Patent ID: 7316816

Claim:
An amphiphilic copolymer comprising at least three types of monomeric units, said three types of monomeric units comprising: a temperature-sensitive monomeric unit, a hydrophilic monomeric unit, wherein the hydrophilic monomeric unit has one or more polar functionalities, and a hydrophobic monomeric unit comprising at least one pH-sensitive moiety; wherein said hydrophobic monomeric unit is derived from a copolymerisable unsaturated fatty acid, wherein said unsaturated fatty acid imparts hydrophobic character to the copolymer; wherein the copolymer has a lower critical solution temperature (LCST) dependent on environmental pH; wherein said lower critical solution temperature (LCST) decreases as pH decreases; wherein the fatty acid comprises 5 to 50 or more main chain carbon atoms; and wherein the fatty acid comprises at least 2 carbon-carbon double bonds (polyunsaturated).