Microphase-separated diblock copolymer

As a final example of catalytic hydrogenation activity with polymer-stabilized colloids, the studies of Cohen et al. should be mentioned [53]. Palladium nanoclusters were synthesized within microphase-separated diblock copolymer films. The organometallic repeat-units contained in the polymer were reduced by exposing the films to hydrogen at 100 °C, leading to the formation of nearly monodisperse Pd nanoclusters that were active in the gas phase hydrogenation of butadiene. 

Zehner RW, Sita LR. Electroless deposition of nanoscale copper patterns via microphase-separated diblock copolymer templated self-assembly. Langmuir 1999 15 6139-6141. 

The l(Mig period of the regularly packed microdomains, as illustrated in Fig. 9.12, can be determined by the small-angle X-ray scattering. One may make a scaling analysis on the equilibrium domain sizes from the calculation of free energy changes as follows. In comparison to the macrophase-separated polymer blends, the microphase-separated diblock copolymer system contains mainly two... 

Yamada, K., Nonomura, M., and Ohta, T. (2004) Kinetics of morphological transitions in microphase-separated diblock copolymers. Macromolecuks. 

Riess [60] gave a first description of the phase behavior of linear ternary triblocks. While in microphase separated diblock copolymers only one structural feature ean exist like lamella, cylinder, or sphere, ternary block copolymers can simultaneously exhibit different features in the microphase separated state (e.g., spheres within a cylinder or lamella, etc.). 

In section III we discussed the diffusion of a homopolymer chain comprised of N monomer segments into a highly entangled melt where it was shown that its tracer diffusion coefficient, D, varied as and that the temperature dependence of D /T was virtually the same as that of the inverse of the zero shear-rate viscosity of the homopolymer. Here we discuss the diffusion of homopolymers into microphase-separated diblock copolymer structures. 

The bulk properties of microphase-separated diblock copolymers are well understood. Studies show that the relative volume fraction of each component of a microphase separated copolymer essentially determines the structure that it exhibits,If the average volume fraction of one of the blocks of the copolymer chain is between 0.4 and 0.6 then the equilibrium structure is comprised of alternating lamellae of each component. When the volume fraction of the minor component is less than 0.2 it forms spherical microdomains, exhibiting a body-centered cubic structure, in a matrix of the major component. The minor component forms cylindrical microdomains which exhibit a hexagonal close-packed (hep) structure in the major component of its volume fraction is between 0.2 and 0.4. It has recently been shown that these cylindrically shaped microdomains form a structure which exhibits a double diamond-like symmetry when the volume fraction of the minor component lies in the narrow regime between those which predict the formation of the lamellar and the cylindrical microdomains arranged in a hep structure.The size of the microphase separated domains is determined by the total length of the copolymer chain. 

Nojima S., Nakano H., and Ashida T. (1993) Crystallization behaviour of a microphase-separated diblock copolymer. Polymer 34 4168-4170. 

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