Thermo-induced multistep assembly of double-hydrophilic block copolypeptoids in water

Stimulus-Responsive Polymers Based on Polypeptoid Skeletons

Polypeptoids have attracted a lot of atteSDntion because of their unique structural characteristics and special properties. Polypeptoids have the same main chain structures to polypeptides, making them have low cytotoxicity and excellent biocompatibility. Polypeptoids can also respond to external environmental changes by modifying the configurations of the side chains. The external stimuli can be heat, pH, ions, ultraviolet/visible light and active oxygen or their combinations. This review paper discussed the recent research progress in the field of stimulus-responsive polypeptoids, including the design of new stimulus-responsive polypeptoid structures, controlled actuation factors in response to external stimuli and the application of responsive polypeptoid biomaterials in various biomedical and biological nanotechnology, such as drug delivery, tissue engineering and biosensing.

Influence of Salt on the Self-Organization in Solutions of Star-Shaped Poly-2-alkyl-2-oxazoline and Poly-2-alkyl-2-oxazine on Heating

The water-salt solutions of star-shaped six-arm poly-2-alkyl-2-oxazines and poly-2-alkyl-2-oxazolines were studied by light scattering and turbidimetry. The core was hexaaza[26]orthoparacyclophane and the arms were poly-2-ethyl-2-oxazine, poly-2-isopropyl-2-oxazine, poly-2-ethyl-2-oxazoline, and poly-2-isopropyl-2-oxazoline. NaCl and N-methylpyridinium p-toluenesulfonate were used as salts. Their concentration varied from 0-0.154 M. On heating, a phase transition was observed in all studied solutions. It was found that the effect of salt on the thermosensitivity of the investigated stars depends on the structure of the salt and polymer and on the salt content in the solution. The phase separation temperature decreased with an increase in the hydrophobicity of the polymers, which is caused by both a growth of the side radical size and an elongation of the monomer unit. For NaCl solutions, the phase separation temperature monotonically decreased with growth of salt concentration. In solutions with methylpyridinium p-toluenesulfonate, the dependence of the phase separation temperature on the salt concentration was non-monotonic with minimum at salt concentration corresponding to one salt molecule per one arm of a polymer star. Poly-2-alkyl-2-oxazine and poly-2-alkyl-2-oxazoline stars with a hexaaza[26]orthoparacyclophane core are more sensitive to the presence of salt in solution than the similar stars with a calix[n]arene branching center.

Diblock copolypeptoids: a review of phase separation, crystallization, self-assembly and biological applications

Diblock copolypeptoids have the capacity to phase separate, crystallize, and self-assemble into a variety of nanostructures, which have shown great potential in a variety of biological applications.

Surface Properties and Structural Transformation Behaviors of mPEG-Maleic Rosin Copolymer in Water

mPEG (monomethoxy poly(ethylene glycol))-maleic rosin copolymer was successfully prepared. The surface properties of the copolymer were investigated by surface tension and resonance scattering techniques. The critical micelle concentration (CMC) was obtained. The adsorption behaviors and the conformational changes of the surfactant molecules at the air-water interface were described. The adsorption amount of state 1 presented a sinusoid shape and that of state 2 presented a sigmoid with the growth of П. The free energy of adsorption is more negative than that of micellization, thus, the surfactant molecules adsorb on the surface firstly, and then form micelles after saturation adsorption. Accordingly, structural transformation and aggregation behaviors of various concentration mPEG-maleic rosin copolymers with changing temperature were explored in water. The mPEG-maleic rosin chains experienced transformation from unimers to aggregates, to contracted aggregates, to cohesive aggregates with increasing temperature when the concentration is lower than CMC. This process is almost reversible with decreasing temperature. Transformation from micelle to aggregate with increasing temperature happened when the concentration is higher than CMC. The phenomena were assessed by DLS (dynamic light scattering) and SEM (scanning electron microscopy) techniques.