Micro-Brownian Motion of Polymer Segments in a Monolayer at the Air−Water Interface:  A Time-Resolved Study of Intralayer Energy Transfer

Abstract

This work is concerned with micro-Brownian motion of polymer segments on a water surface, which is observed as the lateral diffusion of fluorescence probes attached to the polymer chains. Poly(vinyl octanal acetal)s labeled with phenanthrene (P: energy donor) and anthracene (A: energy acceptor) are spread on water, yielding a stable monolayer in which the probes are able to take statistically random distributions in the two-dimensional plane. The time-resolved fluorescence analysis of the energy transfer between the P and A probes allows us to evaluate the acceptor densities and lateral diffusion coefficients of polymer segments on the water surface. The result is obtained by fitting the fluorescence decay data with the theoretical prediction by the Monte Carlo simulation. It is found that this polymer forms a viscous monolayer, in which the lateral diffusion of polymer segments takes place with a diffusion coefficient of ca. 8 × 10-8 cm2 s-1.

Polymerization of Substituted Acetylenes Carrying Non-Polar and Polar Groups with Transition Metal Acetylide Catalysts

“…[1,2] The copolymerization of substituted acetylenes carrying non-polar and polar groups is very attractive because the copolymers can be endowed with unique physical properties, such as amphiphilicity. [3] Catalysts for the copolymerization of substituted acetylenes bearing nonpolar and polar groups must be capable of polymerizing both kinds of substituted acetylenic monomers. Efficient catalysts for the polymerization of both polar and non-polar acetylenic monomers are rare.…”

Photoisomerizable Guanosine Derivative as a Probe for DNA Base-Pairing in Langmuir Monolayers

“…In order for diffusion to be important during the irradiation cycle, the molecules would have to travel far enough so that a change in illumination intensity (described by f ( x , y ) in eq 7) would become significant. By using 10 –7 cm 2 /s as an estimate for the diffusion constant, 57 we obtain the average distance traveled by a molecule to be 0.5 mm. At this distance, the relative change in f ( x , y ) in our irradiation setup can be at most 6%.…”

Temperature-Dependent Shape-Memory Textiles: Physical Principles and Applications

“…For polymers, this contact is also known as the micro-Brownian motion, where an interdiffusion among the molecules occurs. In addition, distinct conformational states can be available as the molecules can be presented in different configurational states for the same energy level [36][37][38]. This "lack" of energy does not occur in shape-memory polymers because their programmable memory allows the chains to return to the original position without any significant "entanglement" effect that dissipates some energy portion.…”