Colloids and Surfaces B: Biointerfaces 119 (2014) 47–54 Contents lists available at ScienceDirect Colloids and Surfaces B: Biointerfaces j o ur nal ho me pa ge: www.elsevier.com/locate/colsurfb Effect of pH and temperature upon self-assembling process between poly(aspartic acid) and Pluronic F127 Loredana E. Nita ∗ , Aurica P. Chiriac, Maria Bercea “Petru Poni” Institute of Macromolecular Chemistry, 41-A, Grigore Ghica Voda Alley, 700487 Iasi, Romania a r t i c l e i n f o Article history: Received 21 February 2014 Received in revised form 3 April 2014 Accepted 23 April 2014 Available online 4 May 2014 Keywords: Self-assembling Poly(aspartic acid) Pluronic F127 a b s t r a c t The present investigation was made in order to evaluate the capability of self-assembling of the two water soluble polymers, respectively, poly(aspartic acid) and Pluronic F127 into well interpenetrated mixture, and to evidence the connection effects intervened during polymer complex formation to exhibit good stability once formed, as well to understand and correlate the binding strength and the interval between better association domains. The effect of pH and temperature on the interpolymeric complex formation between poly(aspartic acid) and Pluronic F127 was studied by combining rheology with light scattering technique. The solution mixtures between poly(aspartic acid) and Pluronic F127 are Newtonian fluids for all ratios among them. Depending on the polymeric mixture composition and experimental temperature, positive or negative deviations of the experimental values from the additive dependence appear. An interesting behavior was registered around 1/1 wt. ratio between the two polymers, when the hydrodynamic diameter of the interpenetrated polymeric particles decreased suddenly. This allows us to conclude the formation of core–shell micelle structure with poly(aspartic acid) core and Pluronic F127 as shell, performed through strong interactions between polymers. This behavior was sustained by the increase of absolute value of zeta potential owing to the decrease of functional groups number at the surface of micelles. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Self-assembling is a strategy for materials preparation which can produce highly structured, compositionally defined, multi- component and multifunctional materials from a discrete set of molecular building blocks. Self-assembly has become very use- ful in chemistry and materials science for diverse applications, in fields ranging across electronic materials, synthetic biology, struc- tural materials, chemical biology, and biomaterials. Thus, through spontaneous self-assembly transitions of the initially disordered molecules, acquired by specific noncovalent interactions, pre- dictable supramolecular structures can be prepared. The forces that direct contribute to molecular self-assembly are weak intermolec- ular interactions between molecules in solution, which include hydrogen bonding, hydrophobic interactions, Coulombic interac- tions, -stacking, and van der Waals forces [1]. During preparation the self-assembling systems are highly dependent on solution conditions such as pH, ionic strength, con- centration, temperature, and solvent polarity. The self-assembling ∗ Corresponding author. Tel.: +40 232 217454; fax: +40 232 211299. E-mail address: lnazarie@yahoo.co.uk (L.E. Nita). processes enable the achievement of materials displaying complex combinations of molecular features. Multifunctional materials can be thus systematically assembled and optimized, even when multi- ple co-assembling constituents are present, compounds which are also able to be functionalized with ligands or chemical groups either post-assembly or pre-assembly. Soft condensed matters or biological systems are generally self-associated through weak forces, which are acting together being as well difficult to unravel their relative contributions. For instance, the aggregates formed in water by association between cationic and anionic polymers, or surfactants, become strongly hydrophobic and precipitate in many cases. Also, hydrophobic- ity results from the hydrogen bonds between a hydrogen donor and a hydrogen acceptor, such as non-dissociated polyacids and polyoxyethylene or polyethoxylated non-ionic surfactants. On the other hand, the polyacid ionization at high pH reduces or even destroys the ability to form hydrogen bonds [2]. Interpolymer com- plexes are also prepared based on attractive interactions between appropriate macromolecular chains dissolved in a common solvent. These complexes are mainly stabilized via electrostatic interactions in the case of a polyanion/polycation mixture, or through hydro- gen bonds between a polyacid (H-bond donor) and a polybase (H-bond acceptor). These complexes have long been known and http://dx.doi.org/10.1016/j.colsurfb.2014.04.023 0927-7765/© 2014 Elsevier B.V. All rights reserved.