Diblock copolymer, polyethylene oxide/polystyrene

ATRP has been used to prepare AB diblock, ABA triblock, and most recently ABC triblock copolymers (17). To date, the techniqne has been used to create block copolymers based on polystyrene and varions polyacrylates (16). However, it is possible to synthesize a so-called macroinitiator by other polymerization mechanisms (anionic, cationic, etc), and nse this in the ATRP of vinyl monomers. Examples, such as the anionic polymerization of PEG macroinitiators for ATRP synthesis of polyethylene oxide/polystyrene block copol5uners, are discussed in Reference 16. 

Several other di- and triblock copolymers have been synthesized diblocks of polystyrene-block-polyvinyl alcohol triblocks of polymethyl methacrylate-block polyethylene oxide-polymethyl methacrylate diblocks of polystyrene-polyethylene oxide and triblocks of polyethylene oxide-polystyrene-polyethylene oxide. 

Sullan et al. further applied AFM-based force mapping to quantify, by means of breakthrough forces, the nanomechanical stability of raft-forming DOPC/ESM/Chol lipid bilayers in the presence of diblock copolymers comprised of polystyrene (PS) and polyethylene oxide (PEO). Varying molecular weights of PS-b-PEO (PS(3.6)-b-PEO(25), PS(3.6)-b-PEO(16.6), PS... 

Self-assembled block copolymers are basically amphilic molecules which contain distinctively different polymers. This block copolymer contains two or more polymers quantitatively in the form of blocks. Some of the block copolymers are polyacrylic acid, polymethylacrylate, polystyrene polyethylene oxide, polybutadiene, polybutylene oxide, poly-2-methyloxazoline, polydimethyl sUoxane, poly-e-caprolactone, polypropylene sulfide, poly-A -isopropylacrylamide, poly-2-vinylpyridine, poly-2-diethylamino ethyl methacrylate, poly-2-(diisopropylamino) ethyl methacrylate, poly-2-(methacryloyloxy) ethyl phosphorylcholine, and polylactic acid. These copolymers contain more than polymers to form certain configurations like linear, branched, patterned. For example, if we take three polymers named A, B, and C, they can be combined to form arrangements AB, BA, AA, BAB, ABCAB, ABCABC, ABABAB, etc. in the form of branched configuration it forms (ABQa, (ABA)a, (AB)4, etc. Depending on the above-mentioned number of blocks, they are named as AB diblock copolymers, ABC triblock copolymers, ABC star block copolymers, etc. The covalent linkage between these different blocks of polymers makes macroscopic phase separation impossible, that is, in its place the phase separation... 

The above triblocks are not the most efficient emulsifiers or dispersants—the PPO chain is not sufficiently hydrophobic to provide a strong anchor to a hydrophobic surface or to an oil droplet. The surface activity of the PEO-PPO-PEO triblock at the OAV interface is probably due to rejection anchoring the PPO chain is not soluble in water or most oils. Several other di- and triblock copolymers have been synthesized diblocks of polystyrene block-polyvinyl alcohol triblocks of poly(methylmethacrylate)-block polyethylene oxide-poly(methyl methacrylate) diblocks of polystyrene-polyethylene oxide triblocks of polyethelene oxide-polystyrene-polyethylene oxide. 

Problem 12.7 A combination of core rst and coupling onto approaches often offers a simple strategy to synthesize star block copolymers. Suggest, accordingly, a synthetic strategy for the preparation of 3-arm star block copolymers consisting of diblock polymeric arms, polystyrene- polyethylene oxide (PSt-fc-PEO). 

In this section we will describe the results of our angular dependent XPS measurements, XPS (0), which were made on a series of polystyrene (PS)-polyethylene oxide (PEO) diblock (PS-PEO) and triblock (PEO-PS-PEO) copolymers. Table 3 contains the copolymer composition and molecular weight data for the various block copolymers employed in this study. The synthesis, purification and characterization of these materials has been described previously. (H)... 

XPS spectra of polystyrene (top), polyethylene oxide (middle) and a polystyrene-polyethylene oxide diblock copolymer (bottom). 

---