Reactivity of 2,3-Dichloropropene in free-radical copolymerization reactions

The copolymers of 2,3-Dichloropropene with vinyl chloride, methyl methacrylate, and styrene of different compositions were obtained via free-radical copolymerization. The copolymerization constants for the comonomers were found from the dependence of the copolymer composition on the initial mixture content. An increase in the content of 2,3-Dichloropropene in the initial mixture was found to decrease the yield and intrinsic viscosity of the copolymer for all systems. The reactivity of 2,3-Dichloropropene in copolymerization reactions was assessed according to the reciprocals of the copolymerization constants of vinyl chloride, methyl methacrylate, and styrene, which indicate the reactivity of the dichlorinated monomer when interacting with comonomer radicals. It was found that 2,3-dichloropropene is the most active in the reaction with a styrene radical. However, its reactivity with a methyl methacrylate radical decreases by a factor of 0.88 as compared to the styrene radical. The lowest reactivity of 2,3-Dichloropropene is observed when interacting with a vinyl chloride radical. The synthesized copolymers can be further modified by replacing chlorine atoms with functional groups.

A Short-Cut Data Mining Method for the Mass Spectrometric Characterization of Block Copolymers

A new data mining approach as a short cut method is given for the determination of the copolymer composition from mass spectra. Our method simplifies the copolymer mass spectra by reduction of the number of mass peaks. The proposed procedure, namely the selection of the mass peaks, which is based on the most abundant peak of the mass spectrum, can be performed manually or more efficiently using our recently invented Mass-remainder analysis (MARA). The considerable reduction of the MS spectra also simplifies the calculation of the copolymer quantities for instance the number- and weight-average molecular weights (Mn and Mw, respectively), polydispersity index (Đ = Mw/Mn), average molar fraction (cA) and weight fraction (wA) of the comonomer A and so on. These copolymer properties are in line with those calculated by a reference method taking into account all the mass peaks of the copolymer distribution. We also suggest a highly efficient method and template for the determination of the composition drift by processing the reduced mass spectra.

Synthesis, Characterization and Antibacterial Application of Copolymers Based on N,N-Dimethyl Acrylamide and Acrylic Acid

Hydrogel copolymers based on N,N-dimethyl acrylamide (DMA) and acrylic acid (AAc) were synthesized using a solution polymerization technique with different monomer ratios and ammonium persulfate as an initiator. This paper investigates the thermal stability, physical and chemical properties of the hydrogel copolymer. Testing includes Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and elemental analysis (CHNS). The copolymer composition was determined by elemental analysis, and the reactivity ratios of monomers were calculated through linearization methods such as Fineman–Ross (FR), inverted Fineman–Ross (IFR), Kelen–Tudos (KT) and Mayo–Lewis (ML). Good agreement was observed between the results of all four methods. The ratio of r1 and r2 were 0.38 (r1) and 1.45 (r2) (FR), 0.38 (r1) and 1.46 (r2) (IFR), 0.38 (r1) and 1.43 (r2) (KT), and 0.38 (r1) and 1.45 (r2) (ML). Hydrogel copolymers exhibited good thermal stability, and SEM showed three-dimensional porous structures. Antibiotic-free and antibiotic-loaded hydrogels demonstrated antimicrobial properties against both Gram-positive and Gram-negative bacteria. As the ratio of DMA in hydrogel copolymer increased, the activity of copolymer against bacteria enhanced. The results indicated that these hydrogels have the potential to be used as antibacterial materials.

Superior Gas Barrier Properties of Biodegradable PBST vs. PBAT Copolyesters: A Comparative Study

As a bio-based counterpart of poly(butylene adipate-co-terephthalate) (PBAT), the well-known commercially available biodegradable aliphatic-aromatic copolyester, poly(butylene succinate-co-terephthalate) (PBST) has comparable physical and mechanical properties, but its gas barrier properties, which are very important for packaging material and mulch film applications, have not yet been reported in literature. In this paper, the O2, CO2 and water vapor barrier properties of PBST vs. PBAT were comparatively studied and reported for the first time. Theoretical calculation of O2 and CO2 permeation coefficients via group contribution method was also conducted. The barrier properties of PBST show clear copolymer composition dependence due to different contribution of BS and BT repeat units and composition-dependent crystallinity. Comparing with PBAT, PBST with close copolymer and three-phase (crystalline, amorphous, rigid amorphous) compositions shows 3.5 times O2 and CO2 and 1.5 times water vapor barrier properties. The slower segment movement and less free volume of PBST, and therefore slower gas diffusion in PBST, accounts for its superior O2 and CO2 barrier, while the better hydrophilicity of PBST counteracts partial contribution of slower segment movement so that the improvement in water vapor barrier is not as high as in O2 and CO2 barrier.

