AFM OBSERVATION OF SINGLE-CHAIN PMMA PARTICLES

Atomic force microscopy (AFM) has been applied to observe single-chain polymethylmethacrylate (PMMA) particles that were stored for six mont hs at room temperature after being sprayed from very dilute solutions in good solvents, good/poor mixed solvents, and a theta solvent. Nearl y monodisperse PMMA standards of molecular weights ranging from 7.90 x 10(4) to 1.3 x 10(6) were used to investigate the effect of molecular weight (MW) on the size of the single-chain PMMA particles. These sin gle-chain particles showed close to spherical shapes. The morphology o f single-chain PMMA particles of a given molecular weight has found to be identical in spite of different solvents used for solution sprayin g. Molecular weight dependence of the particle dimension was also foun d. The diameters of single-chain PMMA particles after correction of ti p-geometry effect were compared with the values estimated from molecul ar weight and density.