Poly(methyl methacrylate)s of extremely high molecular weights (>106) and narrow molecular weight distributions (M̄w/M̄n<1.2:1) were easily obtained by living/controlled free‐radical polymerization under high hydrostatic pressure (5 kbar; see scheme, AIBN=2,2′‐azobis(isobutyronitrile)). This technique provides conditions amenable to industrial scale‐up.

Telechelic high molecular weight polystyrene (PS-A) and poly(methyl methacrylate) (PMMA-A) containing anthracene end groups undergo end-coupling reaction in THF solution to form [4 + 4] anthracene photodimers upon exposure to UV irradiation at wavelengths greater than 300 nm. A mixture of products is obtained that include the coupled polystyrene homopolymer, P(S-AA-S), coupled PMMA homopolymer, P(MMA-AA-MMA), and the desired diblock copolymer, P(S-AA-MMA). The polymer concentration and molecular weights have a direct influence on the photoreaction kinetics but do not affect the molar ratio of the three polymeric products. P(S-AA-MMA), purified by extraction of the homopolymers with selective solvents, exhibits thermal cleavage of the junction points and reversion back to homopolymers at temperatures at or above 135°C. AFM images of thin films of P(S-AA-MMA) spin-coated onto passivated silicon substrates show a microphase-separated cylindrical microdomain morphology with the cylinders oriented normal to the surface.

Reinvestigation of Strychnos icaja Baillon resulted in the isolation of vomicine, isostrychnine and of three new sungucine derivatives, named isosungucine (8), 18-hydroxy-sungucine (9) and 18-hydroxy-isosungucine (10). They were identified by detailed spectroscopic methods. The complete 1H- and 13C-NMR study of sungucine was also realized. Some of these compounds were highly active against Plasmodium falciparum in vitro and more particularly against the chloroquine-resistant strain. Compound 10 showed a selective antiplasmodial activity, with > 100-fold greater toxicity towards Plasmodium falciparum, relative to cultured human cancer cells (KB and HeLa lines) or fibroblasts (WI38).

The crystalline packing and the phase structure of a long-chain aliphatic polyester, (O(CH 2 ) 22 -OOCCH 2 CH 2 CO) n , PE22,4, have been studied in molecular detail by small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WAXD) experiments as well as various solid-state nuclear magnetic resonance (NMR) methods, in particular two-dimensional double-quantum spectroscopy (DOQSY) NMR. The volume crystallinity is 73 ( 3% according to quantitative 13 C NMR and SAXS analyses. The DOQSY NMR spectra show signal characteristic of trans ester groups incorporated into straight poly(methylene) chains, as expected on the basis of WAXD. DOQSY spectra of singly 13 COO-labeled diesters prove close proximity of ester groups in neighboring chains, confirming the ester layering deduced from SAXS, with three diester layers per crystallite. SAXS shows a 37°chain tilt with respect to the diester layers and crystallite surface, and the DOQSY NMR spectra confirm the resulting significant displacement of ester groups along neighboring chains. The data suggest a R 22 tilting of the chain axes. NMR detects no significant disorder along the chain axes; this suggests that the disappearance of (h, k, l * 0) reflections in WAXD is due to the small crystallite thickness, which is 5.6 ( 0.5 nm according to SAXS. The DOQSY NMR patterns show that the planes of the chains are far from the perpendicular relative orientation found in orthorhombic polyethylene, constraining the angle between the (normals to the) O-CdO ester planes to 55°( 20°. DOQSY NMR also indicates that ∼1/3 of the COO groups directly at the crystalline-amorphous interface are disordered. The chain loops in the amorphous phase contain only 6% of the esters and thus mostly consist of the C 22 polymethylene section of one C 26 repeat unit. The C 22 loops connect ∼71% of the ends of crystalline stems, while 9% are terminated by chain ends and 20% are connected to a loose loop or tie molecule. NMR relaxation measurements confirm that, in spite of the relatively small fraction of ester groups among the poly(methylene) chains, they strongly suppress the fast 180°chain flips observed in polyethylene crystallites.

Stimuli-responsive amphiphilic block copolymers have emerged as promising nanocarriers for enhancing site-specific and on-demand drug release in response to a range of stimuli such as pH, the presence of redox...