Influence of structure and solubility of chain transfer agents on the RAFT control of dispersion polymerisation in scCO2

RAFT dispersion polymerisation of methyl methacrylate is performed in scCO2 with 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) present as chain transfer agent (CTA) and surprisingly shows good control over PMMA molecular weight.

The Thermoviscosifying Behavior of Water-Soluble Polymer Based on Graft Polymerization of Pluronic F127 with Acrylamide and 2-Acrylamido-2-methylpropane Sulfonic Acid Sodium Salt

A new concept of thermoviscosifying polymers is proposed to address the problems about decreasing viscosity of polymer solution under high temperatures. However, existing thermoviscosifying polymers have complicated synthesis processes and high costs, and both of them restrict the wide practical applications of thermoviscosifying polymers. Although polyethers have the characteristics of thermal gelatinization, they just display thermoviscosifying behaviors only under extremely high concentrations (>15 wt %). Therefore, the graft copolymerization of the commercialized Pluronic F127 (PEO100-PPO65-PEO100) with acrylamide and 2-acrylamide-methylpropionic acid sodium salt was studied here. A series of graft modified polyether polymers were prepared and it was expected to get thermoviscosifying polymers with high molecular weights and low association temperatures. Several factors on thermoviscosifying behaviors were investigated, such as polymerization condition, polymer concentration, hydrophilic monomer, molecular structure and molecular weight. It was also proven that the apparent viscosity of polymer solution is influenced by polymer concentration, molecular weight of polymer, and content of anion groups.

Synthesis and thermal properties of poly(vinylcyclohexane)-b-poly(4-vinylpyridine) diblock copolymers prepared via RAFT polymerization

A series of novel poly(vinylcyclohexane)-b-poly(4-vinylpyridine) (PVCH-b-P4VP) diblock copolymers have been synthesized through a combination of anionic and RAFT polymerization techniques. Using this approach, end functionalized ω-hydroxy-polystyrene was used to yield ω-hydroxy-PVCH by hydrogenation followed by end-functionalization via an esterification reaction with 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid to yield PVCH-RAFT agent. The crossover propagation from PVCH-RAFT to 4VP displays living character and allowed generating diblock copolymers with well-defined molecular compositions. The characterization of the resulted polymers was performed using 1H nuclear magnetic resonance (NMR) and Fourier-transform infra-red (FT-IR) spectroscopies, size-exclusion chromatography with light-scattering detector (SEC-LS), and the thermal properties were studied using differential scanning calorimetry (DSC).

Detailed Study of Odor from Pig Buildings to Improve Understanding of Biotrickling Filter Performance

Recently, bioreactors, such as biotrickling filters, have been used to reduce odor and gas emissions from livestock facilities. Considerable efforts have already been made over the years to evaluate and improve the efficiencies of bioreactors used for this purpose; however, no study has yet been published that attempts to provide a thorough assessment of the performance of bioreactors in eliminating most (if not all) of the gases exhausted from swine facilities. Thus, this study was conducted to obtain a better understanding of the performance of biotrickling filters in treating swine odors by conducting a comprehensive evaluation of their overall performance in removing odor and gaseous components. Evaluating the performance of biotrickling filters using persistent gaseous components, i.e., those that remain in the treated air and contribute to the malodor, helps identify areas of the treatment system that can still be potentially improved. The gaseous components monitored were ammonia (NH3), hydrogen sulfide (H2S), and volatile organic compounds (VOCs). Samples were collected from two four-week trials using three laboratory-scale pig chamber and biotrickling filter systems. The NH3 and H2S concentrations were measured using non-dispersive infrared and ultraviolet fluorescence analyzers, respectively, while VOCs were collected using adsorption tubes and analyzed by a gas chromatograph coupled with a mass spectrometer and an olfactory detection port (GC-MS-O). Samples for odor measurement were also collected and analyzed using a dynamic olfactometer. Linear regression and odor index were used to identify the odorants that had the largest odor impacts. Odor index is an integrated parameter that expresses the combined contributions of odor intensity and hedonic tone to the perceived odor. Of the 176 VOCs identified in the samples, the odor components that had the largest odor impacts included butanoic acid, 3-methylbutanoic acid, 2-methylbutanoic acid, 2-methylpropionic acid, pentanoic acid, p-cresol, 2,3-butanedione, and dimethyl sulfide. However, most of these substances were almost completely eliminated in the biotrickling filters, except p-cresol and dimethyl sulfide. This implies that optimizing the removal of poorly water-soluble components, such as p-cresol and dimethyl sulfide, could further improve the performance of biotrickling filters in treating swine odors. Keywords: Biotrickling filters, Removal efficiency, Swine odor components.

Synthetic Polyampholytes Based Cryoprotective Agents by Reversible Addition Fragmentation Chain Transfer Polymerisation

ABSTRACTDimethyl sulfoxide (DMSO) and several naturally occurring polyols or their derivatives (like glycerol) have been used as cryoprotective agents (CPAs) for many years. However DMSO shows high cytotoxicity and affects differentiation of cells, so it needs to be removed immediately after thawing, whereas polyols are comparatively weaker cryoprotective agents. Furthermore, some types of cells are extremely sensitive to damage during freezing and thawing, so cannot be cryopreserved properly using current CPAs. So there is a great need to develop newer cryoprotective agents with lower cytotoxicity and high efficiency for many biological and medical purposes.Recently we showed that carboxylated poly-L-lysine, which is classified as a polyampholyte, has a cryoprotective effect on cells in solution without any other cryoprotectant. Polyampholytes are charged polymers with both positively and negatively charged groups.Therefore, in this research, we are developing a completely synthetic polyampholytes by radical polymerization and will try to elucidate the key parameters of cryoprotective properties. Here we chose reversible addition fragmentation chain transfer (RAFT) polymerization as the mode of polymerization as it is a kind of living polymerization method and can give control over the molecular weight and composition of the copolymer. We evaluated the livingness of the 1:1 copolymer with methacrylic acid (MAA) and 2-Dimethylamino ethyl methacrylate (DMAEMA) with 2-(Dodecylthiocarbonothioylthio)-2-methylpropionic acid as the RAFT agent and the polymer solution showed good cell viability of L929 cells after cryopreservation at 15% copolymer concentration.

Synthesis of ATRP macroinitiator based on synthetic cis- 1,4-polyisoprene and its application for graft polymerization of MMA

Modification of synthetic cis-1,4-polyisoprene (PI) into bromoalkylfunctionalized polyisoprene (PIBr), an ATRP macroinitiator, was investigated by two-step chemical reaction. The PI was partially epoxidized into epoxidized polyisoprene (EPI) using m-chloroperbenzoic acid, then the EPI was transformed into PIBr by reaction with 2-bromo-2-methylpropionic acid. The results from 1H NMR revealed that the addition product occurs in competition with epoxide ring rearrangement. The amount of bromoalkyl functionalized units was determined from 1H NMR spectra. The graft polymerization of MMA using ATRP technique from macroinitiator units in PIBr was investigated using three different ligands, i.e. N-(n-octyl)-2-pyridylmethanimine (NOPMI), N-(n-octadecyl)-2-pyridylmethanimine (NODPMI) and 1,1,4,7,7-pentamethyldiethylenetriamine (PMDETA), resulting in formation of graft copolymer of PI and PMMA. The PMMA grafts were successfully separated from the PI backbone using acidolysis for studying their number-average molecular weights (M̄̅̅n,SEC ) and polydispersity indexes (PDI). All of the ligands used give a increase of M̄̅̅n with MMA conversion. Comparing between 3 ligands, Cu(I)Br complexed with NOPMI shows first-order kinetic plot.