Water-absorbing characteristics of acrylic acid-grafted carboxymethyl cellulose synthesized by photografting

✍ Scribed by Shin Kuwabara; Hitoshi Kubo

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 466 KB
• Volume: 60
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19960613)60:11<1965::aid-app20>3.0.co;2-z

✦ Synopsis

Cellulosic absorbents for water were synthesized by photografting (A > 300 nm) acrylic acid (AA) onto fiberous carboxymethyl cellulose (CMC, degree of substitution [DS] = 0.1-0.4) at 30°C in the presence of N,N-methylenebisacrylamide as a crosslinker. The CMC sample was pretreated with hydrogen peroxide in the presence of sulfuric acid to prepare CMC peroxides with a peracid type as a polymeric photoinitiator. The peroxides were active for the photografting and AA could be grafted onto CMC with percent graftings higher than 150% by photoirradiation of 10 min at 30°C. The amount of water absorbed increased with increasing percent grafting of AA and DS of CMC. The amount was reduced considerably when the absorbents were prepared by the photografting of AA onto crosslinked CMC in the absence of the crosslinker. Graft copolymers which display a decreasing water absorbency as a function of temperature were prepared by two methods: In the first synthesis method, AA and N-isopropylacrylamide (NIPAAm) binary monomers were graft-copolymerized onto CMC samples using photoinitiation. In the second method, photografting of AA was followed by a second-step photografting of NIPAAm to produce a terpolymer with two types of side chains of differing repeat unit composition on the CMC substrate. Graft copolymers formed by both methods showed decreasing water absorbency as temperature increased with losses in water absorbency of up to about 60% as the temperature was increased above 30°C. Effects of NIPAAm composition and crosslinker content in the graft copolymers on the decreasing water absorbency as a function of temperature were also examined. 0 1996 John Wiley & Sons, Inc.