Thermoresponsive PDMAEMA Brushes: Effect of Gold Nanoparticle Deposition

Abstract

The paper addresses the effect of gold nanoparticle (Au-NP) deposition on the thermoresponsive volume phase transition of the weak polyelectrolyte poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes. PDMAEMA brushes were synthesized via surface-initiated atom transfer radical polymerization (SI-ATRP). The PDMAEMA/Au-NP composite brushes were fabricated by immersing the brush modified wafer in the Au-NP suspension. Atomic force microscopy (AFM), ellipsometry, and scanning electron microscopy (SEM) have been employed to characterize the neat PDMAEMA brushes and PDMAEMA/Au-NP composite brushes. All neat PDMAEMA brushes swelled below the volume phase transition temperature and collapsed with increasing temperature over a broad temperature range independent of the initial brush thickness. Water uptake of the brushes is also independent of initial brush thickness. The adsorption of the charged Au-NPs significantly affects the degree of swelling and the thermoresponsive properties of the brushes. PDMAEMA/Au-NP composite brushes do not exhibit any noticeable phase transition at the experimental temperature range irrespective of the initial brush thickness. The reason for this behavior is attributed to a combination of the following: the decreased conformational entropy of the Au-NP adsorbed polymer chains, the increased hydrophilicity of the system due to the charged Au-NPs, and the ≈13 nm diameter Au-NPs causing steric hindrance. We have also shown that the AFM full-indentation method can be successfully applied to determine the polymer brush thicknesses.

Thin Poly(Di(Ethylene Glycol)Methyl Ether Methacrylate) Homopolymer Brushes Allow Controlled Adsorption and Desorption of PaTu 8988t Cells

“…[22][23][24] The pioneering work of Okano and co-workers in this area, who exploited PNIPAM brushes as a workhorse system, has been more recently expanded to included brushes of PNIPAM-co-poly-(oligoethylene glycol) methacrylate (POEGMA), POEGMAco-PDEGMA, poly(MEO 2 MA 50 -co-HOEGMA 20 -co-HEMA 30 ), poly(dimethylaminoethyl methacrylate), and poly[tri-(ethylene glycol) ethyl ether methacrylate]. [1,[25][26][27][28] Homopolymer brushes that exhibit a lower critical solution temperature (LCST) in the vicinity of physiological temperatures are scarcer. Poly(di(ethylene glycol)methyl ether methacrylate) (PDEGMA) possesses a bulk LCST of 26 °C, which is increased in brushes to 32 °C, is known to afford cell and protein resistant coatings.…”

Effect of Architecture of Thermoresponsive Copolymer Brushes on Switching of Their Adsorption Properties

“…[17,18] The responsiveness of these brushes was utilized to design surfaces with tunable wetting properties with regard to adhesion, adsorption, friction, and other properties. [19][20][21][22][23][24][25][26][27][28][29][30][31] In one approach for the design of stimuli-responsive brushes, the switching is provided by changing the properties (charge and hydrophobicity) of the polymer themselves. [32,33] This example includes the switching of the adhesion of cells on thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) brushes.…”

“…They are also able to demonstrate switchable properties due to the stimuli‐responsive behavior of the polymer chains that were grafted onto the surface . The responsiveness of these brushes was utilized to design surfaces with tunable wetting properties with regard to adhesion, adsorption, friction, and other properties . In one approach for the design of stimuli‐responsive brushes, the switching is provided by changing the properties (charge and hydrophobicity) of the polymer themselves .…”

β-Cyclodextrin-g-Poly (2-(dimethylamino) ethyl methacrylate) as the Stabilizer and Reductant to Prepare Colloid Silver Nanoparticles in situ

“…Recently, some reports have demonstrated that PDMAEMA can act as both reducing agent and stabilizer simultaneously in the formation of gold nanoparticles, [21][22][23][24] based on the fact that Poly (2-(dimethylamino) ethyl methacrylate) (PDMAEMA) is a hydrophilic polymer with temperature and pH sensitivities, excellent biocompatibility, and a well-studied environmentally responsive polymer. 25 Such an approach greatly simplified the preparation and purification of gold nanoparticles.…”