DOI: 10.1140/epje/e2003-00008-y
Association behavior of polyisoprenes having cholesterol and phosphatidylcholine analogous end groups
K. Kostakis, S. Mourmouris, D. Charalabidis and M. PitsikalisDepartment of Chemistry, University of Athens, Panepistimiopolis Zografou, 15771 Athens, Greece pitsikalis@chem.uoa.gr
(Received 29 April 2002 and Received in final form 13 November 2002 Published online: 11 March 2003 )
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,
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
values. The
hydrodynamic behavior of the aggregates was similar to that of star polymers. The
dependence of the
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.
82.30.Nr - Association, addition, insertion, cluster formation.
61.30.Vx - Polymer liquid crystals.
82.35.-x - Polymers: properties; reactions; polymerization .
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2003
