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Synthesis, characterisation and evaluation of novel methacrylatebased water-soluble block copolymers

Başlık çevirisi mevcut değil.

  1. Tez No: 400431
  2. Yazar: VURAL BÜTÜN
  3. Danışmanlar: STEVE ARMES
  4. Tez Türü: Doktora
  5. Konular: Metalurji Mühendisliği, Metallurgical Engineering
  6. Anahtar Kelimeler: Belirtilmemiş.
  7. Yıl: 1999
  8. Dil: İngilizce
  9. Üniversite: Unıversıty Of Sussex
  10. Enstitü: Yurtdışı Enstitü
  11. Ana Bilim Dalı: Malzeme Bilimi ve Mühendisliği Ana Bilim Dalı
  12. Bilim Dalı: Belirtilmemiş.
  13. Sayfa Sayısı: Belirtilmemiş.

Özet

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Özet (Çeviri)

Group transfer polymerisation has been used to prepare a series of water-soluble (co)polymers ofnarrow molecular weight distribution based on tertiary amine methacrylates. 2-(dimethylamino)ethyl methacrylate (DMA) was block copolymerised in turn with three other tertiary aminemethacrylate comonomers, namely 2-(diethylamino)ethyl methacrylate (DEA), 2-(diisopropylamino)ethyl methacrylate (DPA) and 2-(N-morpholino)ethyl methacrylate (MEMA). A series ofdiblock copolymers, DMA-MEMA, DMA-DEA and DMA-DPA, with molecular weightsranging from 1x103 g mol-1 to 5x104 g mol-1 and with DMA contents varying systematically from20 to 80 mol % were synthesized. In order to obtain block copolymers of suitable composition,and hence micellisation behaviour, a series of each homopolymers were also synthesized andtheir solubility in water investigated. All homopolymers and block copolymers had narrowmolecular weight distributions (Mw/Mn<1.2), which is typical for GTP (co)polymers. DMA andMEMA homopolymers were both water-soluble at 20oC around neutral pH, but became insolubleat higher temperatures, with cloud-points ranging from 32 to 47oC. Cloud points decreasedmonotonically with increasing degrees of polymerisation, as expected. The MEMAhomopolymers were particularly sensitive to added electrolyte, with `salting out? occurring at20oC on addition of 0.2-0.3 M Na2SO4. The more hydrophobic DEA and DPA homopolymerswere both insoluble at 20oC and neutral pH but readily dissolved as cationic polyelectrolytes inacidic media due to protonation of the tertiary amine residues. All the (co)polymers dissolveddirectly into neutral or acidic water at room temperature without using co-solvents. Subtledifferences in basicity between the two blocks led to interesting aqueous solution behaviour,including pH-, temperature- and salt-induced micellisation, very high surface activity and tunablesolubility depending on both solution temperature and pH. Micellisation was fully reversible andin all cases stable micelles with DMA coronas and hydrodynamic diameters of 20-60 nm wereformed. Moreover, it has also been demonstrated for the first time that an AB diblock copolymer(DEA-MEMA) can aggregate reversibly to form micelles in which either the A block or the Bblock forms the non solvated micellar core in aqueous media at 20oC. This behaviour has neverbeen previously reported for any block copolymer or surfactant.Selective quaternisation of the DMA residues in the block copolymers was achieved with methyliodide, benzyl chloride or 1,3 propane sultone and the micellisation behaviour of the derivatisedcopolymers has been studied. In all cases, the quaternised DMA block formed the solvatedmicelle coronas and the other block (DPA, DEA, MEMA) formed the micelle cores.Shell cross-linked micelles (SCK) were prepared using selected block copolymers by reactionwith a bifunctional quaternising agent in aqueous solution. Proton NMR studies confirmed thatthe SCK micelle cores can be reversibly hydrated or dehydrated, depending on the solutiontemperature and the electrolyte concentration. In addition, novel zwitterionic SCK micelles havealso been prepared from DMA-THPMA copolymers in aqueous media. Depending on thereaction conditions used, two classes of SCK were obtained, with either cationic or anionic coresrespectively. Both types of SCK micelles exhibited isoelectric points in aqueous solution. Theaqueous solution properties of the (co)polymers and SCK micelles have been investigated usingturbidimetry, 1H NMR spectroscopy, dynamic and static light scattering, transmission electronmicroscopy and surface tensiometry.

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