Sirikanya Wuttigul. Smart Material with Dynamic Surface Properties Based on Carbon Dioxide Reversible Reaction. Master's Degree(Chemical Engineering). King Mongkut's University of Technology Thonburi. KMUTT Library.. : King Mongkut's University of Technology Thonburi, 2552-12-27.
Smart Material with Dynamic Surface Properties Based on Carbon Dioxide Reversible Reaction
Abstract:
Self-assembled monolayers (SAMs) were prepared on silicon wafers using
Trimethoxylpropyl (poly-ethylenimine) by dip-coating technique. Prior to be used, the
silicon substrates were treated with piranha solution and were ready for the monolayer
dip-coating. The poly(ethyleneimine) (PEl) modified surfaces were characterized by
Multi-angle ellipsometry spectroscopy, static water contact angle measurements and
X-ray Photoelectron Spectroscopy to determine surface layer thickness, hydrophilicity
changes during the modification and chemical composition on the PEl modified
surfaces, respectively. The characterization results showed that Trimethoxy
poly(ethyleneimine) silane self-assembled monolayers (SAMs) were deposited onto
silicon (Si) wafer by dip-coating technique and the layers were not uniform due to the
polymer brush of PEI. The C and N atomic percentages were lower than theoretical
values while the O atomic percentage was higher. This result was rationalized by the
fact that the silicon surface was not completely covered with the amine layer and there
was unexpected carbon present. In order to prepare the SAMs surface for initiator
functionalization, the dip-coating technique was used to coat cellulose on the treated
and PEl SAMs surface. Results showed that the cellulose surface did not show any
significant differences in the thickness of cellulose layer when increasing cellulose
concentration and reaction time for dip-coating on PEl modified surfaces. The tendency
of hydrophilicity from treated and PEl modified surfaces increased after grafting with
cellulose. For the investigation of the reversible reaction of CO2 with the functionalized
surface, the solvent played a role on the reaction on the functionalized surface but there
was no change in contact angle when CO2 was blown onto functionalized surface
without solvent coating. The demonstration of reversibility of C02 reaction showed that
C02 on the surface after C02 reaction can be partly removed by placing the sample
under vacuum at 60 C. ATRP technique was used to modify PEl SAMs and cellulose
surface. The thickness of 2-vinylpyridine was lower than DMAEMA and non-uniform,
while the thickness of DMAEMA was more uniform. The suitable concentration of
initiator was determined for each monomer and the molecular structure of monomer was
significant for optimum morphology and thickness.