Heavyweight dendritic inks for positive microcontact printing

Area of Science:

• Materials Science
• Nanotechnology
• Surface Chemistry

Background:

• Poly(propylene imine) dendrimers are versatile macromolecules.
• Microcontact printing (muCP) is a key technique for patterning surfaces.
• Developing new inks is crucial for advancing muCP resolution.

Purpose of the Study:

• To synthesize and characterize poly(propylene imine) dendrimers with dialkyl sulfide end groups for use as inks.
• To evaluate the performance of these dendritic inks in positive microcontact printing ((+)muCP) on gold.
• To assess the reproducibility and resolution achievable with the new dendritic inks.

Main Methods:

• Synthesis of second- and third-generation PPI dendrimers functionalized with short, medium, and long dialkyl sulfide end groups.
• Preparation of dendritic inks and their application in (+)muCP on gold substrates using poly(dimethylsiloxane) stamps.
• Selective etching of gold using an acidic Fe(NO3)3/thiourea solution to reveal the printed pattern.
• Characterization of etched samples using optical microscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM).

Main Results:

• Dendritic inks form stable monolayers on gold, exhibiting minimal lateral spreading.
• The spreading rates of dendritic inks are significantly lower compared to conventional thiols.
• (+)muCP with third-generation dendrimers achieved faithful replication of 100 nm lines.
• High feature reproducibility was observed due to multivalent sulfide attachment and high molecular mass of dendrimers.

Conclusions:

• Poly(propylene imine) dendrimers with dialkyl sulfide end groups are effective inks for high-resolution (+)muCP.
• The unique properties of these dendritic inks enable precise patterning with improved reproducibility.
• This work advances the capabilities of microfabrication techniques for nanoscale applications.