Water-soluble copolymers of N-acryloyl-N′-ethylpiperazine (AcrNEP) with methyl methacrylate (MMA) were synthesized to high conversion by free-radical solution polymerization. The composition of the copolymers was determined using Fourier Transform Infra-red Spectroscopy (FTIR). Copolymers containing AcrNEP content above 44 mol% were readily soluble in water and exhibited the critical solution temperature behavior. The copolymers were strongly responsive to changes in pH of the external medium due to the presence of tertiary amine functions that could be protonated at low pH. The influence of various factors such as copolymer composition, pH, temperature, salt and surfactant concentration on the LCST of the copolymers were systematically studied. The intrinsic viscosity of the copolymers in dimethyl formamide decreased with increase in temperature due to a decrease in thermodynamic affinity between polymer chains and solvent molecules. The viscosity behavior of the copolymers in sodium chloride solution was similar to that of classical polyelectrolytes and hydrophobically modified polyacrylate systems. Full article

2-(Dimethylamino)ethyl methacrylate/styrene statistical copolymers (poly(DMAEMA-stat-styrene)) with feed compositions f_DMAEMA = 80–95 mol%, (number average molecular weights M_n = 9.5–11.2 kg mol⁻¹) were synthesized using succinimidyl ester-functionalized BlocBuilder alkoxyamine initiator at 80 °C in bulk. Polymerization rate increased three-fold on increasing f_DMAEMA = 80 to 95 mol%. Linear M_n increases with conversion were observed up to about 50% conversion and obtained copolymers possessed monomodal, relatively narrow molecular weight distributions (polydispersity = 1.32–1.59). Copolymers with f_DMAEMA = 80 and 90 mol% were also cleanly chain-extended with DMAEMA/styrene mixtures of 95 and 90 mol% DMAEMA, respectively, confirming the livingness of the copolymers. Copolymer phase behavior in aqueous solutions was examined by dynamic light scattering and UV-Vis spectroscopy. All copolymers exhibited lower critical solution temperature (LCST)-type behavior. LCST decreased with increasing styrene content in the copolymer and with increasing solution concentration. All copolymers were completely water-soluble and temperature insensitive at pH 4 but were more hydrophobic at pH 10, particularly copolymers with f_DMAEMA = 80 and 85 mol%, which were water-insoluble. At pH 10, LCST of copolymers with f_DMAEMA = 90 and 95 mol% were more than 10 °C lower compared to their solutions in neutral, de-ionized water. Block copolymers with two statistical blocks with different DMAEMA compositions exhibited a single LCST, suggesting the block segments were not distinct enough to exhibit separate LCSTs in water. Full article

Vesicles are widely used in technological applications including cosmetic products, in microencapsulation for drug delivery, as anticancer agents and in the technology of adhesives, paints and inks. The vesicle size and the surface charge are very important properties from a technological point of view. Thus, the challenge in formulation is to find inexpensive stable vesicles with well-defined sizes and to modulate the surface charge of these aggregates. In this work we analyze the effect of different polymers on the structural properties of vesicles of the biodegradable surfactant sodium bis(2-ethyl-hexyl) sulfosuccinate, Aerosol OT. Using fluorescence, conductivity, electrophoretic mobility and dynamic light scattering measurements we study the effect of the polymer nature, molecular weight and polymer concentration on the stability and the vesicle size properties. Results demonstrate that it is possible to modulate both the size and the electric surface charge of spontaneous vesicles of Aerosol OT by the addition of very small percentages of poly(allylamine) and poly(maleic anhydride-alt-1-octadecen). Full article

We present the characterization of commercially available Poly(hexamethylene biguanide) hydrochloride (PHMB), a polymer with biocidal activity and several interesting properties that make this material suitable as a building block for supramolecular chemistry and “smart” materials. We studied polymer structure in water solution by dynamic light scattering, surface tension and capacitance spectroscopy. It shows typical surfactant behavior due to amphiphilic structure and low molecular weight. Spectroscopic (UV/Vis, FT-NIR) and thermal characterization (differential scanning calorimetry, DSC, and thermogravimetric analysis, TGA) were performed to give additional insight into the material structure in solution and solid state. These results can be the foundation for more detailed investigations on usefulness of PHMB in new complex materials and devices. Full article

Responsive polymer brushes possess many interesting properties that enable them to control a range of important interfacial behaviours, including adhesion, wettability, surface adsorption, friction, flow and motility. The ability to design a macromolecular response to a wide variety of external stimuli makes polymer brushes an exciting class of functional materials, and has been made possible by advances in modern controlled polymerization techniques. In this review we discuss the physics of polymer brush response along with a summary of the techniques used in their synthesis. We then review the various stimuli that can be used to switch brush conformation; temperature, solvent quality, pH and ionic strength as well as the relatively new area of electric field actuation We discuss examples of devices that utilise brush conformational change, before highlighting other potential applications of responsive brushes in real world devices. Full article

Advances in polymer science have led to the development of novel drug delivery systems. Some polymers are obtained from natural resources and then chemically modified for various applications, while others are chemically synthesized and used. A large number of natural and synthetic polymers are available. In the present paper, only water soluble polymers are described. They have been explained in two categories (1) synthetic and (2) natural. Drug polymer conjugates, block copolymers, hydrogels and other water soluble drug polymer complexes have also been explained. The general properties and applications of different water soluble polymers in the formulation of different dosage forms, novel delivery systems and biomedical applications will be discussed. Full article

Star shaped segmented macromolecules constitute an interesting class of polymeric materials whose properties differ remarkably from those appearing in their linear counterparts. This review highlights the work done in the last decade, dealing with the self-assembly of star-shaped block copolymers and terpolymers of various topologies in aqueous media. This article focuses on a specific class of star shaped macromolecules designated as stimuli responsive. These stars bearblock/arms undergo sharp phase transitions upon responding to stimuli, such as temperature, pH, ionic strength and so forth. These transitions impose dramatic transformations on the morphology and, accordingly, in the functionality of the nanostructured associates. The number of arms, the specific functionality and topology of the different arm/blocks and the overall macromolecular architecture of the star polymer, significantly influence their behavior in terms of self-assembly and responsiveness. Full article

This article reviews the use of multifunctional polymers founded on high-molecular weight poly(ethylene glycol) (PEG). The design of new PEG derivatives assembled in a dendrimer-like multimeric fashion or bearing different functionalities on the same molecule is described. Their use as new drug delivery systems based on the conjugation of multiple copies or diversely active drugs on the same biocompatible support is illustrated. Full article