Effect of Solvent Quality and Chain Confinement on the Kinetics of Polystyrene Bromination

Abstract

We report on the kinetics of the bromination of free polystyrene (PS) chains in bulk solution and those anchored on flat solid substrates by performing the bromination reaction in different solvents, including nitrobenzene (NB), 1-chlorodecane (CD), 1-chloroundecane (CUD), and 1-chlorododecane (CDD), at various temperatures. We find that bulk bromination of PS follows the second-order kinetic in bromine and the reaction rate increases with increasing dielectric constant of the solvent (ε). In spite of ε CDD > ε CD , the bulk bromination kinetics of PS in CDD is slower than that in CD because of lower solubility of PS in CDD than in CD. In addition, we demonstrate that the reaction rates for brominating PS brushes anchored to flat solid substrates are much slower than those for brominating free PS chains in bulk solution. We attribute this behavior to steric hindrance due to PS confinement on the substrate.

A multiscale coarse-grained model to predict the molecular architecture and drug transport properties of modified chitosan hydrogels

“…[65][66][67] Different modification patterns can be achieved by performing the chemical modification on the polymer chains dissolved in solvents of different ''quality'' and correlated to the Kerr constant of the resulting modified polymer in solution. [68][69][70][71][72][73] In silico modeling provides full control over the distribution of modification groups, and represents an ideal modality for exploring the effect of modification pattern on the molecular architecture of hydrogels.…”

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

“…Such postpolymerization reaction routes commonly lead to the formation of random copolymers ͑RCPs͒, as reported earlier by several groups. 24,33,34 The amount of modifying agent that produces fHEMA units as well as the distribution of the two comonomers, HEMA and fHEMA, will depend on several system parameters, including ͑1͒ grafting density ͑ PHEMA ͒ and ͑2͒ molecular weight ͑M PHEMA ͒ of the parent PHEMA homopolymer brush, ͑3͒ the size of the fluorinating agent, and ͑4͒ the reactivity between the function group on the parent homopolymer brush ͑-OH in the ase of PHEMA͒ and the head group present in the modifying agent. 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.…”

C−H Functionalization of Commodity Polymers

“…Theradical functionalization of polyaromatic compounds is an attractive approach to install otherwise difficult to access functional groups.Early reports focused on the halogenation of polystyrene using elemental chlorine and bromine (Figure 4A). [45][46][47] Although these methods resulted in halogenated polymers,t he nonselective reactivity of halogen-centered radicals caused significant degradation of the polymers and al oss of beneficial physical properties.M ore selective approaches employing N-halosuccinimide reagents have been developed, but even highly optimized methods result in cleavage of the polymer chains. [48] Despite these challenges, the halogenation of aromatic polymers continues to be used as as urface treatment to improve the flame-retardant properties of av ariety of materials.…”