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PIGMENT DISPERSANT DIBLOCK COPOLYMERS VIA STABLE FREE RADICAL POLYMERIZATION

IP.com Disclosure Number: IPCOM000027423D
Original Publication Date: 1996-Oct-31
Included in the Prior Art Database: 2004-Apr-07
Document File: 4 page(s) / 144K

Publishing Venue

Xerox Disclosure Journal

Abstract

Polystyrene-block-poly(acrylic acid) block copolymers were synthesized successfully by Stable Free Radical Polymerization (SFRP) and evaluated for electrical performance, HOGaPc pigment dispersion stability, and BGL film quality.

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XEROX DISCLOSURE JOURNAL

PIGMENT DISPERSANT DIBLOCK COPOLYMERS VIA STABLE FREE RADICAL POLYMERIZATION Nancy A. Listigovers Cheng-Kuo Hsiao
Marko D. Saban
Michael K. Georges
Gordon K. Hamer

Proposed Classification
U. S. C1.430/110 Int. C1. G03g 091097

Polystyrene-block-poly(acrylic acid) block copolymers were synthesized successfully by Stable Free Radical Polymerization (SFRP) and evaluated for electrical performance, HOGaPc pigment dispersion stability, and BGL film quality.

Synthesis and Characterization of Polystyrene-block-Poly(Acry1ic Acid)

Synthesis by anionic polymerization required that the carboxylic acid be protected and therefore, t-butylacrylate was used as a masked form of acrylic acid. The polystyrene-b- poly(t-butylacrylate) copolymer was then hydrolyzed, using a catalytical amount of p-toluenesulfonic acid, to give the desired poly(acrylic acid) block. The same synthetic sequence was followed for SFRP synthesis for solubility reasons. In the future, it may be possible to synthesize the poly(acry1ic acid) block directly from acrylic acid monomer.

TEMPO-tenninated polystyrene (Mw=29K), was used as te precursor to the block copolymer. It was dissolved in a mixture of t-butyl acrylate monomer and DMSO, then heated in an oil bath at 140°C. At this temperature, the TEMPO-styryl bond is labile generating the styryl free racial which is capable of further polymerization with available monomer. The progress of the polymerization is monitored using gel permeation chromatography and polymerization can be stopped at any time by simply removing the heat source. In this way, block copolymers containing varying amounts of poly(t-butyl acrylate) were prepared and then hydrolyzed to give the corresponding poly(acrylic acid) containing material. For example, four block copolymers containing a polystyrene block of Mw=29K and a poly(t-butyl acrylate) block representing 10, 12, 16 and 19mol%, respectively, have been prepared.

XEROX DISCLOSURE JOURNAL - Vol. 21, No. 5 SepternbedOctober 1996 345

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PIGMENT DISPERSANT DIBLOCK COPOLYMERS VIA STABLE FREE RADICAL POLYMERIZATION (CONT'D)

Evaluation of a PS-b-PAA Copolymer as a Dispersanminder Polymer for HOGaPc

The block copolymer was used as a direct replacement for the commercially available binder polymers (e-g. PVB) typically used in the P/R BGL. The BGL coating dispersion was prepared by combining 0.2623 grams of PS-b-PAA copolymer, 0.50 grams of HOGaPc, 70 grams of glass beads and 22.9 ml of solvent, in a 60 ml bottle and shaking for 2 h...