ISSN:
0887-624X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Cellulose-MMA graft copolymers have been produced using aqueous-based, Ce(IV)-initiated and periodate-initiated systems and also photochemical initiation. The reaction variables studied include the effect on grafting of varying the MMA monomer concentration, the initiator type and concentration, and also the reaction time. Of the three initiator types examined, the Ce (IV)-initiated and the photochemically-initiated systems are comparable in their effects on graft copolymer formation. Concurrent homopolymer formation was in the region of 50% by weight. Periodate-initiation leads to less efficient grafting of MMA onto cellulose, although homopolymer formation is also lower (typically 〈20% by weight). The characterization of the copolymeric products through their properties as solids and, as their carbanilated derivatives, through their solution properties has been undertaken. Values of the activation onergy of decomposition (EA) of the cellulose-MMA graft copolymers decrease with increasing MMA content, ranging between 227 and 155kJ mol-1. There is also a dependence on initiator type and grafting reaction conditions used (EA (cellulose wood pulp) = 239 kJ mol-1; EA (PMMA) = 115 kJ mol-1). Quantitative zeta-potential (ζ) determinations for cellulose-MMA graft copolymer samples produce negative surface charge density (σ) values. At a comparable MMA grafting level of 70-80%, values are of the order: photochemical (-730 esu/cm2) 〉 periodate (-470 esu/cm2) 〉 Ce (IV)-initiation (-351 esu/cm2). Characterization of carbanilate solutions (by rheological examination) and of dry, carbanilate films (by study of surface wetting behavior) highlighted differences in the physical conformation of copolymers prepared by the different initiation routes. The highly degradative effect on cellulose of a periodate initiator, in comparison with the Ce (IV)-initiation system, is reflected in significantly reduced molar mass values (typically, Mn 65,000 as opposed to 130,000 for Ce (IV)-initiated graft copolymer carbanilates).
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pola.1991.080290909
Permalink
