Influence of the comonomer structure and of the initial pH on the characteristics of polyelectrolyte complexes based on
- PDF / 556,363 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 49 Downloads / 219 Views
ORIGINAL PAPER
Influence of the comonomer structure and of the initial pH on the characteristics of polyelectrolyte complexes based on maleic acid copolymers Irina Popescu & Dana Mihaela Suflet & Marcela Mihai
Received: 24 May 2012 / Accepted: 13 August 2012 / Published online: 26 August 2012 # Springer Science+Business Media B.V. 2012
Abstract The interaction between some hydrophilic and hydrophobic maleic acid copolymers and a strong polycation, poly(diallyldimethylammonium chloride), at low concentration and different pH, with the formation of polyelectrolyte complex (PEC) dispersions, was the object of this study. Poly (maleic acid–alt–vinyl acetate) was used as hydrophilic copolymer and poly(maleic acid–alt–styrene) and poly(maleic acid–alt–2-vinylnaphthalene) were used as more hydrophobic copolymers. A special attention was given to the in-situ investigation by turbidimetry, potentiometry, and conductometry of the formed PECs and to their characterization after 24 h by optical density, dynamic light scattering and atomic force microscopy. Taking into account that the conformation of the copolymers is influenced by their neutralization degree, related to the solution pH, we had investigated the influence of this parameter on the PEC formation at pH06, where around half of the carboxylic groups are neutralized, and at pH010, at totally dissociated state. This study focused on the influence of the comonomer hydrophilic/hydrophobic nature, polyions mixing order, and starting pH of the solutions on the ratio of the complementary polyelectrolytes at the titration end-point and on the PEC particles size. Keywords Polyelectrolyte complexes . Maleic acid copolymers . pH . Mixing order
Introduction Polyelectrolyte complexes (PEC) are made by mixing solutions of oppositely charged polyelectrolytes. The attractive I. Popescu (*) : D. M. Suflet : M. Mihai “Petru Poni” Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda 41A, Iasi 700487, Romania e-mail: [email protected]
Coulomb interaction is the main driving force in PEC formation, but other secondary binding forces (hydrogen-bonding, van der Waals forces, charge-transfer or hydrophobic interactions) also play an important role. There are many papers that review the PECs formation characteristics and their characterization methods [1–5], as well as their applications as membrane with special separation properties [6] or as micro/nanocapsules [7]. PECs can have different morphology: solutionprecipitated PECs, quasi-soluble PECs (stable colloidal suspension), coacervates, physic hydrogels, and even polyelectrolyte multilayers. At relatively low concentrations and when one of the components is taken in excess, PEC formation can lead to stable colloidal dispersions. PECs as colloidal dispersion can be used as drug-carriers [8, 9], flocculants [10], auxiliary products in paper manufacturing [11], etc. The radical copolymerization of the maleic anhydride with vinylic or acrylic comonomers followed by the hydrolysis of the anhydride cycle leads to the maleic ac
Data Loading...
