Adsorption of Nanocolloidal SiO₂ Particles on PEO Brushes

Abstract

Introduction. The interactions between polymers at interfaces and the environment is of the utmost importance for numerous processes in biomedical applications, but also in the food industry and in paint applications. 1,2 The past two decades polymers end-grafted to interfaces at high densities, so-called polymer brushes, have been recognized as interesting objects from an academic point of view. [2][3][4][5][6] Recently, numerous studies have examined brushes as promising candidates to modify the adsorption properties of surfaces in contact with heterogeneous solutions. [7][8][9][10] For instance, the adsorption of proteins and bacteria on surfaces, also known as biofouling, may be suppressed via grafting of hydrophilic polymers. 11 However, advancement in the field of brushes in contact with heterogeneous media seems to be slow due to two reasons: (a) the difficulty of experimentally preparing well-characterized polymer brushes and (b) the current lack of model systems to study brush-particle interactions. In recent papers we reported a novel method of preparing polymer brushes on solid substrates, based on the Langmuir-Blodgett (LB) technique. [12][13][14] Also, in the past the interaction between silica surfaces and PEO-homopolymers has been examined in detail. 15 Using reflectometry to measure the adsorption of nanocolloidal SiO 2 particles onto brushes prepared via the LB-technique, we believe to have the first brushparticle system in which the polymer-polymer, polymerparticle, and particle-particle interactions can be varied independently via the pH, grafting density, and ionic strength, respectively. In this communication, we report the first results for this model system and compare the results with predictions of theoretical models.Materials and Methods. Diblock copolymers consisting of PS(38)-PEO(700) were received from Dr. G. Riess, Mulhouse, France (the numbers denote the number of monomers in the blocks). 16 The PS-PEO was dissolved in chloroform (1 g L -1 ) and deposited on the air/water interface of a Langmuir trough via a micropipet. The PS-PEO monolayer was compressed to the desired density, characterized by the surface pressure. 17,18 Silicon wafers were hydrophobised using styrene as described in refs 19 and 20. On top of the styrene monolayer a PS layer of thickness 60 to 70 nm was spincoated at 3000 min -1 from a 14 g L -1 solution in toluene. Subsequently, the PS-PEO monolayer was transferred onto the coated wafer via the well-known LB-technique. 21 The interaction between the PS-groups on the block copolymer and the spin-coated PS layer is strong enough to provide stable PEO-brushes, irrespective of the solution conditions.

Formation of surface-grafted polymeric amphiphilic coatings comprising ethylene glycol and fluorinated groups and their response to protein adsorption

“…Previous theoretical and experimental studies on polymer/nanoparticle hybrids prepared by diffusing nanoparticles inside swollen homopolymer brushes have provided clear evidence that the penetration depth of the particles depends on the interplay between the size of the particle and the grafting density and molecular weight of the brush. [35][36][37][38][39][40][41] Similar effects are expected to control the distribution of the fluorinating moieties in the P͑HEMA-cofHEMA͒ RCP brushes. In order to address the interplay between the size and reactivity of the modifying agent, we employed a variety of commercially available fluorinated compounds.…”

Interaction between Polymer Brush and Nanoparticle: Brownian Dynamics Investigation

“…Let us note that the diusion coecient is of the order of 10 −3 , which implies that the dimensionful coecient is of the order of 10 −6 cm 2 /s [34]. In experiment related to the adsorption of nanocolloidal SiO 2 particles onto brushes, there is a maximum in the adsorbed amount as a function of the grafting density [19]. To a certain extent, from the degree of one nanoparticle penetration in polymer brush, one can qualitatively analyze the absorbed amount of many nanoparticles on brush in experiments.…”

“…[19]. In fact, we simply use the sum of all the monomers above the nanoparticle to analyze the overall adsorbed amount of nanoparticles.…”

“…Experiments show that with the increase of the grafting density of brush, the amount of the adsorption nanoparticles on brush has a maximal value [19]. High grafting density means more adsorption monomers, correspondingly, the steric repulsions between monomers are strong and the nanoparticle cannot penetrate deep.…”

The Distribution of Immobilized Platinum and Palladium Nanoparticles within Poly(2‐vinylpyridine) Brushes

“…This includes dendrimers, [ 4,5 ] microgels, [6][7][8] latex particles, [ 9,10 ] and polymer brushes. [11][12][13][14][15][16][17] Among these different approaches, polymer brushes are attracting a considerable amount of attention because of the advantages they can offer. They are easily addressed, and can be used to immobilize and stabilize the NPs simultaneously with no additional stabilizers.…”