Hou-Hsein Chu

The stabilization effect of mixed-surfactants in the emulsion polymerization of styrene

SummaryThe emulsion polymerization of styrene was performed at 50°C with a mixture of anionic and nonionic surfactants using different surfactant concentrations. In the single-surfactant systems, a proportional relationship was observed between the total particle surface area per cm3 of aqueous solution at 90% conversion (TS) and the amount of surfactant used for each polymerization. For mixed-surfactant systems an additivity was established between the TS value and surfactant composition. The study of the particle size data from low to high conversion showed that the particle number changed with conversion.

The stabilization effect of mixed-surfactants in the emulsion polymerization of n-butyl acrylate

SummaryUsing a blend of anionic and nonionic surfactants, the emulsion polymerization of n-butyl acry late was conducted at 50°C. The total particle surface area per cm2 of aqueous solution (TS) at 90% conversion was found to be proportional to the amount of surfactant (E) used in the single-surfactant systems. A relationship close to additive exists between the TS value and the E of each surfactant used. For most of the recipes, the latex particles were uniform throughout the polymerization. However, in some recipes, the particle number varied during the polymerization.

Reactive compatibilization of poly(lactic acid)/polyethylene octene copolymer blends with ethylene-glycidyl methacrylate copolymer

Abstract A melt blending process was used to prepare poly(lactic acid) (PLA)/metallocene catalyzed polyethylene octene copolymer (POE) blends in order to toughen PLA. A commercialized ethylene-glycidyl methacrylate copolymer (EGMA) was applied as a compatibilizer to improve the dispersion and interaction of dispersed POE to the PLA matrix. The results showed that chemical interaction seems to be the driving force for reinforcing the compatibility between PLA and POE, and also the dispersion of POE into the PLA matrix domain. With the incorporation of 10 phr EGMA in the blends, POE was well-dispersed at a sub-micrometer scale within the PLA matrix, indicating better interfacial compatibility between PLA and POE. The impact strength test revealed that POE could significantly toughen PLA containing EGMA in the blends, up to no-break level regarding unnotched Izod impact strength at 10 phr EGMA content. With the increase of EGMA content, the blends showed lower tensile strength, but higher elongation at break due to the elastomeric characteristics of EGMA. When 10 phr of the EGMA was incorporated into the blends, its elongation at break reached 54.5%, 10.7 times that of neat PLA at 5.1%. The melt viscosity of compatibilized blends containing 10 phr EGMA increased by more than 50% in comparison with the non-compatibilized blend, which implied a good interfacial interaction between the PLA and POE interface.

Synthesis, crystal structure, optical and electrochemical properties of 9,10-dihydroxybenzo[h]quinoline

Abstract9,10-Dihydroxybenzo[h]quinoline (1), a 10-hydroxybenzo[h]quinoline (2) derivative, was synthesized and characterized by 1H NMR, 13C NMR, UV–vis and fluorescence spectra, and single-crystal X-ray diffraction. Compound 1 possesses an intramolecular six-membered-ring hydrogen bond, from which excited-state intramolecular proton transfer (ESIPT) takes place from the phenolic proton to the pyridinic nitrogen, resulting in a proton-transfer tautomer emission of 650 nm in dichloromethane. Its molecular geometry in the ground state has also been calculated using density functional theory (DFT) at the B3LYP/6-31G** level and compared with its crystal structure. Results show that the optimized geometry can well reproduce the crystal structure. Furthermore, both absorption and emission spectra of 1 and 2 were calculated using time-dependent DFT (TD-DFT) calculations, and were in good agreement with the experimental results. Graphical AbstractA 10-Hydroxybenzo[h]quinoline derivative, namely, 9,10-dihydroxybenzo[h]quinoline (1) was synthesized and fully characterized. Compound 1 possesses an intramolecular six-membered-ring hydrogen bond, from which ESIPT takes place, resulting in a proton-transfer tautomer emission of ~650 nm in aprotic solvents.

Removable acrylic pressure-sensitive adhesives activated by UV-radiation

Photo-activated removable acrylic pressure-sensitive adhesives (PSAs) were prepared by mixing a preformed polyacrylate resin with a multifunctional crosslinker, such as ethylene glycol dimethylacrylate (EGDMA), bisphenol A ethoxylate diacrylate (BAED), or trimethylolpropane triacrylate (TMPTA), and followed by a UV-curing process after film coating. The UV-curing process extensively increases the cohesive strength of PSA by increasing its molecular chain length, and the PSA can be removed from the substrate cleanly. The release of the PSA film can also be set to a requested time by applying a UV-curing process. It is shown that certain recipes with a combination of crosslinker and UV light showing excellent removability, such as using BAED with Irgacure 907, or EGDMA with Darocur 1173.

Effect of Surfactant Configurations on Miniemulsion Polymerization

In the adsorbed state, the molecular area (A c ) of fatty alcohol (FA) decreases and the hydrodynamic layer thickness (δ) of mixedsurfactant (FA + sodium dodecyl sulfate, SDS) increases with increasing alkyl chain length of FA. In bulk solution, the hydrodynamic volume of mixed-surfactant (FA+ SDS) increases with increasing alkyl chain length of FA. In both states the FAs were solubilized by SDS. These results reflect that a FA with a shorter alkyl chain length can stabilize a larger total particle surface area on latex and form smaller particles. The increase in the content of FA leads to increases in δ and particle size, and a decrease in polymerization rate. It may be plausible to consider that the FA has a rather rigid configuration in water. The degree to which the size of monomer droplets can be reduced may be related to the rigidity of the FA

Inverse Dispersion Polymerization Using Surfactant Mixtures Containing PS-b-PDMS

The diblock copolymer, polystyrene-b-poly (dimethylsiloxane) (PS-b-PDMS) with given block chain lengths, was prepared by the anionic polymerization. Phase separation was observed in cast films for the block copolymer with long enough block chain lengths in both blocks. The inverse dispersion polymerizations of MMA, EA and AA were conducted in cyclohexane in the presence of some water. Different surfactant combinations of PS-b-PDMS, polyoxyethylene nonylphenyl ether with EO number of 40 (Pannox 140, PA), and sodium dodecyl sulfate (SDS) were used. Two kinds of porous sphere formation mechanisms were involved: one formed small primary (latex) particles in the early stage and aggregated at later stage, while the other formed the much larger primary particles with hollow structures.

Water-borne Acrylic Pressure-Sensitive Adhesives Prepared by Using Cationic Surfactant

The latex pressure-sensitive adhesive (PSA) was prepared successfully by using cationic surfactant (cetyltrimethylammonium bromide, CTAB) in the emulsion copolymerization of methyl methacrylate (MMA) and 2-ethylhexyl acrylate (2-EHA) at 65°C. The latex prepared by using cationic surfactant exhibited quite high a viscosity (the relative viscosity being as high as 7,700), much higher than that prepared by using anionic surfactant (sodium dodecyl sulfate, SDS). Besides, different surfactant systems produced the adhesives having tremendously different values in intrinsic viscosity, tack, shear strength and peel strength.

Characteristics of emulsion polymerization of cyclohexyl methacrylate

SummaryA correlation between the particle size and the amounts of surfactants was found to fit well for the mixed-surfactant system of sodium dodecyl sulfate (SDS) and Emulphogene BC-840 (a nonionic surfactant) using in the emulsion polymerization of cyclohexyl methacrylate (CHMA) at 50°C. The formation of microglobules at early conversion was found. The effect of initiator (K2S2O6) content and the water solubility of CHMA and PCHMA were also studied.