Hydrophobic-polar copolymers

For MMA-MAA copolymerizations carried out in the more hydrophobic solvents (toluene, dioxane), MAA is the more reactive towards both propagating species while in water MMA is the more reactive. In solvents of intermediate polarity (alcohols, dipolar aprotic solvents), there is a tendency towards alternation. For these systems, choice of solvent could offer a means of controlling copolymer structure. 

Abstract Protein-like copolymers were first predicted by computer-aided biomimetic design. These copolymers consist of comonomer units of differing hydrophilicity/hydro-phobicity. Heterogeneous blockiness, inherent in such copolymers, promotes chain folding with the formation of specific spatial packing a dense core consisting of hydrophobic units and a polar shell formed by hydrophilic units. This review discusses the approaches, those that have already been described and potential approaches to the chemical synthesis of protein-like copolymers. These approaches are based on the use of macromolecular precursors as well as the appropriate monomers. In addition, some specific physicochemical properties of protein like copolymers, especially their solution behaviour in aqueous media, are considered. 

All the described properties of such a s-fraction of poly(NVCl-co-NVIAz) synthesized at the temperature above the PST of the reacting system allowed us to draw the conclusion that the chains of this type had the comonomer sequence, which at the temperatures above the conformation transition facilitated the formation of polymer particles, where H-blocks are in the interior shielded by the P-blocks against additional intermolecular association. Such a behaviour of this copolymer in aqueous media is close to that of oligomeric proteins similar to casein [46] possessing a rather hydrophobic core surrounded by the polar segments. 

The designed set of 2-oxazoline monomers that was used for the synthesis of the triblock copolymers (MeOx, EtOx, PheOx, and NonOx) yielded polymers of different polarity [91], P(MeOx) and P(EtOx) are hydrophilic, whereas P(PheOx) and P(NonOx) are hydrophobic. All possible combinations of these four different monomers would result in 64 different structures. However, all polymers that would have two times the same block after each other were excluded since they do represent diblock copolymers. Additionally, some structures, which have NonOx as the first block and EtOx or MeOx as the second block, were excluded due to extensive side reactions. Consequently, 30 different triblock copolymers were synthesized, and they are listed in Table 13 with their corresponding structural characterization. 

Hydrophobic sorbents including octadecyl, octyl, diphenyl, cyclohexyl, phenyl, butyl, ethyl, methyl, and copolymers of styrene and divinylbenzene can be applied for retaining nonpolar to medium polar analytes. In this list, the styr-ene-divinylbenzene copolymer phases such as PRP-1 and XAD-2 are the most nonpolar phases, while the methyl phase is the least nonpolar one. The analytes are adsorbed onto the hydrophobic materials by means of van der Waals interactions and, to some extent, by hydrophobic bonding or dipole-dipole interactions. 

Dan, N. and M. Tirrell. 1993. Self-assembly of block copolymers with strongly charged and a hydrophobic block in a selective, polar solvent. Micelles and adsorbed la ifasromolecule 6 4310—4315. 

Fig. 2 Schematic representation of a the HP model and b the dumbbell HA model of an amphiphilic copolymer. P-units are hydrophilic (polar), H-units are hydrophobic, and A-units are amphiphilic. (Adapted from Ref. [25])...

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