Energy Transfer Study of the Interface Thickness in Symmetrical Isoprene−Methyl Methacrylate Diblock Copolymers

Abstract

We describe direct nonradiative energy transfer (DET) experiments on mixtures of two symmetrical poly(isoprene-b-methyl methacrylate) block copolymers of similar molar mass and composition, bearing different dyes at the junction. One polymer has a donor dye (9-phenanthrene) at the junction, and the other has an acceptor dye (2-anthracene). Small-angle X-ray scattering experiments show that films of the mixed diblock copolymers have a lamellar morphology with a spacing that varies with composition from 24 to 26 nm. Fluorescence decay profiles from these films were analyzed in terms of an energy transfer model that takes account of the distribution of junctions across the interface. On the basis of the value R 0 ) 2.3 nm for the characteristic ET distance and an assumed value of 〈κ 2 〉 ) 0.476 for the preaveraged orientation parameter for randomly oriented immobile dipoles, we calculate an interface thickness of 1.6 ( 0.1 nm. This value is independent of the acceptor/donor ratio (i.e., the acceptor concentration) in the films.

Interface Orientation and Chain Conformation in Simulated Symmetric Diblock Copolymer Lamellar Systems

“…This investigation is performed in relation to ongoing experimental studies of block copolymer interfaces by the direct nonradiative energy transfer (DET) technique. [12,13] Proper interpretation of these experimental data depends on knowledge about the orientation of copolymer chains at the interface and the distribution of junction points between the blocks within the interface. The simulation method used here is the cooperative motion algorithm (CMA), [6,7] which has already been successfully applied for simulation of diblock copolymer melts under various conditions ranging between the homogeneous and the strong segregation limits.…”

Synthesis of polyisoprene–poly(methyl methacrylate) block copolymers via a two‐electron‐transfer mechanism

“…Isoprene copolymers were previously obtained with anionic,4–13 cationic,14, 15 coordination,16, 17 and radical polymerization3, 4, 18, 19 techniques. Such copolymers are interesting because they can be used for rubber production, as effective compatibilizers for natural rubber/acrylic polymer blends,3, 19 and as potential materials for medical applications 20, 21…”

Photochemical and Photophysical Studies of and in Bulk Polymers

“…For a random distribution of donors and acceptors, the donor fl uorescence intensity decay I D ( t ) can be described by a modifi ed F ö rster equation (Eq. 11.14 ) 99 :…”

“…99 The polymers were labeled at the block junctions as shown in Chart 11.6 . Films were prepared by mixing individual polymers in a solvent and casting the solution.…”