RESUMEN
Free radical polymerization of ethylene in an intermediate pressure and temperature range (P(ethylene) < 250 bar and 50 °C < T < 90 °C) in the presence of an organic solvent has been studied. Under selected conditions (P, T) and according to the amount of organic solvent added, either a supercritical monophasic or a biphasic medium is obtained. In the case of a biphasic medium, polymerization occurred in the liquid phase in which radical initiator and ethylenes are dissolved. The transition between a monophasic to a biphasic medium has been predicted using thermodynamic calculations and has been related to experimental observations such as the dependence of polymerization activity versus solvent volume.
RESUMEN
Biomolecule-polymer conjugates are widely used in bio-related fields, but their synthesis is often tricky, especially the introduction of a single biomolecule at one chain end. This paper describes a new straightforward approach to prepare such conjugates via RAFT polymerization. By designing appropriate bio-related RAFT agents, polymer chains of controlled chain length (Mn = 10 000-40 000 and PDI < 1.1) carrying a single biomolecule as an alpha-end group (a sugar or a biotin) linked by a stable amide bond are obtained. Considering the versatility of the RAFT process, this strategy appears to be very attractive for the design of a variety of conjugates.