| Poly(N-isopropylacrylamide) (PNIPAm) in aqueous solution is wellknown to exhibit a thermoreversible phase transition at 32 "C. This transition temperature is called a lower critical solution temperature (LCST). Below the LCST, this polymer is water-soluble and hydrophilic, existing in an extended chain form. PNIPAm undergoes a reversible phase transition to an insoluble and hydrophobic aggregate above the LCST. This character of PNIPAm has been widely used in the field of biological and medical science, such as the stability of enzyme, temperature control drug release, hi this thesis, it meanly discussed the synthesis of the same two alkyl groups of different chain lengths (Ci2 and CM) to one end of PNIPAm, their water solution characters, the affecting of the hydrophobic chain length of PNIPAm to the polymeric aggregation and incorporation of the polar monomer with PNIPAm chains adjusting the LCST and so oaA-B type block copolymers comprising both hydrophilic and hydrophobic segments can form core-shell heterogeneous ordered micellar structure in aqueous media as a result of their amphiphilic character. Block copolymer micellers form with a hydrophilic outer shell and a hydrophobic inner core by inter and intramolecular association of hydrophobic segments. The hydrophobic inner core is surrounded and stabilized by the hydrophilic outer shell, so it can solubilize hydrophobic molecules, such as drug molecules, due to its apolar microenvironment This heterogeneous ordered structure presents opportunities to construct highly functionalized drug carrier systems. So hydrophobic drug molecular can be carried by micellar inner core in water solution. A highly hydrated polymeric micelle outer shell can inhibit intermicellar aggregation of the hydrophobic inner cores and proper polymeric micelle size ranges (<100nm) can inhibit non-selective scavenging by the reticuloendothelial system(RES),therefore, can be used to carry drug to the target.AB-type block copolymers consisting of a PNIPAm segment and a hydrophobic segment not only have the character of the ordinary micelles, but also have temperature-responsive phase transition. With the temperature control at particular sites, drug release can be controlled only for a time period defined by local heating and cooling.Amino-terminated PNIPAm (P-NH2( I )) (molecular weight about 5600) were prepared by radical polymerization using AESH 籋C1 as chain transfer agent. In order to contrast to the affecting of the hydrophobic segment chain length to PNIPAm, alkyl-terminated PNIPAm ,PNG-12 ( I ) or PNG-14( I ), was obtained by a condensation reaction between the terminal carboxylic end group of glu-12-M or glu-14-M (prepared by ourselves) and the primary amino group of P-NH2( I ).These amphiphilic PNIPAm polymers consisting of the same two alkyl chains and one pure PNIPAm chain are like lipids molecules. As a result, their aqueous solution showed the same LCST as pure PNIPAm with Ultraviolet-Visible light spectrometer. TEM and Fluorescence spectra were all showed PNG-12( I ) and PNG-14( I ) could form core-shell micelle-like aggregation structure above one concentration by self-assembly of the modified PNIPAm at ambient temperature. But with concentration increase, the micelles would aggregate and form compounding micelles consisting of a few hydrophilic and hydrophobic microdomains. This structure has potential value to drug carrier system.In order to discuss the effect of the ratio of hydrophilic/hydrophobic chain length to polymeric aggregations in water, we synthetised three kinds of molecular weight PNIPAm (P-NH2(II), P-NH2 (III), P-NH2 (IV) ), and obtained four kinds of alkyl-terminatedPNIPAm(PNG-14 (II), PNG-14 (III), PNG-14 (IV) andPNG-12 (IV) ). The results showed the chain length of pure PNIPAm affected modified PNIPAm temperature-sensitivity and aggregation structure . When the hydrophilicchains are short, the polar interaction will be too weak to against the aggregating of hydrophobia segment, leading to form non-isolated microdomains.The...
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