Synthesis of amphiphilic block–graft copolymers [poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene)‐g‐poly(acrylic acid)] and their aggregation in water

Abstract

Novel block–graft copolymers [poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene)‐g‐poly(tert‐butyl acrylate)] were synthesized by the atom transfer radical polymerization (ATRP) of tert‐butyl acrylate (tBA) with chloromethylated poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) (SEBS) as a macromolecular initiator. The copolymers were composed of triblock SEBS as the backbone and tBA as grafts attached to the polystyrene end blocks. The macromolecular initiator (chloromethylated SEBS) was prepared by successive hydrogenation and chloromethylation of SEBS. The degree of chloromethylation, ranging from 1.6 to 36.5 mol % according to the styrene units in SEBS, was attained with adjustments in the amount of SnCl4 and the reaction time with a slight effect on the monodispersity of the starting material (SEBS). The ATRP mechanism of the copolymerization was supported by the kinetic data and the linear increase in the molecular weights of the products with conversion. The graft density was controlled with changes in the functionality of the chloromethylated SEBS. The average length of the graft chain, ranging from a few repeat units to about two hundred, was adjusted with changes in the reaction time and alterations in the initiator/catalyst/ligand molar ratio. Incomplete initiation was detected at a low conversion; moreover, for initiators with low functionality, sluggish initiation was overcome with suitable reaction conditions. The block–graft copolymers were hydrolyzed into amphiphilic ones containing poly(acrylic acid) grafts. The aggregation behavior of the amphiphilic copolymers was studied with dynamic light scattering and transmission electron microscopy, and the aggregates showed a variety of morphologies. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1253–1266, 2002

Synthesis and characterization of novel phosphonated and sulfonated poly(styrene–isobutylene–styrene) for fuel cell and protective clothing applications

“…) confirm the functionalization of SIBS. The spectra for SIBS‐CH 2 Cl show a strong band of CCl stretching at about 1260 cm −1 and bands of CH 2 twisting and rocking at about 1250 and 865, respectively . The absorption peak at 1140 cm −1 for SIBS‐g‐PVPA is assigned to the PO stretching vibration, while the band at 1000 cm −1 is assigned to POH vibration .…”

“…Chlorination, phosphonation, and sulfonation mole percentages were calculated from the EA results. Chloromethylating high quantities of SEBS increased interchain crosslinking . Therefore, three 10 g SIBS‐g‐CH 2 Cl batches were prepared to obtain the necessary material for the study (52.58, 50.85, and 51.87 mole %Cl).…”

“…SIBS was chloromethylated (i.e., SIBS‐CH 2 Cl) via a Friedel–Crafts reaction. The chloromethylation is described with more detail elsewhere . A brief description follows.…”

“…Poly(styrene‐b‐(ethylene‐co‐butene)‐b‐styrene) (SEBS) (an aromatic block copolymer similar to SIBS) has been chloromethylated in the past, yielding a material with slightly altered monodispersity that can be used as macroinitiator for grafting via atom transfer radical polymerization (ATRP) . The grafting of copolymers via ATRP have been previously studied .…”

“…The grafting of copolymers via ATRP have been previously studied . In recent years, ATRP has been employed to prepare a variety of polymers for diverse applications as its one of the most powerful reversible‐deactivation radical polymerization (RDRP) techniques, mostly due to its simplicity, polydispersity and molecular weight controllability, and monomer, initiator, catalyst, ligand, and solvent versatility, among others . In this study, PVPA was selected as the phosphonated polymer to be grafted to chloromethylated SIBS because the material contains PO 3 H 2 groups directly attached to a flexible main chain, providing chain mobility to the grafts.…”