Adsorption Behavior of Polystyrene−Polyisoprene Diblock Copolymers with Zwitterionic Groups Using Quartz Crystal Microbalance:  Effect of Different Microstructures

Abstract

The adsorption behavior of poly(styrene-b-isoprene) (PS-b-PI) copolymers functionalized with polar sulfobetaine zwitterionic groups at different positions along the backbone was investigated. Using dilute solutions in toluene, adsorption onto gold surface was investigated using a quartz crystal microbalance (QCM). ZwIS and ZwSI, ZwISZw, and SZwI are PS-b-PI copolymers functionalized at the α-position (zwitterionic group is attached to isoprene or styrene), at the α , ω-positions, and at the junction-point in the chain, respectively. The copolymers showed interesting adsorption behavior according to the zwitterion position. The adsorption isotherms for the copolymers exhibited typical Langmuir isotherm behavior. They showed different adsorbing amounts, which was explained by possible conformational states of copolymers on the surface. It was found that the position of zwitterionic groups has a major role on adsorption kinetics despite similar molecular weight and composition for the copolymers.

Looped Polymer Brushes Formed by Self-Assembly of Poly(2-vinylpyridine)−Polystyrene−Poly(2-vinylpyridine) Triblock Copolymers at the Solid−Fluid Interface. Kinetics of Preferential Adsorption

“…Many authors have used eq 4 to describe the fast initial regime and calculate diffusion coefficients. 11,16,23 However, eq 4 is based on the following assumptions: 9 (a) there are no interactions between an incoming chain and previously attached chains, and (b) every chain that approaches the surface instantaneously attaches to it. These two conditions are unlikely to be true in a real system; the incoming polymer must have a conformation whereby the anchoring end units access the surface.…”

Polymer Loops vs. Brushes on Surfaces: Adsorption, Kinetics, and Viscoelastic Behavior of α,ω‐Thiol Telechelics on Gold

“…An initial linear increase in the adsorbed amount with the square root of time traditionally indicates a transport-limited regime where diffusion of the polymers to the surface is the rate-limiting step, leading to a surface coverage with little interaction between individual polymer chains. The slope of the A vs. t 1/2 in this linear regime provides a measure of the diffusion coefficient as described by the expression: [48][49][50] AðtÞ ¼ 2c 0 p 1=2 ðDtÞ 1=2 (3) where D is the diffusion coefficient of the polymer in solution and c 0 is the initial bulk concentration. It should be noted that this model does not apply to the initial moments (%10 s which were neglected) of the adsorption process since we do not have a uniform concentration and c 0 is changing rapidly during the injection of the polymer solution.…”

“…Other groups have applied Equation (3) to calculate the diffusion coefficient of end-functionalized polymers and block copolymers and have reported good agreement with values obtained from dynamic light scattering (DLS). [49,51,52] In most cases, these systems possess a thermodynamic driving force for adsorption to occur (i.e., poor solvation of one block component, ionic end-groups, etc.). Interestingly, we obtained diffusion coefficients on the order of 10 À10 -10 À12 cm 2 Á s À1 , which is several orders of magnitude lower than the expected rate of diffusion (10 À7 cm 2 Á s À1 ) for these polymers under a purely diffusion-controlled process.…”

Adsorption of Block Copolymers from Selective Solvents on Curved Surfaces

“…In order to provide additional degrees of freedom that would enable the control of structural properties of the adsorbed layer, recent work utilized systems that include block copolymers having blocks with dissimilar chemical features. [26][27][28] In these systems, polymer adsorption will be governed by the specific interfacial interactions of each block with each other, with the surface, and with the solvent.…”