Preparation of dendritic adamantane‐based polymers/layered silicate nanocomposites

An adamantane‐based atom transfer radical initiator (Adm‐Br) was prepared by the treatment of 1‐[[N‐[2‐Hydroxy‐l,l‐bis(hydroxymethyl)ethyl]amino]carbonyl]adamantane with bromopropionyl bromide. The resulting initiator was subsequently used in the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) to form (Adm‐p‐MMA), which was successfully used, as a macroinitiator, in further ATRP reactions with 3‐O‐methacryloyl‐1,2 5,6‐di‐O‐isopropylidene‐α‐d ‐glucofuranose (gly), a glycomonomer, to afford the Adm‐p‐MMA‐b‐gly polymer. The new Adm‐p‐MMA‐b‐gly polymer subsequently was employed to form a nanocomposite with chitosan‐modified, Nanofil clay (NC). The resulting Adm‐p‐MMA‐b‐gly/NC composite material was progressively hydrolyzed to regenerate the OH groups of the glucose units within the Adm‐p‐MMA‐b‐gly copolymer. The polymer/NC nanocomposites were characterized by X‐ray diffraction, thermal gravimetric analysis, differential scanning calorimetry, and transmission electron microscopy. POLYM. ENG. SCI., 54:2669–2675, 2014. © 2013 Society of Plastics Engineers     

Preparation of nanocoatings in the presence of precipitated CaCO3 fillers by UV-curing

Various methods were employed to prepare precipitated calcium carbonate (PCC) particles. Particle size and morphology were dependent on reaction conditions as well as temperature, reagents and stirring, either mechanical or by ultrasound probe sonication. Sonication helped to reduce the size of CaCO₃ particles as well as the precipitation time. Sonication was also used to disperse PCC particles in the UV-curable formulations as well as for preparation of the PCC. Formulations containing precipitated calcium carbonates and ground calcium carbonates in various grades were cured by a Mini UV-Cure device. Mechanical and thermal properties of films were characterized with a Dynamic Mechanical Analyzer (DMA). SEM analysis was also used to determine the shape and the size of the PCCs. Sonication decreased the precipitation time of calcium carbonate at least four times more than that of conventional precipitation procedures and the dispersion of particles in the formulations increased to a great extent.     

Investigation of PSt-MWCNT concentration on epoxyacrylate photopolymerization and conductivity of polymer films

Photopolymerization kinetics and conductivity changes of epoxyacrylate composites for various loading modified PSt-MWCNT weight fractions changing from 0.0025 to 0.2 wt.% were evaluated by performing photo differential scanning calorimetry (photo-DSC) and four point conductivity measurements. 0.2% PSt-MWCNT additive polymeric films had their electrical conductivity boosted by 6% more than non-additive polymeric films.     

Investigation of the photoinitiation of methyl methacrylate polymerization by 2-morpholino acetonaphthone

2-Morpholino acetonaphthone (MPM) was synthesized as a cleavable photoinitiator and the structure of the photoinitiator was confirmed by spectral and elemental analysis. The photoinitiation capability of MPM was demonstrated by using methyl methacrylate and a formulation containing multifunctional monomers.     

Photoinitiated polymerization of ethyl cyanoacrylate by phosphonium salts

The photoinitiated polymerization of ethyl cyanoacrylate (ECA) by benzyl triphenylphosphonium hexafluoroantimonate (BP⁺) and (anthracen-9-ylmethyl)triphenylphosphonium hexafluoroantimonate (MAP⁺) was studied. Zwitterionic and free radical mechanisms which involved homolytic and heterolytic decomposition of the phosphonium salts are discussed. The anthracene-sensitized photopolymerization of ECA was also demonstrated.     

The synthesis of water soluble cationic microgels by dispersion polymerization: Their performance in kaolin deposition onto fiber

The water soluble cationic microgels (CMG), intramolecularly cross‐linked cationic polymers of acrylamide (Am) and diallyldimethylammonium chloride (DADMAC), were synthesized with dispersion polymerization in the mixture of tert‐butanol (TBA)/water in the presence N,N′‐methylene‐bisacrylamide (MBA) as the cross‐linker, poly(N‐vinylpyrrolidone (PVP) as the stabilizer and 2,2′‐azobisisobutyronitrile (AIBN) as the initiator. The effects of monomer, cross‐linker, initiator, and stabilizer concentration on both particle size and molecular weight of CMG were investigated. The well dispersed polymer particles were produced in the range of poly dispersity index 1.1–1.4 and the molecular weight distribution with bimodal. Additionally, the efficiencies of two CMGs in the clay deposition on the bleached kraft fibers were investigated and compared with commercially widely used cationic polyacrylamide (CPAM) and poly‐diallyldimethylammonium chloride (poly‐DADMAC). The experiments showed that the CMGs were found as the effective flocculation agents and their efficiencies depended on their molecular weight and charge density. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

The effect of aromatic aminoalcohols on UV-cured films

It has been shown that the following three substituted α-aminoalcohols, 2-(N-methyl-N-phenylamino-1-phenyl) ethanol (1), 2-methyl-1-[4-(methylthio) phenyl-2-morpholino]propane-1-ol (2) and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-ol (3) fragment upon irradiation to give radicals which initiate polymerisation of trimethylolpropane triacrylate (TMPTA). The effectiveness of aminoalcohol (1) as an amelioration of oxygen inhibition was investigated and found to be less effective than N-methyldiethanolamine. Aminoalcohol (1) is a good synergist for isopropylthioxanthone, but due to the absorption characteristic of benzophenone, which absorbs poorly above 300 nm, it is not a suitable initiator.     

Ring opening polymerization of 3-semifluoro- and 3-bromomethyloxetanes to poly(2,2-substituted-1,3-propylene oxide) telechelics for soft blocks in polyurethanes

The synthesis of hydroxy-terminated poly(2,2-substituted-1,3-propylene oxide) polyoxetane telechelics and co-telechelics bearing semifluorinated (-CH₂OCH₂(CF₂)_nCF₃) and functional bromomethyl pendant groups is reported. Characterization utilized ¹H NMR spectroscopy, temperature modulated DSC (MDCS), and gel permeation chromatography (GPC). Analysis of relative reactivity ratios for a 1:1 3FOx to BrOx feed indicates that in the early stages of reaction BrOx-BrOx dyad mole fraction is below the statistically predicted amount. However, a model suggests that the final telechelic dyad composition at complete reaction is not very different from a statistical copolymer. The co-telechelics have low T_gs (−33 to −39 °C) and molecular weight in a desirable range (M_w≈3-5 k). Telechelics were incorporated in polyurethanes (PUs) with isophorone diisocyanate (IPDI) and butanediol (BD) as the hard block. Characterization of polyurethane composition and bulk properties by ¹H NMR, MDSC, and GPC is described. The new polyurethanes hold promise for a ‘reaction on polymer’ approach to polyurethanes with functional soft blocks.