• PDF / 521,249 Bytes
• 9 Pages / 595.276 x 790.866 pts Page_size
• 80 Downloads / 258 Views

DOWNLOAD

REPORT

---

Thermal stability of ionene polymers Valquı´ria Campos • Jo Dweck Cla´udio A. O. Nascimento • Celize M. Tcacenco

•

Received: 13 February 2012 / Accepted: 7 September 2012 / Published online: 30 September 2012 Ó Akade´miai Kiado´, Budapest, Hungary 2012

Abstract Two different cationic polymers of the same chemical type and with very similar chemical structures were reacted with a natural bentonite over a wide range of polymer/clay ratios. This study involved the synthesis of cationic aliphatic ammonium polyionenes, specifically 3,6-ionene and 3,6-dodecylionene. Ionenes are ion-containing polymers that contain quaternary nitrogen atoms in the main macromolecular chain as opposed to a pendant chain. The CHN content, basal spacing, and elemental composition of each of the polymer–clay complexes were analyzed by X-ray diffraction, X-ray fluorescence, and thermogravimetry. All the polycations reacted to form interlayer complexes with clay, which displaced more Na? and little Ca2?. Sodium and calcium were both present as interlayer cations in the clay and its complexes. The TG/DTG curves show that both polymers underwent thermal degradation in more than one stage. Specifically, 3,6-ionene was found to undergo two stages of decomposition and 3,6-dodecylionene undergo three stages. The behavior of the TG/DTG curves and the V. Campos (&) Environmental Engineering, UNESP – Univ Estadual Paulista and Center for Environmental Research and Training – CEPEMA, University of Sa˜o Paulo, Sa˜o Paulo, SP, Brazil e-mail: [email protected] J. Dweck School of Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil C. A. O. Nascimento Department of Chemical Engineering, Polytechnic School, University of Sa˜o Paulo and Center for Environmental Research and Training – CEPEMA, Sa˜o Paulo, SP, Brazil C. M. Tcacenco Center for Chemical Studies, UNIFIEO, Osasco, SP, Brazil

activation energy values suggest that 3,6-dodecylionene (E = 174,85 kJ mol-1) complexes have greater thermal stability than 3,6-ionene (E = 115,52 kJ mol-1) complexes. The mechanism of degradation suggests a direct interaction with the dodecyl chain containing 12 carbons, which are present in 3,6-dodecylionene but not in 3,6-ionene. Keywords Ionenes  Smectite  Clay–polymer complexes  Thermal analysis

Introduction In 1968, Rembaum et al. adopted the name ‘‘ionene’’ for polymers that contain ionic groups derived from aminocontaining monomers. The polymerization process typically resulted in a variety of cyclic species, in addition to the polymer product. The nomenclature of aliphatic, nonsegmented ionenes is associated with the number of methylene units from the monomers, namely the ditertiary amine and alkyl dihalide, respectively, i.e., x,y-ionene, where x = number of CH2 units in the diamine and y = number of CH2 units in the dihalide [1]. Bentonite is a clay mineral, belonging to the smectite group and contains essentially montmorillonite (2:1), which is largely used due to its availability and high cationic exchange capacity. Bentonite surface is neg