Stars and Blocks: Tailoring Polymeric Rheology Modifiers for Aqueous Media by Controlled Free Radical Polymerization

Thermoresponsive Self-Assembly of Twofold Fluorescently Labeled Block Copolymers in Aqueous Solution and Microemulsions

“…Because of the inherently reduced mixing entropy and the resulting strong tendency for (micro)­phase separation and by virtue of the substantially increased number of molecular variables in comparison to low-molar-mass surfactants, polymeric amphiphiles give rise to a plethora of self-organized structures in selective solvents, in particular, in aqueous media. − Two major polymer classes are conveniently distinguished according to the origin of the amphiphilic character. On the one hand, the constitutional monomer units (CRU), or at least short monomer sequences, are inherently amphiphilic, as in the so-called polysoaps. − On the other hand, amphiphilicity can result from the overall macromolecular architecture that combines individual hydrophobic and hydrophilic blocks, as in amphiphilic graft and block copolymers (“macro surfactants”). ,, While formerly, amphiphilic block copolymers were restricted to a small number of practical systems, the advent of the reversible deactivation radical polymerization (RDRP) methods has diversified the synthesis of block copolymers exceedingly and concomitantly the investigation and use of the latter copolymer class enormously during the past two decades. − A particular aspect of amphiphilic block copolymers is the relative ease of implementing responsive (also called “smart” or “intelligent”) amphiphilic systems, which react to a small change in a trigger parameter with important changes in their self-assembly behavior and thus their properties. − Arguably, the most explored trigger is a temperature change because it is noninvasive and the induced changes are fully reversible in many cases, thus enabling repeated switching of such systems. In aqueous systems, thermoresponsive polymers typically exploit the crossing of a lower consolute boundary and are characterized by a lower critical solution temperature (LCST).…”

“…13 C NMR(75 MHz in CDCl 3 , δ in ppm): δ = 14.22 (ESI: calculated mass M r = 819.10 g/mol; found: 841.64 g/mol [M + Na] + . FTIR (selected bands, cm −1 ): 2924, 2852, 1730, 1693, 1653, 1612, 1585, 1514, 1466, 1452, 1387, 1369, 1354, 1292, 1281, 1263, 1240, 1201, 1147, 1068, 1024, 1016, 872, 849, 833, 816, 781, 760, 735, 706.…”

Exploring Poly(ethylene glycol)-Polyzwitterion Diblock Copolymers as Biocompatible Smart Macrosurfactants Featuring UCST-Phase Behavior in Normal Saline Solution

“…In this way, the amphiphilic character, and thus the self-assembly of the block copolymers, can be deliberately switched “on” and “off”. Furthermore, such a responsive aggregation behavior enables control of the system’s viscosity [ 16 , 17 , 18 , 19 ], as well as the transport and controlled delivery of poorly water-soluble active agents [ 20 , 21 , 22 ] ( Scheme 1 ).…”

Polymeric Drift Control Adjuvants for Agricultural Spraying

“…[7] Additionally, these rheology-modifying additives have application in other areas including enhanced oil recovery (EOR), [8] drag reduction in pipelines, [9] cosmetics and inkjet printing. [10,11] The enhanced extensional viscosity (or elasticity) of polymer solutions is believed to cause the larger drop size. [12] Increases in other rheological properties such as dynamic surface tension, [3,13] and to a lesser extent static surface tension and zero shear rate viscosity have also been reported to increase spray drop size.…”

“…While droplet size is predominantly affected by nozzle selection, polymer adjuvants used in dilute concentration can also strongly affect droplet size and jet breakup . Additionally, these rheology‐modifying additives have application in other areas including enhanced oil recovery (EOR), drag reduction in pipelines, cosmetics and inkjet printing . The enhanced extensional viscosity (or elasticity) of polymer solutions is believed to cause the larger drop size .…”