Controllable Vesicular Size and Shape in Polymerization-Induced Self-assembly Aided by Aromatic Interactions

The size and shape of polymeric vesicles have great impact on their physicochemical and biological properties. Polymerization-induced self-assembly (PISA) is an efficient method to fabricate vesicles. In most PISA-cases, the formation of vesicles is driven by the solvophobic interactions which are lack of versatility on finely structural regulation. Herein, controlling vesicular size and shape is realized in PISA aided by aromatic interactions. Aromatic interactions between the membrane-forming blocks contribute to the augments of membrane tension which lead to the formation of smaller vesicles (as small as 70 nm), but overly enhanced aromatic interactions result in vesicle fusion rather than size decreasing. When the membrane tension is dominated by aromatic interactions and meanwhile high enough to overcome the energetic barriers of fusion, the aromatic interactions drive vesicle fusion in a directional manner to form tubular structures. The precise regulation of vesicular size and shape in PISA would pave the way to fabricate vesicles for a series of size/shape-dependent applications.

Responsive Adsorption of N-Isopropylacrylamide Based Copolymers on Polymer Brushes

We investigate the adsorption of pH- or temperature-responsive polymer systems by ellipsometry and neutron reflectivity. To this end, temperature-responsive poly (N-isopropylacrylamide) (PNIPAM) brushes and pH-responsive poly (acrylic acid) (PAA) brushes have been prepared using the “grafting onto” method to investigate the adsorption process of polymers and its reversibility under controlled environment. To that purpose, macromolecular brushes were designed with various chain lengths and a wide range of grafting density. Below the transition temperature (LCST), the characterization of PNIPAM brushes by neutron reflectivity shows that the swelling behavior of brushes is in good agreement with the scaling models before they collapse above the LCST. The reversible adsorption on PNIPAM brushes was carried out with linear copolymers of N-isopropylacrylamide and acrylic acid, P(NIPAM-co-AA). While these copolymers remain fully soluble in water over the whole range of temperature investigated, a quantitative adsorption driven by solvophobic interactions was shown to proceed only above the LCST of the brush and to be totally reversible upon cooling. Similarly, the pH-responsive adsorption driven by electrostatic interactions on PAA brushes was studied with copolymers of NIPAM and N,N-dimethylaminopropylmethacrylamide, P(NIPAM-co-MADAP). In this case, the adsorption of weak polycations was shown to increase with the ionization of the PAA brush with interactions mainly located in the upper part of the brush at pH 7 and more deeply adsorbed within the brush at pH 9.

The heat capacities and critical behaviors of binary ionic solutions

The screening of both Coulombic forces and solvophobic interactions increased with relative permittivity, εr,c.

Aggregation of cyclic polypeptoids bearing zwitterionic end-groups with attractive dipole–dipole and solvophobic interactions: a study by small-angle neutron scattering and molecular dynamics simulation

The aggregation behavior of cyclic polypeptoids has been studied using experiments and simulations.

Complexation of Calix[4]arene bis-Hydroxymethylenediphosphonic Acid with Amino acids. Binding Constants Determination by RP HPLC Method

Host-Guest complexation of calixarene-bis-hydroxymethylenediphosphonic acid with 17 amino acids in water solution had been studied by the RP HPLC and molecular modelling methods. It had been shown the binding constants of the complexes are depended on the nature of the amino acid residue, log P and pKa of the acids. The complexation is mainly determined by the electrostatic interactions between the positively charged nitrogen atom of the amino acid and the negatively charged oxygen atom of phosphonic acid residue of the calixarene, the Host-Guest p-p, СН-p and solvophobic interactions.