Model ω‐Functionalized Linear Polystyrenes with One, Two, and Three Sulfobetaine End Groups: Synthesis, Characterization, and Association Behavior

Abstract

Three series of ω‐functionalized polystyrenes (PS) with different molecular weights, the first consisting of dimethylamino end‐capped PSs and the other two of ω‐branched PSs end‐capped with two and three low‐molecular‐weight (Mn ∼ 500 g · mol−1) dimethylamino ω‐functionalized polybutadienes (PB), were synthesized by high‐vacuum anionic polymerization techniques using the functional initiator ([3‐(dimethylaminopropyl)]lithium) and chlorosilane linking chemistry. The ω‐dimethylamino polymers (precursors) were molecularly characterized by size‐exclusion chromatography, low‐angle laser light scattering (LALLS), membrane osmometry, and NMR spectroscopy. The characterization results indicate a high degree of molecular and structural homogeneity. The dimethylamino end groups were transformed to the highly polar sulfozwitterionic ones (see Figure) by reaction with cyclopropanosultone. The mono‐, di‐, and tri‐zwitterion capped polymers were found by LALLS, dynamic light scattering (DLS) and viscometry, to associate in carbon tetrachloride, a good nonpolar solvent for the PS tail. In contrast, results on dimethylamino‐capped precursors show no evidence of aggregation. Aggregation numbers increase in decalin compared with those in carbon tetrachloride. At constant molecular weight of the parental PS, the degree of association increases with increasing number of functional groups and for a given number of functional groups with decreasing molecular weight of the PS tail. Temperature‐dependent light scattering measurements in decalin indicate that aggregation persists at the highest temperature investigated.A schematic representation of the materials investigated in this study.magnified imageA schematic representation of the materials investigated in this study.

Neutron Reflectivity and Computer Simulation Studies of Self-Assembled Brushes Formed by Centrally Adsorbed Star Polymers

“…Polymer brushes can be grown chemically from a surface or can be formed by block copolymer self-assembly procedures where one block dissolves in the solvent and the other block adsorbs on a surface. Self-assembled brushes of end-functionalized polystyrene (PS) with a short anchor block have been prepared in the case where the anchor block is either a small polymer chain such as poly(ethylene oxide) (PEO) or a small molecule such as a sulfozwitterionic end group …”

Synthesis and Characterization of Star-Shaped Poly(ethylene-co-propylene) Polymers Bearing Terminal Self-Complementary Multiple Hydrogen-Bonding Sites

“…Although both functional polymers and star-shaped polymers are prevalent in the literature, the combination of well-defined thermoreversible chain-end interactions, such as multiple hydrogen-bonding interactions, and star-shaped macromolecules is limited. Hadjichristidis et al studied the synthesis and characterization of well-defined linear and star-shaped polystyrenes, polyisoprenes, and polybutadienes bearing sulfo- and phosphoro-zwitterionic groups capable of thermoreversible association. − Although these studies contributed significantly to the understanding of structure−property relationships, the reversible interaction is electrostatic, and the behavior of polymers that interact through multiple hydrogen bonding is expected to differ significantly. Meijer et al recently reported the synthesis of model low-molecular-weight poly(ethylene oxide- co -propylene oxide) three-arm star-shaped polymers with pendant 2-ureido-4[1 H ]-pyrimidinone (UPy) quadruple hydrogen-bonding functionalities .…”

Adsorption of star polymers studied by a new numerical mean field theory

“…The first consisted of a dimethylamino endcapped polystyrene (PS) chain (70K molecular weight) and the other two of u-branched PS chains (70K molecular weight) end-capped with low-molecular-weight (M n w500 g=mol) dimethylamino polybutadienes (PB). These macromolecules were synthesized by high-vacuum anionic polymerization techniques [38] and studied with Neutron Reflectivity [39]. The solvent was toluene which is considered a good solvent for PS.…”