title: Association behavior of polyisoprenes having cholesterol and phosphatidylcholine analogous end groups.
abstract: Linear polyisoprenes having dimethylamine end groups were prepared by high vacuum anionic polymerization techniques using 3-dimethylaminopropyllithium as the initiator. The amine group was reacted with 2-cholesteryl-2-oxo-1,3,2-dioxaphospholane to provide polymer chains having end zwitterionic groups chemically connected with cholesterol. The association behavior of these end-functionalized polymers was studied in cyclohexane by low angle laser light scattering, dynamic light scattering, and viscometry. The aggregation numbers, Nw were found to decrease by increasing the molecular weight of the precursor polymer, due to excluded volume repulsions. The ability of cholesterol to form liquid crystal mesophases facilitated the association process leading to higher Nw values. The hydrodynamic behavior of the aggregates was similar to that of star polymers. The dependence of the Nw values on the molecular weight of the base polymer, the polydispersity of the associates and the absence of critical micelle concentration, cmc are compatible with the linear head-packing model.
authors.affiliation: Department of Chemistry, University of Athens, Panepistimiopolis Zografou, 15771 Athens, Greece.
authors.forename: K
authors.initials: K
authors.lastname: Kostakis
authors.forename: S
authors.initials: S
authors.lastname: Mourmouris
authors.forename: D
authors.initials: D
authors.lastname: Charalabidis
authors.forename: M
authors.initials: M
authors.lastname: Pitsikalis
mesh_terms: D040761:Biomimetic Materials / Q000138:chemical synthesis / Q000737:chemistry*; D002070:Butadienes / Q000737:chemistry*; D002784:Cholesterol / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D003510:Cyclohexanes / Q000737:chemistry*; D045782:Hemiterpenes / Q000737:chemistry*; D046911:Macromolecular Substances; D008666:Metalloendopeptidases; D008968:Molecular Conformation; D008970:Molecular Weight; D010420:Pentanes / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*; D012997:Solvents / Q000737:chemistry
chemical_list: D002070:Butadienes; D003510:Cyclohexanes; D045782:Hemiterpenes; D046911:Macromolecular Substances; D010420:Pentanes; D010713:Phosphatidylcholines; D011108:Polymers; D012997:Solvents; C005059:isoprene; D002784:Cholesterol; D008666:Metalloendopeptidases; C477817:molecule metalloprotease-related protein-1, human