End-Functionalized Block Copolymers of Styrene and Isoprene: Synthesis and Association Behavior in Dilute Solution

Abstract

The dilute solution properties of di-and triblock copolymers of isoprene and styrene having a highly polar sulfozwitterion group on one or both ends of the chain were studied in the nonpolar solvent carbon tetrachloride (a good solvent for polystyrene and polyisoprene) by low-angle laser light scattering. The copolymers were prepared by anionic polymerization using high-vacuum techniques with [3-(dimethylamino)propyl]lithiumas initiator. The dimethylamino end group of the chain was transformedtoa zwitterion by reaction with cyclopropanesultone. The monofunctional zwitterion-capped copolymers were found to associate in carbon tetrachloride, whereas the difunctional versions formed gels even below the coil overlap concentration, c*. The aggregation number was found to decrease with increasing base molecular weight due to the excluded volume repulsions of the copolymeric tails. Comparison with the corresponding o-zwitterionic polyisoprene homopolymers in cyclohexane and in carbon tetrachloride shows that for the same base molecular weight the materials with the homopolymeric tails aggregate more strongly. Aggregation numbers for the copolymers are of the same order of magnitude as the degree of association measured for a zwitterion-capped polystyrene. The presence of the phenyl rings in the copolymer chain seems toreduce the extent of aggregation. The effect of position and number of the functional groups on the strength of the association is also discussed.

Model linear and star-shaped polyisoprenes with phosphatidylcholine analogous end-groups. Synthesis and association behavior in cyclohexane

“…of isoprene and styrene [14,15] and 3-arm star polybutadienes with one, two, or three SZw groups [16,17] were also studied. Evidence of strong association was found in the case of the linear chains in dilute solutions, whereas for the star polymers the association behavior depended on the number of the end-functional groups.…”

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

“…The flow rate was 1 mL Á min À1 , and the mobile phases were THF for the nonfunctionalized and dimethylamino-functionalized polymers and chloroform for the zwitterionic polymers. The latter solvent was used in order to avoid adsorption of the zwitterionic polymers on the chromatography columns [9,10] Chromatograms before and after functionalization were identical.…”

“…[6,7,25,37] A large variety of end-functionalized polymers were prepared and studied so far. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] Additionally, a number of fundamental studies aimed at the elucidation of physical phenomena like block copolymer phase behavior, polymer adsorption, adsorbed polymer brush structure, and colloid stabilization and so on were made possible through the use of end-functionalized polymers. [26][27][28][29][30][31][32][33][34][35][36] Nature, number, and position of the end groups have been varied in different ways as well as the nature of the polymeric chain.…”

End‐Functionalized Chains via Anionic Polymerization: Can the Problems with Using Diphenylethylene Derivatives be Solved by using Bisphenol F?

“…Organolithium initiators with a silyl‐protected hydroxy functionality, such as 3‐( t ‐butyldimethylsilyloxy)‐1‐propyllithium, or with acetal‐protected hydroxy functionalities, such as (6‐lithiohexyl)acetaldehyde acetal, and (3‐lithiopropyl)acetaldehyde acetal, have been used to obtain essentially quantitative hydroxy end‐functionalized polymers. Some examples of amino functionalization can also be found, in which the initiator is p ‐lithio‐ N , N ‐bis(trimethylsilyl)aniline or 3‐( N , N ‐dimethylamino)propyl‐lithium . Even though quantitative functionalization is assured with a (protected) functionalized initiator, limited availability and often limited solubility of the initiators, strongly impact on the practical application of this strategy .…”