Model macromolecules

Abstract

The interest for tailor-made macromolecules arises from their use as calibration samples for characterization techniques, and from their prominent role in the investigations of structure/properties relationships. The conditions most appropriate for the synthesis of model macromolecules of various kinds are reviewed. Two cases of controlled polymer synthesis are considered in greater detail : Cyclic macromolecules and star shaped polymers

Cyclic Polymers by Ring‐Closure Strategies

“…Fractionation was,therefore,required to isolate the macrocycles from linear impurities.C yclic polymers with diverse polymer backbones (poly(2-vinylpyridine) (P2VP), polybutadiene,poly(isoprene) (PI), poly(dimethylsiloxane) (PDMS), and poly(propylene oxide) (PPO)) were prepared by using dianionic linear precursors in combination with bifunctional coupling agents. [28][29][30][31] An interesting variant was reported by Ishizu and Kanno where each chain end of ad ianionic PS (number-average molecular weight (M n ) = 7000 gmol À1 )w as capped in af irst step with 1,4-dibromobutane,w hich was added in excess, and then cyclized by reaction with ad iamine in abiphasic system, thereby allowing the intermolecular oligomerizations to be minimized (Scheme 2). Cyclization yields of more than 80-90 %w ere achieved, thus preventing the need for extensive purification procedures.…”

Cationic Polymerization Astronomy. Synthesis of Polymer Stars by Cationic Means

“…54 The fact that the arms radiate from a relatively small common core increases the segment density distribution and reduces the coil dimensions relative to those of linear chains of the same molecular weight. [73][74][75][76] Stars due to their branched structure have higher segment densities and consequently smaller polymer coil dimensions than linear polymers of the same molecular weight. [73][74][75][76] Hence, the hydrodynamic volume of stars are much lower than those of linear chains of the same molecular weight.…”

“…[73][74][75][76] Stars due to their branched structure have higher segment densities and consequently smaller polymer coil dimensions than linear polymers of the same molecular weight. [73][74][75][76] Hence, the hydrodynamic volume of stars are much lower than those of linear chains of the same molecular weight.…”

“…The viscosity of stars depends mainly on the arm molecular weight and much less on the number of arms or the molecular weight of the star − Stars due to their branched structure have higher segment densities and consequently smaller polymer coil dimensions than linear polymers of the same molecular weight. − Hence, the hydrodynamic volume of stars are much lower than those of linear chains of the same molecular weight. …”