Synthesis and Characterization of Chitosan-Acrylic Acid Based Hydrogels and Investigation the Properties of Bilayered Design With Incorporated Alginate Beads

The paper presents the synthesis of hydrogels via free-radical polymerization, based on Chitosan (CS) grafted with Acrylic acid (AA), using a two-step procedure. Free-radical polymerization has given strong hydrogels with compact structure, dominant elastic behavior and long linear viscoelastic region. The results of rheological studies have shown that obtained hydrogels have significantly improved mechanical properties in comparison to chitosan hydrogels obtained by other sustainable methods. A step forward in the investigation of the potential application of chitosan hydrogels in wound dressing systems has been made by preparation of the bilayer design by embedding a layer of active compound-loaded alginate beads into the contact surface between two conjoined units of CS/AA hydrogels. Wild garlic (Allium ursinum L.) dried extract was used as an active compound because of its antimicrobial activity and green properties. This system has demonstrated pH-dependent release of extract and higher shear elastic modulus values than ordinary disc gels. A conducted study has given preliminary results for the possible application of bilayer chitosan - based hydrogels in wound dressing systems and represents the first step towards extrapolating the proposed design across other application fields.

The Influence of Synthesis Method on Characteristics of Buffer and Organic Solutions of Thermo- and pH-Responsive Poly(N-[3-(diethylamino)propyl]methacrylamide)s

Thermo- and pH-responsive poly(N-[3-(diethylamino)propyl]methacrylamide)s were synthesized by free radical polymerization and RAFT polymerization. The molar masses of the samples were 33,000–35,000 g∙mol−1. Investigations of the dilute solutions showed that the prepared samples were flexible chain polymers. The behavior of the synthesized polymers in the buffer solutions was analyzed by turbidity and light scattering at a pH range of 7–13 and a concentration range of 0.0002–0.008 g·cm−3. When the concentrated solutions were at a low temperature, there were macromolecules and aggregates, which were formed due to the interaction of hydrophobic units. For the investigated samples, the lower critical solution temperatures were equal. The phase separation temperatures decreased as pH increased. The influence of polydispersity index on the characteristics of the samples in the solutions was analyzed. The radii of molecules of poly(N-[3-(diethylamino)propyl]methacrylamide) obtained by RAFT polymerization at this temperature at the onset and end of the phase separation interval were lower than ones for samples synthesized by conventional free radical polymerization.

Insertion of Degradable Thioester Linkages into Styrene and Methacrylate Polymers

The thionolactone 3,3-dimethyl-2,3-dihydro-5H-benzo[e][1,4]dioxepine-5-thione (DBT) is shown to homopolymerize and, for the first time, copolymerize with styrene and methacrylates, introducing degradable thioester backbone functionality. The rapid copolymerization with styrene was exploited to produce copolymers through free-radical polymerization in a starve-fed semi-batch setup. The copolymerization of DBT with tert-butyl methacrylate under RAFT conditions was hypothesized to involve selective retardation of DBT-terminal chains that led to a more uniform distribution of degradable thioester linkages between chains. Surprisingly, the aminolysis of DBT homopolymers was accompanied by the intramolecular ether cleavage within the primary degradation product leading to the formation of 2,2-dimethylthiirane and salic-ylamides.

Fluoroponytailed Ionic Liquids as Co-Porogens for Poly(butyl methacrylate-co-ethylene dimethacrylate) Monolithic Supports for Thin Layer Chromatography

Porous layered monolithic substrates of poly(butyl methacrylate-co-ethylene dimethacrylate) were synthesized via UV initiated free radical polymerization in presence of fluoroponytailed ionic liquids as co-porogenic constituents. The effects of the type...

Synthesis, Characterization and Antimicrobial studies of N-tert-amyl acrylamide (NTA) and 7-methacryloyloxy-4- methylcoumarin (MACU) Copolymers

Copolymers of N-tert-amylacrylamide (NTA) and 7-methacryloyloxy-4-methylcoumarin (MACU) were prepared by free radical polymerization in DMF at 600C using AIBN as an initiator. The copolymer compositions were determined by 1H-NMR analysis. The reactivity ratios of monomers were determined by Fineman-Ross (FR) (r1 = 1.33 and r2 = 0.60), KelenTudos (KT) (r1 = 1.33and r2 = 0.59). The r1.r2 = 0.798 indicated the formation of random copolymers.Tg found to increasing feed content of MACU. The antimicrobial studies showed that the copolymers are active against both Bacteria and Fungi.