The micellization and dissociation transitions of thermo-, pH- and sugar-sensitive block copolymer investigated by laser light scattering

Abstract

Abstract.A triple-stimuli responsive polymer, poly(3-acrylamidophenylboronic acid)-b-poly(N-isopropylacrylamide) (PAAPBA-b-PNIPAM), has been synthesized by reversible addition-fragmentation chain transfer polymerization. Temperature, pH, and fructose induced micellization and dissociation transition of block copolymer was investigated by a combination of static and dynamic laser light scattering. PAAPBA-b-PNIPAM copolymer self-assembles into micelles with PAAPBA block as core and PNIPAM as shell in lower pH aqueous solution at room temperature. Increasing the temperature causes the micelle to shrink due to the dehydration of PNIPAM segments at pH 6.2. After the elevation of solution pH from 6.2 to 10.0, the increase in the hydrophilicity of PAAPBA block leads to an expulsion of unimers from micelles. In addition, the fructose addition further enhances the dissociation of micelles. Our experiments demonstrate that the micelle to unimer transition process proceeds via the step-by-step sequential expulsion of individual chains.

Multi-Responsive Behaviors of Copolymers Bearing N-Isopropylacrylamide with or without Phenylboronic Acid in Aqueous Solution

“…Therefore, both copolymers were not easily ionized and remained uncharged forms in acidic solution, whereas they could be ionized to produce charged nanoparticles in neutral and alkaline media. Since apparent p K a of PBA and derivatives were approximate to 8.6 [ 18 ], AAPBA addition had largely potential to delay the ionization of PNAHT copolymers.…”

“…Because it is easy to change physical conditions of working solutions, DLS technique is often used to examine D H of PNIPAAm-mediated materials changed in response to the changes of environmental parameters, in order to illustrate the stimulus responses of intelligent composites [ 11 , 12 , 13 ]. Recently, scholars had also conducted prominent works in the synthesis of smart materials carrying NIPAAm and PBA, and further investigated their dual responses to temperature and glucose by means of the DLS technique [ 14 , 15 , 16 , 17 , 18 ]. It can be seen that PBA moieties are supposed to be modified on PNIPAAm backbone, making it easier to upgrade the thermosensitivity of PNIPAAm to multiple responses to temperature, pH and glucose, so their effective applications can be further expanded.…”

Imidazolium Quaternized Polymers Based On Poly(Chloromethyl Styrene) and their Complexes with FBS Proteins and DNA

“…Evidently, the polymer with the highest degree of quaternization forms aggregates of an open-structured morphology (solvent swelled structure), while the one with the lowest degree of quaternization forms more compact spherical nanostructures, due to the higher hydrophobicity of the main chain. [ 30 ] The apparent molecular weights (M w, app ) of QIm-PCMS2 aggregates is slightly higher than the one of QIm-PCMS1 (Table 3 ). The same holds for the aggregation numbers N w .…”

“…Consequently, there is a significant difference in the aggregates' shape of QIm‐PCMS2 ( ρ = 1.33) in comparison to QIm‐PCMS1 ( ρ = 0.50). Evidently, the polymer with the highest degree of quaternization forms aggregates of an open‐structured morphology (solvent swelled structure), while the one with the lowest degree of quaternization forms more compact spherical nanostructures, due to the higher hydrophobicity of the main chain . The apparent molecular weights () of QIm‐PCMS2 aggregates is slightly higher than the one of QIm‐PCMS1 (Table ).…”