Polymer post-modification

Valkama S, Nykanen A, Kosonen H, Ramani R, Tuomisto F, Engelhardt P, Brinke G, Ikkala O, Ruokolainen J (2007) Hierarchical porosity in self-assembled polymers post-modification of block copolymer-phenoUc resin complexes by pyrolysis allows the control of micro-and mesoporosity. Adv Fund Mater 17 183-190... 

Y. Feng, L. Billon, B. Grassl, A. Khoukh and J. Francois, Hydrophobically associating polyacrylamides and their partially hydrolyzed derivatives prepared by post-modification. 1. Synthesis and characterization, Polymer, 2002, 43, 2055-2064. 

The post-modification reactions of acrylamide polymers were run as follows.6 A solution of poly(acrylamide[75mol%]-acrylic acid) (150 g, 27.5% in water) and sodium formaldehyde bisulfite (15.5 g), pH 4.3, was heated to 150° C and maintained at that temperature for four hours in a 300 ml Parr reactor which was equipped with a mechanical stirrer and a thermocouple. The pH of the resulting polymer solution at room temperature was 5.9. 

In another part of this study we wished to see the effects of post-modification treatments on the properties of the modified LDPE surface. Polyethylene samples were photosulfonated for different periods of time. Afterwards they were subjected to an after-treatment by conditioning in an electrolyte solution (aqueous KC1, 10-3 M) for 48 hours and then characterized by zeta potential measurements. This conditioning process resulted in a shift of f to even less negative values (see Fig. 8). This finding may be explained by the swelling of the polymer samples (water adsorption) in water that causes a shift of the shear plane of the electrochemical double layer into the liquid phase. This effect demonstrates that storage conditions and pre-conditioning may exert a pronounced influence on the zeta potential recorded for surface-modified polymers. Phenomena of this kind have already been described in previous literature [26,27],... 

Post-modification treatments like storage conditions (air/water) and preconditioning may exert a pronounced influence on the zeta potential obtained for surface modified polymers. Sulfonated LDPE samples, which were subjected to an after-treatment by conditioning in an electrolyte solution, showed a shift of the zeta potential to even less negative values. This may be explained by the swelling of the polymer samples, which occur during storage in aqueous media. 

B) Post-Modification Reactions of Hydrocaibon Polymers Containing Corrugated Unsaturations... 

The results obtained allow us to conclude that in several cases the polymers investigated possessed a reactivity which is qualitatively and quantitatively different from that shown by the corresponding polymers containing monoenic unsaturation. Furthermore, the peculiar reactivity of each dienic group allows the selection of a functionality more suitable for the post-modification reaction which is desired. 

Huisgen 1,3-dipolar cycloaddition (click reaction) between terminal alkynes and azides is a highly efficient approach for the post modification of polymers. This technique is tolerant to a wide rage of reaction conditions and functional groups allowing fast coupling reactions under simple reaction conditions with... 

The previous example illustrates that quantification on entirely polymeric systems is difficult to achieve and often requires elaborate post-modification steps. XPS analysis, however, can provide straightforward information on the presence of hetero-atoms from the graft polymer (e.g., phosphorus, nitrogen, and sulfur) if the substrate polymer does not contain these elements. Moreover, complexation of metal cations such as Fe ", Ni ", and Cu " can also be investigated. XPS is therefore complementary to other analysis techniques, such as UV spectroscopy and ATR-IR spectroscopy. 

We can also mention the use of bio-sourced building blocks based on cellulose or dextran. Kadla et al. described value-added materials from naturally abundant polymers for system that may serve as a platform for the design and development of biosensors [197]. A hierarchically strucmred honeycomb film from dextran-ft-PS amphiphilic linear diblock copolymers has also been described by Chen et al. leading to ordered porous bio-hybrid films. [198] Honeycomb patterned surfaces functionalized with biomolecules for specific recognition of proteins or bacteria have been also achieved either by self-assembly of amphiphilic copolymers based on galactose moieties [155] or by post-modification with peptide sequences [199]. 

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