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Model linear and star‐shaped polyisoprenes with phosphatidylcholine analogous end‐groups. Synthesis and association behavior in cyclohexane
Author(s) -
Charalabidis David,
Pitsikalis Marinos,
Hadjichristidis Nikos
Publication year - 2002
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/1521-3935(200210)203:14<2132::aid-macp2132>3.0.co;2-x
Subject(s) - cyclohexane , intermolecular force , chemistry , dynamic light scattering , polymer chemistry , intramolecular force , end group , anionic addition polymerization , polymerization , molecule , stereochemistry , materials science , organic chemistry , polymer , nanotechnology , nanoparticle
Semitelechelic ( ω ‐), telechelic ( α , ω ‐), as well as 3‐ and 12‐arm star polyisoprenes (PI), end‐functionalized with the same dimethylamino group, were synthesized by anionic polymerization high vacuum techniques, using 3‐dimethylaminopropyllithium as initiator and chlorosilanes as linking agents. The dimethylamino groups were transformed to phosphatidylcholine analogues through reaction with 2‐ethoxy‐2‐oxo‐1,3,2‐dioxaphospholane. The association behavior of the phosphoro‐zwitterionic PI (PZw‐PI) was studied in cyclohexane by low angle laser light scattering, viscometry, and dynamic light scattering. The linear PZw‐PIs present relatively low weight‐average degree of association ( N w : 2–6), as compared with the corresponding sulfo‐zwitterionic PI ( N w : 10–45). The N w values decrease with increasing molecular weight of the PI. In the case of the star PZw‐PI, the multiple intermolecular associations lead to the formation of gels, which break down by addition of a small amount of 1‐heptanol. In very dilute solutions and for high arm molecular weight stars, intramolecular dominates over intermolecular association.