Adsorption-tuned copolymers

The idea of conformation-dependent sequence design via polymer-analogous transformation can be generalized in many respects [23]. Indeed, a special chemical sequence can be obtained not only from a globular conformation any specific polymer chain conformation can play the role of parent. 

The simplest example of this kind is connected to the conformation of a homopolymer partly adsorbed onto a flat substrate (Fig. 9). Let us assume that the chain segments being in direct contact with the surface in some typical instant conformation (Fig. 9a) are chemically modified (Fig. 9b). This can take place when the surface catalyzes some chemical transformation of the adsorbed segments. One can expect that after desorption (Fig. 9c), such a copolymer will have special functional properties it will be tuned to adsorption . 

Following this line, Zheligovskaya et al. [55] compared the adsorption properties of copolymers with special adsorption-tuned primary structures (adsorption-tuned copolymers, ATCs) with those of truly random copoly- 

It should be noted that the development of such polymer systems is stimulated by existing experimental works. In particular, the experimental methods of preparation of nanometer-sized hollow-sphere structures have been suggested [58-63] because of their possible usage for encapsulation of molecules or colloidal particles. The preparation of hollow-sphere structures, generally, is based on self-assembling properties of block copolymers in a selective solvent, i.e., on the formation of polymer micelles with a nanometersized diameter. Further cross-finking of the shell of the micelle and photodegradation [64] of the core part produce nanometer-sized hollow cross-linked micelles. 

The sequence design procedure proposed in [57] can be described in more detail as follows. 

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Fig. 9 Schematic representation of the sequence design procedure leading to an adsorption-tuned copolymer a initial partly adsorbed homopolymer, b chemical modification of adsorbed chain segments, c resulting copolymer. Modified segments are shown in gray...

The focus here will be on the consideration of designed copolymers exhibiting selective interactions with the surfaces and interfaces. In particular, we will consider some properties of adsorption-tuned copolymers and partly cross-Unked polymer envelopes that function as a molecular dispenser. 

Zheligovskaya et al. [55] have simulated the adsorption of quasirandom adsorption-tuned copolymers (ATC). The critical adsorption energy as well as some characteristics of the adsorbed single chains (statistics of trains, loops, and tails) were studied. All these properties were compared with those... 

Following this line, Zhdigovskaya et al ° compared the adsorption properties of copolymers with special adsorption-tuned primary stmctures (adsorption-tuned copolymers, ATCs) with those of truly RCPs and random-block copolymers. Monte Carlo simulations revealed that specific features of the ATC primary stmaure promoted the adsorption of ATC chains, in comparison with thdr random and random-block counterparts under the same conditions. In other words, the resultant copolymer sequence memorized the original state of the adsorbed homopolymer chain. Its statistical properties exhibit LRCs of the LF type similar to those found for PLCs obtained via PAT of a homopolymer globule. ... 

Figure 8 Top panel Schematic representation of the sequence design procedure leading to an adsorption-tuned copolymer, (a) Initial partly adsorbed homopolymer, (b) chemical modification of adsorbed chain segments, (c) resultant copolymer. Modified segments are shown in red. Bottom panel Stages of preparation of copolymer envelope, (a) Adsorption of homopolymer chain on a colloidal particle, (b) coloring of the polymer chain (blue color corresponds to chemically modified monomer units and red color to adsorbed units) and introduction of cross-links (shown as green sticks) to stabilize hollow-spherical structure, and (c) elimination of the core particle.

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