Properties of polystyrene‐poly(methylmethacrylate) random and diblock copolymers in dilute and semidilute solutions

Abstract

Solution properties for random and diblock copolymers of polystyrene (PS) and poly(methyl methacrylate) (PMMA) have been measured by dynamic and total intensity light scattering in solvents of differing quality. The results are compared with the corresponding properties for PS and PMMA homopolymers of similar molecular weight, in order to determine if interactions between unlike monomers are significant. The hydrodynamic radius (Rh) and diffusion second virial coefficient (kd) for the random copolymer are found to be larger than the corresponding values for the homopolymers in a solvent which is near‐theta for the two homopolymers, whereas no such effect is observed for the block copolymer. This suggests that most intrachain interactions occur a relatively short distance along the chain backbone. In a mutual good solvent Rh and kd of the random copolymer are comparable to the average of the values for the homopolymers, indicating that in a good solvent monomer/solvent interactions dominate over monomer/monomer interactions. For an isolated diblock copolymer in a mutual good solvent, there is no evidence that interactions between unlike monomers lead to additional expansion of the entire molecule, as measured by Rh, nor expansion of the individual blocks as probed by light scattering with one block optically masked. However, at low but finite concentration there is evidence (the coefficients of the binary interaction terms in the viscosity and the mutual diffusion coefficient, and the second and third virial coefficients) that a weak ordering effect may exist in block copolymer solutions, far from the conditions where microphase separation occurs. Finally, measurements of ternary polymer‐polymer‐solvent solutions show no dependence on monomer composition or monomer distribution for the tracer diffusion of probe PS‐PMMA copolymers in a PMMA/toluene matrix. This indicate that the frictional interaction is largely unaffected by interactions between unlike monomers. However, there is evidence that the thermodynamic interaction is more unfavorable between a random copolymer and the homopolymer matrix than between a diblock and the matrix. © 1994 John Wiley & Sons, Inc.

Coil‐Globule Collapse in Flexible Macromolecules

“…Some experimental studies have been reported on dilute, semi-dilute, and concentrated solutions of random and block copolymers. [107,108] …”

Reverse-phase high performance liquid chromatography (RP-HPLC) as a powerful tool to characterise complex water-soluble copolymer architectures

“…[6][7][8][9] To a similar degree as molecular weight and chemical composition, the segmentation of copolymers was shown to have a major impact on the physical properties of the resulting materials, including their stability, solvation or self-assembly behaviour. [10][11][12][13] For example, polymer sequence was demonstrated to affect the glass transition temperature of copolymers of ethylene glycol methyl ether acrylate (EGMEA) and tert-butyl acrylate (tBA). 14 In other example, segmentation was also shown to have a dramatic influence on the interaction of copolymers with lipid membranes.…”

Dynamic Light Scattering from Multicomponent Polymer Solutions

“…Correlation functions were obtained on either of two instruments, as previously described [9,10]; each employs an Ar+ laser operating at 488 nm. Scattering angles ranged from 30 to 135 degrees.…”