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Abstract: Cellulose acetate is a very good film-forming polymer with major applications in cigarette filters, photographic films, cosmetics and pharmaceutics formulations and membrane separation processes. Nevertheless, its rigidity and relative hydrophobic character can be limiting drawbacks for some applications. In this work, new cellulose acetate materials with highly flexible and hydrophilic grafts were obtained with different hydrophilic/hydrophobic balances. Cellulose acetate was grafted with methyl diethylene glycol methacrylate (MDEGMA) from brominated macroinitiators by atom transfer radical polymerization (ATRP) in two steps. The first step consisted of introducing ATRP initiator groups on cellulose acetate by reacting hydroxyl side groups with 2-bromoisobutyryl bromide. A preliminary study was then carried out to determine the experimental conditions for the controlled ATRP of MDEGMA homopolymerization in a solvent (cyclopentanone) compatible with cellulose acetate grafting. In these conditions, the MDEGMA homopolymerization followed Hanns Fischer’s kinetics model accounting for the radical persistent effect. The ATRP grafting was then investigated for two cellulose acetate macroinitiators differing in the number of their ATRP initiator groups. Two families of graft copolymers with nano-structured architectures were obtained. The first family corresponded to copolymers with a high number of short grafts. The copolymers of the second family had almost the same graft weight fractions but a small number of long grafts. The morphology of the graft copolymers was then investigated by synchrotron X-ray scattering. The most informative results showed that the phase segregation depended upon the number and length of the poly(MDEGMA) grafts. The copolymer with 44 wt.% of long grafts showed a segregated morphology of nano-domains with sharp interfaces and a radius of gyration of 11.5nm (from Guinier’s law). These cellulose acetate copolymers eventually led to strong films with potential applications in membrane separations. [Copyright &y& Elsevier]

Abstract: In Europe, ethyl tert-butyl ether (ETBE) is currently considered as one of the most promising bio-fuels when it is obtained from bio-ethanol. Nevertheless, its industrial synthesis process leads to an azeotropic mixture containing 20wt% of ethanol which has to be removed for fuel applications. In this work, new graft copolymers cellulose acetate-g-poly(methyl diethylene glycol methacrylate) are considered for the purification of ETBE by pervaporation. Two families of graft copolymers were investigated with almost the same copolymer graft contents but short or long highly permeable grafts. Their properties are discussed in terms of structure–property relationships for the sorption and pervaporation of the targeted azeotropic mixture. It is shown that the sorption properties are mainly governed by the copolymer graft content. On the other hand, the pervaporation features are strongly influenced by the copolymer graft content and architecture. For the same copolymer graft contents, it appears that the copolymers with short grafts are more selective and less permeable than the copolymers with long grafts. This difference in permeation behaviour is ascribed to different copolymer microstructures. The less segregated short grafts are more constrained within the rigid cellulose acetate matrix and lead to pervaporation separation factors that are twice those of the corresponding copolymers with long grafts. A comparison with the related literature results also shows that these graft copolymers are amongst the best materials so far reported for the separation of the azeotropic mixture ETBE/EtOH and this approach appears really promising for the design of a wide range of new copolymers with outstanding features for this application. [Copyright &y& Elsevier]

Abstract: In order to enhance their resistance to polar solvents and their film forming ability compared to these of neat polyvinylpyrrolidone (PVP), water soluble copolymers which combined rather large PVP sequences with ammonium groups were obtained. Free radical copolymerization of 1-Vinyl-2-Pyrrolidone (NVP) with 3-(dimethylamino)propyl-methacrylamide (DMA) and 3-(methacrylamido)propyltrimethyl-ammonium, methylsulfate (TMA) was investigated in water at 68°C using a water soluble initiator (4,4′-azobis(4-cyanovaleric acid ACVA)). The copolymer samples obtained at low conversion levels (<10%) could not be recovered quantitatively for these particular copolymers. Therefore, a numerical integration modeling, accounting for change in copolymer composition with conversion, was preferred to determine the optimal reactivity ratios from experimental data obtained at moderate conversions. The reactivity ratios (system TMA–NVP: rTMA 4.47, rNVP 0.038, system DMA–NVP: rDMA 5.67, rNVP 0.37) proved a strong preferential incorporation of the methacrylamide monomers. The reactivity ratios were then used to estimate the copolymer sequence distributions. It is shown that rather large NVP sequences can be obtained with low TMA or DMA initial contents at moderate conversion. Moreover, these copolymers easily formed films which withstood polar solvents and could be readily cross-linked by thermal curing, opening interesting prospects for membrane separation systems. [Copyright &y& Elsevier]