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We have published extensively on a lattice dendrimer model whose properties were simulated by a Monte Carlo technique. However, it has recently been pointed out that the simulation technique violated detailed balance and that the ensuing errors, at least for dendrimers without excluded volume, were relatively large. In this contribution we show how the technique can be efficiently modified to satisfy detailed balance, and we report results on dendrimers as high as G = 11. When applied to dendrimers with excluded volume, we find that the older technique generates only relatively small errors, and we are therefore confident that our previous results are qualitatively valid. We also discuss our model in light of recent neutron scattering studies concerned with the distribution of end groups.

Hybrid copolymers with dendritic−linear blocks are shown to exhibit many of the classic microphase-separated structures of linear−linear block copolymers. Transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS), and small-angle neutron scattering (SANS) were used to evaluate the morphology of a sixth generation (G6) poly(benzyl ether) dendron covalently bonded to linear polystyrene (PS) at the dendron focal point. Increasing the fraction of the linear block, φPS, through an increase in the molecular weight of the PS block revealed morphologies evolving from disordered to ordered lamellar to hexagonally close-packed dendron cylinders. Significantly, the observed morphologies are distinct from those expected for analogous linear−linear blocks at equivalent volume fraction, although the direction of progression follows expectation. Quantitative analysis suggests substantial molecular deformation or shape change in the dendritic phase. The possible role of conformational entropy in determi...

A small mass concentration of poly(benzyl ether) dendrimer added to a low molecular mass polystyrene is found to inhibit the dewetting of a thin (≈50 nm) polystyrene film from an acid-etched silicon substrate. The inhibition effect is found to depend on generation number where the lowest generation (G = 3) tested was the most effective. Our findings are qualitatively similar to previous observations by Barnes et al. [Macromolecules 2000, 33, 4177−4185.] where the addition of fullerenes (“buckyballs”, C60) similarly inhibited the dewetting of thin polystyrene and polybutadiene films. Thus, dewetting inhibition by nanoparticles appears to be a general effect, although certain conditions apparently need to be met for its occurrence. Specifically, a general tendency for the particles to segregate to the solid substrate seems to be required and the interaction between the particles and polymer must not be too unfavorable. The phase boundaries of the dendrimer−polymer mixtures depend on the generation, the high...

The intrinsic viscosity of narrow molecular mass distribution polystyrene standards, poly(benzyl) ether dendrimers, and their hybrid block copolymers was measured in a variety of solvents. The relative change in the intrinsic viscosity for all these polymers was almost equivalent, indicating that poly(benzyl ether) dendrimers expand and contract quite readily with a change in solvent. The intrinsic viscosity maximum for all polymers was found to occur at essentially the same solvent solubility parameter demonstrating that the thermodynamic interaction with the selected range of solvents was also equivalent. The intrinsic viscosity for hybrid copolymers in a good solvent for both components was found to fall well below the intrinsic viscosity for neat polystyrene at intermediate molecular masses. Below and above this mass range the intrinsic viscosity was quite similar to polystyrene. Yet, the transition for intermediate to high molecular mass behavior was quite sharp as seen through a rapid intrinsic visc...