Coplanarity by hydrogen bonding in well-defined oligoheterocycles

(Hetero)aryl-aryl coupling for covalent bonding and intramol. hydrogen bond formation for establishing the secondary structure have been united to design and construct well-defined, functionalized macromols. The suitability of azaheterocyclic units to realize this concept is exemplified by star shaped discotic liq. cryst. compds. and ladder-type conjugated copolymers. A review with >40 ref

pi-Conjugated oligomers and polymers with a self-assembled ladder-like structure

A series of alternating polymers and well-defined oligomers, composed of 2,5-linked pyrazines and N,N'-diacylated phenylene-1,4-diamines were prepd. using the Stille cross-coupling. The presence of N-hydrogen bond acceptors and N-hydrogen bond donors in adjacent units induces intramol. hydrogen bonding and hence leads to spontaneous formation of a ladder-type structure in which the arylene units tend to become coplanar. Self-assembly of the ladder structure in soln. is convincingly demonstrated by NRM- and IR-spectroscopy. The acylation of the ortho-amine functionalities with lipophilic groups leads to strong hydrogen bonding and improve soly. These large ortho-substituents do not disturb the p-delocalization of the syste

Polystyrene-dendrimer amphiphilic block copolymers with a generation-dependent aggregation

Contains fulltext : 17220.pdf (publisher's version ) (Open Access

Polystyrene-poly(propylene imine) dendrimer block copolymers: a new class of amphiphiles

Contains fulltext : 17213.pdf (publisher's version ) (Open Access

Encapsulated material with controlled release

An encapsulated material is described of which at least a part of the material is kept encapsulated during heat treatment in an aqueous environment and is released during cooling after a heat treatment. The material is encapsulated in a layer of a hydrophobic film-forming material and a layer of a material having a low critical solution temperature (LCST) below the treatment temperature. The layer containing the hydrophobic material may be situated inside the layer having the LCST and have a melting point below the LCST, but it may also be situated outside the layer having the LCST and have a melting point above the LCST of said layer. Said layers may also be applied together

Encapsulated material with controlled release

An encapsulated material is described of which at least a part of the material is kept encapsulated during heat treatment in an aqueous environment and is released during cooling after a heat treatment. The material is encapsulated in a layer of a hydrophobic film-forming material and a layer of a material having a low critical solution temperature (LCST) below the treatment temperature. The layer containing the hydrophobic material may be situated inside the layer having the LCST and have a melting point below the LCST, but it may also be situated outside the layer having the LCST and have a melting point above the LCST of said layer. Said layers may also be applied together