@article{GarnierLaschewsky2005, author = {Garnier, Sebastien and Laschewsky, Andr{\´e}}, title = {Synthesis of new amphiphilic diblock copolymers and their self-assembly in aqueous solution}, year = {2005}, abstract = {Amphiphilic diblock copolymers composed of poly(butyl acrylate) as the hydrophobic block with a low glass transition temperature and of six different hydrophilic blocks (one anionic, one cationic, and four nonionic hydrophilic blocks) are prepared via reversible addition fragmentation chain transfer (RAFT) polymerization. The nonionic hydrophilic blocks comprise in addition to the classical poly(dimethylacrylamide), the thermally sensitive poly(N- acryloylpyrrolidine), and a comb-type polymer made of a poly(ethylene glycol acrylate) macromonomer, as well as a new strongly hydrophilic sulfoxide polymer. The "living" character of the polymerizations is supported by very low polydispersity indexes and a good correlation between the molar masses obtained and the theoretically expected ones. Two distinct glass transition temperatures were found by differential scanning calorimetry for the block copolymers, suggesting the immiscibility of the blocks in bulk. The self-assembling properties of the amphiphilic diblock copolymers in aqueous and organic media were studied by nuclear magnetic resonance spectroscopy and dynamic light scattering, as a function of the polarity of the hydrophilic blocks, the ratio of the lengths of the two blocks, and the overall molar mass of the diblock copolymers. Micellelike aggregates with diameters from 25 to 100 mn in water are found, as well as inverse micelles in organic solvents. The length of the hydrophobic block seems to be the main factor governing the size of the aggregates in water. The aggregates are very stable upon dilution and temperature cycles. For large hydrophobic blocks, big structures are observed in addition to small micelles initially after the dispersion in water. As the big aggregates disappear slowly, the micellization process seems thermodynamically favored. If two populations of micelles made from different block copolymers are brought together, "mixed" micelles are formed. The implicit exchange of polymers proves the dynamic character of the micellar systems based on poly(butyl acrylate) as hydrophobic block}, language = {en} } @article{MertogluGarnierLaschewskyetal.2005, author = {Mertoglu, Murat and Garnier, Sebastien and Laschewsky, Andr{\´e} and Skrabania, Katja and Storsberg, J.}, title = {Stimuli responsive amphiphilic block copolymers for aqueous media synthesised via reversible addition fragmentation chain transfer polymerisation (RAFT)}, issn = {0032-3861}, year = {2005}, abstract = {A series of RAFT agents was synthesised, and used to prepare various ionic. non-ionic and zwitterionic water- soluble polymers, in organic as well as in aqueous media. The RAFT process proved to be a powerful method to prepare functional polymers of complex structure. such as amphiphilic diblock and triblock copolymers. This includes polymers containing one or even two stimuli-sensitive hydrophilic blocks. Switching the hydrophilic character of a single or of several blocks by changing the PH, the temperature or the salt content demonstrated the variability of the molecular designs suited for stimuli-sensitive polymeric amphiphiles, and exemplified the concept of multiple-sensitive systems. (c) 2005 Published by Elsevier Ltd}, language = {en} }