The nanophase separation in diblock and triblock copolymers consisting of immiscible poly(n butyl acrylate) (block A) and gradient copolymers of methyl methacrylate (MMA) and n butyl acrylate (n BA) (block M/A) were investigated by means of their heat capacity, C p , as a function of the composition of the blocks M/A and temperature. In all copolymers studied, both blocks are represented by their C p and glass transition temperature, T g , as well as the broadening of the transition temperature range. The low temperature transition of the blocks A is always close to that of the pure poly(n butyl acrylate) and is independent of the analyzed compositions of the block copolymer, but broadened asymmetrically relative to the homopolymer due to the small phase size. The higher transition is related to the glass transition of the copolymer block of composition M/A. Besides the asymmetric broadening of the transition due to the phase separation, it decreases in T g and broadens, in addition, symmetrically with increasing acrylate content. The concentration gradient is not able to introduce a further phase separation with a third glass transition inside the M/A block.

Spreading of carbosilane dendrimers containing trimethylsilyl or hydroxyethyl end groups was investigated at the air/water interface. Our observations suggest that the monodisperse, globular molecules of the carbosilane dendrimer with hydroxyl end groups ordered into layers on the water surface. In contrast to the hydrophobic trimethylsilyl ends, the hydroxyl-functionalized dendrimers formed a monolayer at the air/water interface. Surface pressure versus film area isotherms were collected and showed full reversibility, irrespective of the degree of compression. Three equilibrium states of the OH-terminated dendrimer were identified depending on the molecular area. (i) The monolayer was compressible over a remarkably broad range of molecular areas from 1200 to 650 Å2. In the transition region, the osmotic pressure varied with concentration according to the power law π/kT ∼ c m with m = 15. In combination with the large monolayer thickness of (1.4 ± 0.1) nm, the steep power law indicates a globular shape for the adsorbed molecules characterized by dense packing of chain segments. (ii) In the range between 650 and 350 Å2, the dendrimer underwent a sharp transition, presumably into a bilayer structure. Since the surface pressure was almost invariant during compression, the transition is considered to be a first-order phase transition. (iii) Compression beyond 350 Å2 occurred at a constant pressure, as is typical for an isotropic liquid film. The spreading behavior of the OH-terminated dendrimer was compared with that of a polydisperse hyperbranched polymer of identical chemical composition. In contrast to the dendrimer, the hyperbranched polymer did not show any transitions and exhibited a spreading behavior similar to that of isotropic liquids.

We report studies of the collapse of monolayers of cyclolinear poly(organosiloxane)s that consist of six-membered rings joined by oxygen bridges and that contain two phenyl groups per monomer unit. Surface pressure−area isotherms show that these films undergo a stepwise collapse. The organization within the films has been examined at different stages of the collapse process by Brewster-angle microscopy. Films transferred to mica by the Langmuir−Blodgett technique have been imaged by scanning force microscopy. Five fractions of an atactic polymer with molecular weights (M W) ranging from 8900 to 85 000 and one trans-tactic polymer (M W = 8100) have been investigated. Bilayers of the fractions with the highest M W's appear in the form of islands but the bilayers in the other samples have the form of ribbons 50−250 nm wide.