Effect of Crystallinity on the Properties of Polycaprolactone Nanoparticles Containing the Dual FLAP/mPEGS-1 Inhibitor BRP-187

Seven polycaprolactones (PCL) with constant hydrophobicity but a varying degree of crystallinity prepared from the constitutional isomers ε-caprolactone (εCL) and δ-caprolactone (δCL) were utilized to formulate nanoparticles. The aim was to investigate the effect of the crystallinity of the bulk polymers on the enzymatic degradation of the particles. Furthermore, their efficiency to encapsulate the hydrophobic anti-inflammatory drug BRP-187 and the final in vitro performance of the resulting NPs were evaluated. Initially, high-throughput nanoprecipitation was employed for the εCL and δCL homopolymers to screen and establish important formulation parameters (organic solvent, polymer and surfactant concentration). Next, BRP-187-loaded PCL nanoparticles were prepared by batch nanoprecipitation and characterized using dynamic light scattering, scanning electron microscopy and UV-Vis spectroscopy to determine and to compare particle size, polydispersity, zeta potential, drug loading as well as the apparent enzymatic degradation as a function of the copolymer composition. Ultimately, NPs were examined for their potency in vitro in human polymorphonuclear leukocytes to inhibit the BRP-187 target 5-lipoxygenase-activating protein (FLAP). It was evident by Tukey’s multi-comparison test that the degree of crystallinity of copolymers directly influenced their apparent enzymatic degradation and consequently their efficiency to inhibit the drug target.

Supercritical carbon dioxide as a tool for improving the biocompatible properties of biopolymer and tissue specific scaffolds for tissue engineering

Objective: to investigate the efficacy of supercritical carbon dioxide (sc-CO2) for enhancштп the biocompatibility of biopolymer scaffolds from biodegradable materials and tissue-specific scaffolds from decellularized porcine liver slices (PLSs) or fine porcine cartilage particles (FPCPs).Materials and methods. Biopolymer scaffolds of a polyoxy(butyrate-co-valerate) and gelatin copolymer composition, 4 mm in diameter and 80 mm in length, were formed by electrospinning (NANON-01A, MECC CO, Japan) and stabilized by incubation in glutaraldehyde vapor for 48 hours at room temperature. For decellularization, PLSs and FPCPs were incubated under periodic stirring in buffer (pH = 7.4) solutions of sodium dodecyl sulfate (0.1%) and Triton X-100 with increasing concentrations (1, 2, and 3%). Treatment in a sc-CO2 atmosphere was done at 150–300 bar pressure, 35 °C temperature, and 0.25–2.5 mL/min flow rate of sc-CO2 for 8–24 hours. 10% ethanol was introduced as a polarity modifier. Cytotoxicity was studied according to GOST ISO 10993-5-2011. The growth of NIH/3T3 in the presence of samples was studied using an interactive optical system IncuCyte Zoom.Results. The effect of the sc-CO2 flow rate and pressure, and the effect of addition of ethanol, on the biocompatibility of scaffolds was investigated. It was found that treatment at a low sc-CO2 flow rate (0.25 mL/min) does not achieve the required cytotoxicity. Complete absence of cytotoxicity in biopolymer scaffolds was achieved in the presence of 10% ethanol, at a sc-CO2 flow rate of 2.5 mL/min, 300 bar pressure and 35 °C temperature after 8 hours of treatment. Effective removal of cytotoxic detergents from decellularized liver occurs already at a 150-bar pressure and does not require the addition of ethanol. Adding ethanol to sc-CO2 eliminates not only the cytotoxic, but also the cytostatic effect of tissue-specific scaffolds.Conclusion. Sc-CO2 treatment is an effective way to enhance the biocompatibility of three-dimensional porous matrices produced using cytotoxic substances: bifunctional crosslinking agents for biopolymer scaffolds and surfactants in the case of tissue-specific matrices. Addition of ethanol as a polarity modifier improves the treatment efficiency by eliminating both cytotoxic and cytostatic effects.