Structure and Phase Behavior of Interpolyelectrolyte Complexes of PDADMAC and Hydrophobically Modified PAA (HM‐PAA)

Abstract

By combining oppositely charged polydiallyldimethylammonium chloride (PDADMAC) and sodium polyacrylate (NaPA), interpolyelectrolyte complexes (IPECs) can be formed in aqueous solution. Such IPECs are studied for rather short NaPA and under variation of the Mw of PDADMAC. The focus is on elucidating the effect of having a hydrophobic modification of the NaPA, which is introduced by having 10 mol% of the monomeric units substituted by ones carrying a dodecyl alkyl chain. This modification renders the complexes more hydrophobic, which is seen in the fact that precipitation of the complexes occurs at a lower mixing ratio and the biphasic region is also wider. The structures of the soluble IPECs are studied by a combination of light and neutron scattering (SANS). It is observed that the complexes formed possess typical radii of gyration of ≈30–40 nm, which become somewhat smaller with increasing length of the PDADMAC chain. The SANS data can be described well with the Beaucage model for complexes, where locally small hydrophobic domains of cylindrical shape are formed, whose persistence length decreases with increasing content of NaPA in the complexes. In contrast no such structures are seen for NaPA without the hydrophobic modification. The cylindrical domains are then arranged within larger‐sized clusters of 30–40 nm, which become more compact with reduced length of the PDAMAC chains. The structure of the IPECs is largely determined by the presence of the hydrophobic modification of the NaPA and is further controlled by the length of the hydrophobic modification. Such IPECs of controlled structure, relatively small size, and containing hydrophobic domains are potentially interesting as delivery systems due to having domains of variable polarity.

Comprehensive Dynamics in a Polyelectrolyte Complex Coacervate

“…Fares et al found R g in a PEC to be independent of salt concentration, in contrast to the typical response of individual polyelectrolytes, possibly a consequence of the high Pol + Pol – charge density (>1 M) within PECs. SANS studies of PECs report a “low q upturn,” attributable to density fluctuations approaching the 1 μm length scale, although the materials remain transparent to the eye. ,,, This long-range feature, probably not a result of thermal fluctuations, as it changes little with temperature (Figure S4), may be due to weak microphase separation between deuterated and nondeuterated polymers. The negligible temperature dependence of coil size in Figure S4 is similar to that found in neutral polymers under θ-conditions.…”

Advancements in Synthesis Strategies and Optoelectronic Applications of Bio-Based Photosensitive Polyimides

“…Tis method of postpolymerization modifcation of PAA has its own advantages in selecting diferent photosensitive properties and controlling the number and position of photosensitive functional groups. However, some undesirable side reactions are inevitable during the modifcation [53][54][55]. Moreover, because it requires extra steps to introduce photosensitive groups, it causes unnecessary waste of time and cost.…”

A Comparison of Interpolyelectrolyte Complexes (IPECs) Made from Anionic Block Copolymer Micelles and PDADMAC or q-Chitosan as Polycation

“…Lately, in our group, Kuzminskaya et al [18] reported a study about interpolyelectrolyte complexes of PDADMAC and PA, which mainly focused on the effect of the hydrophobic modification of PA on the structure and phase behaviour of complexes formed with PDADMAC, covering a wide range of molecular weight. The hydrophobic modification of PA was obtained by having 10 mol% monomeric units substituted by ones from a dodecyl alkyl acrylate chain.…”