Fabrication techniques polymer brushes

An early attempt on stimulus-responsive polymer-incorporated nanochannels was conducted by Yameen et al. The authors started with PI microfilms at the thickness of 12 pm/ The conical nanochannels were fabricated through the ion-etching technique as mentioned above. In the nanochannels, the PNIPAAm polymer brushes were produced via surface-initiated atom transfer radical polymerization. As PNIPAAm responds to thermal stimuli in the form of extension and retraction, the functionalized nanochannels can be opened/closed according to the environment temperature. 

In the past few years there has been a real surge of new techniques for the preparation of porous materials that are characterized by well-defined cylindrical pores of sizes from a few micrometers, down to the nanometer range. Most notably, porous anodic alumina (PAA) [17] and porous silicon (p-Si) [18,19] that are prepared by electrochemical anodization, and track-etched polymer membranes (polycarbonate, polyimide, polyethylene terephtalate, etc.), represent the most well-known cases of porous membranes that are candidates for filtration applications and also for their use as templates in nanotechnology (nanowire fabrication [20]). The pore diameter range of these membranes is comparable to the typical thickness of polymer brushes that are usually prepared in the laboratory. 

There have been various experimental efforts for the fabrication of concave polymer brushes inside cylindrical pores by grafting from techniques. The most notable examples include... 

It is evident that the continuing breakthroughs in nanofabrication techniques will permit in the near future the reproducible fabrication of complex pore-brush structures that will be specifically tailored for single or multiple tasks. The rich chemistry and physics of polymer brushes provide many advantages and would certainly lead to their incorporation in a plethora of applications. 

The number of techniques available to generate brush-like polymer gradients is large. The first part of this subsection will deal with the fabrication methods that employ silanes as grafting sites on the surface. The second part of the subsection covers all other techniques that allow brush-like polymer gradients to be created. 

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