Chemistry in adsorbed monolayers. 2. Thermal and photochemical grafting reactions at the polymer-filler interface

We prepared novel bipolar membranes (BPMs) consisting of cation and anion exchange layers (CEL and AEL) using radiation-induced asymmetric graft polymerization (RIAGP). In this technique, graft polymers containing cation and anion exchange groups were introduced into a base film from each side. To create a clear CEL/AEL boundary, grafting reactions were performed from each surface side using two graft monomer solutions, which are immiscible in each other. Sodium p-styrenesulfonate (SSS) and acrylic acid (AA) in water were co-grafted from one side of the base ethylene-co-tetrafluoroethylene film, and chloromethyl styrene (CMS) in xylene was simultaneously grafted from the other side, and then the CMS units were quaternized to afford a BPM. The distinct SSS + AA- and CMS-grafted layers were formed owing to the immiscibility of hydrophilic SSS + AA and hydrophobic CMS monomer solutions. This is the first BPM with a clear CEL/AEL boundary prepared by RIAGP. However, in this BPM, the CEL was considerably thinner than the AEL, which may be a problem in practical applications. Then, by using different starting times of the first SSS+AA and second CMS grafting reactions, the CEL and AEL thicknesses was found to be controlled in RIAGP.

Download Full-text

An Equivalent Circuit Approach to Evaluating Conductivity of Polymer-Filler Composites

MRS Proceedings ◽

10.1557/proc-734-b9.19 ◽

2002 ◽

Vol 734 ◽

Author(s):

Vladislav Skorokhod

Keyword(s):

Equivalent Circuit ◽

Equivalent Circuit Model ◽

Conductive Filler ◽

Size Ratio ◽

Particulate Composites ◽

Mathematical Representation ◽

Matrix Size ◽

Linear System Of Equations ◽

Polymer Filler

ABSTRACTAn equivalent circuit model of electrical conduction in polymer-filler particulate composites was developed in this study. The equivalent circuit was constructed for an individual composite particle with a sub-monolayer of conductive filler, where the filler particles play the role of circuit nodes, and inter-particle contacts are represented by resistors between the nodes. The mathematical representation of the equivalent circuit in the form of a linear system of equations for nodal potentials was solved numerically with Matlab software to calculate conductance of the composite as a function of the amount of conductive filler, filled fraction of the monolayer, filler-to-matrix size ratio and the degree of structuredness (non-randomness) of the filler material. Additionally, percolation concentrations and statistical distributions of composite conductance were calculated as functions of the filler-to-matrix size ratio.

Download Full-text

Flash grafting of functional random copolymers for surface neutralization

Journal of Materials Chemistry C ◽

10.1039/c4tc00328d ◽

2014 ◽

Vol 2 (25) ◽

pp. 4909-4917 ◽

Cited By ~ 32

Author(s):

F. Ferrarese Lupi ◽

T. J. Giammaria ◽

G. Seguini ◽

M. Ceresoli ◽

M. Perego ◽

...

Keyword(s):

Thermal Processing ◽

Silicon Surface ◽

Rapid Thermal Processing ◽

Random Copolymer ◽

Random Copolymers ◽

Grafting Reactions

Rapid Thermal Processing (RTP) technology was employed to perform flash grafting reactions of a hydroxyl terminated poly(styrene-r-methylmethacrylate) random copolymer to a silicon surface.

Download Full-text