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Synthesis and pH- and salinity-controlled self-assembly of novel amphiphilic block-gradient copolymers of styrene and acrylic acidстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
- Авторы: Borisova O.a.b, Billon L.a., Zaremski M.b., Grassl B.a., Bakaeva Z.c., Lapp A.d., Stepanek P.c., Borisov O.a.
- Журнал: Soft Matter
- Том: 8
- Номер: 29
- Год издания: 2012
- Издательство: Royal Society of Chemistry
- Местоположение издательства: United Kingdom
- Первая страница: 3649
- Последняя страница: 3659
- DOI: 10.1039/c2sm25625h
- Аннотация: A novel type of amphiphilic ionic copolymer comprising a hydrophilic poly(acrylic acid) (PAA) block and an amphiphilic poly(acrylic acid)-grad-poly(styrene) (PAA-grad-PS) copolymer block was synthesized using a one step direct nitroxide-mediated polymerization (NMP). A strong influence of the macroinitiator on the values of the reactivity ratios of the co-monomers is confirmed by 1H NMR. The aggregation behaviour of the copolymers in the aqueous medium was studied by small-angle neutron scattering (SANS) and dynamic light scattering (DLS) and by transmission electron microscopy (TEM) in a wide range of pHs and ionic strengths. It has been demonstrated that PAA-b-(PAA-grad-PS) copolymers are soluble in alkaline water at room temperature without the special experimental procedures (addition of co-solvent, heating, etc.) that are usually required for solubilisation of classical PAA-b-PS diblock copolymers. The self-assembly of the PAA-b-(PAA-grad-PS) copolymers into nano-scale aggregates at low/moderate pH and/or high ionic strength was demonstrated by SANS and DLS experiments. The SANS spectra for the copolymer solution exhibit a correlation peak pointing to the formation of micelles with repulsive coronae. TEM images indicate that the micelles have an approximately spherical shape and exhibit a wide size distribution. Our results prove, that in contrast to "frozen" aggregates formed by PAA-b-PS copolymers in aqueous media, the micelles of PAA-b-(PAA-grad-PS) amphiphilic copolymers exhibit "dynamic" pH-responsive properties, i.e. they can reversibly change their aggregation number upon a variation in the pH or salinity of the solution. © 2012 The Royal Society of Chemistry.
- Добавил в систему: Заремский Михаил Юрьевич