics|
|Publication status||Published - Oct 27 2008|
All Science Journal Classification (ASJC) codes
- Statistical and Nonlinear Physics
- Statistics and Probability
- Condensed Matter Physics