Radical polymerization in micelles of surface-active monomers

Photo- and thermoinitiated radical polymerization was investigated in solution and micelles of cationic surface-active monomers in water. Kinetics of this process depend on the structure of micelles. Polymerization proceeds in aqueous solution of monomers, in their lamellae and spheric micelles, but doesn't occur in anisotropic ones. The polymerization rate in spheric micelles increases with the decrease of counterion size in the “head” and/or the length of the “tail” in monomer molecule. This results from the decrease of the rate of bimolecular termination reaction due to the increase of the density of micelles.     

A multi-criteria decision model for assessing health and self-care ability

Central European Journal of Operations Research - Population ageing together with the greater prevalence of multimorbidity add to the need for and complexity of healthcare services. This makes it...     

A Novel Type of Crown Ether‐Containing Metal Ions Optical Sensors Based on Polymer‐Stabilized Cholesteric Liquid Crystalline Films

For the first time, the films based on polymer‐stabilized cholesteric composites containing crown ether fragments with the optical properties sensitive to the complexation with potassium and barium ions were obtained. The complexation with these ions leads to blue spectral shift of the selective light reflection of planar cholesteric texture of composite films. Peculiarities of spectral changes and kinetics of selective light reflection shift were studied. The proposed approach can be used for the creation of the effective and selective sensor materials for different ions or groups of ions.     

Photodynamic Therapy Minimally Affects HEMA-DMAEMA Hydrogel Viscoelasticity

Soft matter implants are a rapidly growing field in medicine for reconstructive surgery, aesthetic treatments, and regenerative medicine. Though these procedures are efficacious, all implants carry risks associated with microbial infection which are often aggressive. Preventative and responsive measures exist but are limited in applicability to soft materials. Photodynamic therapy (PDT) presents a means to perform safe and effective antimicrobial treatments in proximity to soft implants. HEMA-DMAEMA hydrogels are prepared with the photosensitizer methylene blue included at 10 and 100 µM in solution used for swelling over 2 or 4 days. Thirty minutes or 5 h of LED illumination at $9.20\frac{mW}{c{m}^2}$ is then used for PDT-induced generation of reactive oxygen species in direct contact with hydrogels to test viable limits of treatment. Frequency sweep rheological measurements reveal minimal overall changes in terms of loss modulus and loss factor but a statistically significant drop in storage modulus for some PDT doses, though within the range of controls and biological variation. These mild impacts suggest the feasibility of PDT application for infection clearing in proximity to soft implants. Future investigation with additional hydrogel varieties and current implant models will further detail the safety of PDT in implant applications.     

The PVA‐PAAN intrapolymer complexes as sensors with optical response

Sorbtion of some impurities from aqueous solutions by polymer complex poly(vinylalcohol) with poly(acrylamide) grafted copolymers (PVA‐PAA_N) was studied by means of spectrophotometry and steady‐state fluorescence methods. The experiments showed that the PVA‐PAA_N films effectively sorbs impurities molecules of average benzene ring from water. Simultaneously, the processes of polymer films dissolving in water take place. The thermal annealing (with the help of special methods) PVA‐PAA_N film gives a possibility to obtain non‐dissolving polymer films which possess high sorbtion ability. Such films are proposed to be used as the sensors with optical response.