Graft polymers morphological structure

For ETFE- -PSSA membranes with the same lEC, water uptake is higher than MeOH uptake of the membrane, but for Nation and S-SEBS membranes, MeOH uptake of membrane is always higher than water uptake. Chemical structure and morphology of membranes affect the solvent absorption. Nafion is considered to consist of ionic clusters that are separated from the polymer phase. For grafted polymers, heterogeneity exists to some extent due to the hydrophobic base polymer however, a regular clustered structure, as in the case of Nafion, has not been proposed for these materials. 

The same aplies to polymer brushes. The use of SAMs as initiator systems for surface-initiated polymerization results in defined polymer brushes of known composition and morphology. The different polymerization techniques, from free radical to living ionic polymerizations and especially the recently developed controlled radical polymerization allows reproducible synthesis of strictly linear, hy-perbranched, dentritic or cross-linked polymer layer structures on solids. The added flexibility and functionality results in robust grafted supports with higher capacity and improved accessibility of surface functions. The collective and fast response of such layers could be used for the design of polymer-bonded catalytic systems with controllable activity. 

Figure 15. Morphological structure of controlled graft polymers.

The effect of polymer morphology on membrane structure and conductance has been shown recently. In Ref. 25 hydrogen-based graft-copolymer membranes were compared in terms of morphology and performance to random copolymer membranes with the same ion content. For the hydrated grafted membranes TEM micrographs revealed a picture of a continuous phase-separated network of water-filled channels with diameters of 5 nm. In contrast to that, the random copolymer membranes exhibit a reduced tendency toward microphase separation water is... 

We have prepared pH/temperature-sensitive polymer membranes by grafting AAc or NIPAAm or AAc and NIPAAm on the surface of polyamide and polysulfone membranes, utilizing plasma and UV radiation teehniques. The structure of the graft chain was confirmed by XPS and ATR-FTIR spectra. Through this study, we investigated the morphology and permeability of the riboflavin of the unmodified and modified polymer membranes. AAe or NIPAAm or AAc and NIPAAm-grafted polymer membranes showed the pH or temperature and pH-dependent permeation behaviours of riboflavin, respectively. 

In this chapter, a series of recent results in surface modification of various surfaces employing the macromolecular anchoring layer approach was overviewed. It was demonstrated that the approach could be used as a virtually universal method for grafting of functional polymer brushes. The properties of the bmshes can be controlled by polymer nature, structural and morphological factors, and external stimuli. The polymer grafting technique developed can be readily applied to surface modification of fibers and textiles, leading to generation of hydrophobic, hydrophilic and switchable fibrous materials. 

Post-polymerization modification of reactive polymer films provides the possibility to design complex coatings associated with intricate structure and morphology [1, 4, 97, 98]. Using a simple procedure, two or more types of chemical functionalities can be applied onto substrates that are contained in covalently grafted polymer films. Multifunctional surfaces can be fabricated by sequential click reactions or simultaneous multiple click reactions in one-pot. Click-like reactions such as thiol-based additions, activated ester coupling, and azide-alkyne cycloadditions are those most used for post-polymerization modification, because these reactions yield orthogonal reactive polymer brushes rapidly and quantitatively [17]. 

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