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Isobornyl Acrylate (isobornyl + acrylate)
Selected AbstractsQuantification of Grafting Densities Achieved via Modular "Grafting-to" Approaches onto Divinylbenzene MicrospheresADVANCED FUNCTIONAL MATERIALS, Issue 12 2010Leena Nebhani Abstract The surface modification of divinylbenzene (DVB)-based microspheres is performed via a combination of reversible addition fragmentation chain transfer (RAFT) polymerization and rapid hetero-Diels,Alder (HDA) chemistry with the aim of quantifying the grafting densities achieved using this "grafting-to" method. Two variants of the RAFT-HDA concept are employed to achieve the functionalization of the microspheres. In the first approach, the microspheres are functionalized with a highly reactive diene, i.e., cyclopentadiene, and are subsequently reacted with polystyrene chains (number-averaged molecular weight, Mn,=,4200,g,mol,1; polydispersity index, PDI,=,1.12.) that carry a thiocarbonyl moiety functioning as a dienophile. The functionalization of the microspheres is achieved rapidly under ambient conditions, without the aid of an external catalyst. The surface grafting densities obtained are close to 1.2,×,1020 chains per gram of microspheres. In the second approach, the functionalization proceeds via the double bonds inherently available on the microspheres, which are reacted with poly(isobornyl acrylate) chains carrying a highly dienophilic thiocarbonyl functionality; two molecular weights (Mn,=,6000,g,mol,1, PDI,=,1.25; Mn,=,26,000,g,mol,1, PDI,=,1.26) are used. Due to the less reactive nature of the dienes in the second approach, functionalization is carried out at elevated temperatures (T,=,60,°C) yet in the absence of a catalyst. In this case the surface grafting density is close to 7,chains,nm,2 for Mn,=,6000,g,mol,1 and 4,chains,nm,2 for Mn,=,26,000,g,mol,1, or 2.82,×,1019 and 1.38,×,1019,chains g,1, respectively. The characterization of the microspheres at various functionalization stages is performed via elemental analysis for the quantification of the grafting densities and attenuated total reflectance (ATR) IR spectroscopy as well as confocal microscopy for the analysis of the surface chemistry. [source] High-Strain Shape-Memory PolymersADVANCED FUNCTIONAL MATERIALS, Issue 1 2010Walter Voit Abstract Shape-memory polymers (SMPs) are self-adjusting, smart materials in which shape changes can be accurately controlled at specific, tailored temperatures. In this study, the glass transition temperature (Tg) is adjusted between 28 and 55,°C through synthesis of copolymers of methyl acrylate (MA), methyl methacrylate (MMA), and isobornyl acrylate (IBoA). Acrylate compositions with both crosslinker densities and photoinitiator concentrations optimized at fractions of a mole percent demonstrate fully recoverable strains at 807% for a Tg of 28,°C, at 663% for a Tg of 37,°C, and at 553% for a Tg of 55,°C. A new compound, 4,4,-di(acryloyloxy)benzil (referred to hereafter as Xini) in which both polymerizable and initiating functionalities are incorporated in the same molecule, was synthesized and polymerized into acrylate shape-memory polymers, which were thermomechanically characterized yielding fully recoverable strains above 500%. The materials synthesized in this work were compared to an industry standard thermoplastic SMP, Mitsubishi's MM5510, which showed failure strains of similar magnitude, but without full shape recovery: residual strain after a single shape-memory cycle caused large-scale disfiguration. The materials in this study are intended to enable future applications where both recoverable high-strain capacity and the ability to accurately and independently position Tg are required. [source] Siloxane Copolymers for Nanoimprint Lithography,ADVANCED FUNCTIONAL MATERIALS, Issue 1 2007P. Choi Abstract Presented here is the novel use of thermoplastic siloxane copolymers as nanoimprint lithography (NIL) resists for 60,nm features. Two of the most critical steps of NIL are mold release and pattern transfer through dry etching. These require that the NIL resist have low surface energy and excellent dry-etching resistance. Homopolymers traditionally used in NIL, such as polystyrene (PS) or poly(methyl methacrylate) (PMMA), generally cannot satisfy all these requirements as they exhibit polymer fracture and delamination during mold release and have poor etch resistance. A number of siloxane copolymers have been investigated for use as NIL resists, including poly(dimethylsiloxane)- block -polystyrene (PDMS- b -PS), poly(dimethylsiloxane)- graft -poly(methyl acrylate)- co -poly(isobornyl acrylate) (PDMS- g -PMA- co -PIA), and PDMS- g -PMMA. The presence of PDMS imparts the materials with many properties that are favorable for NIL, including low surface energy for easy mold release and high silicon content for chemical-etch resistance,in particular, extremely low etch rates (comparable to PDMS) in oxygen plasma, to which organic polymers are quite susceptible. These properties give improved NIL results. [source] Synthesis of high glass transition temperature copolymers based on poly(vinyl chloride) via single electron transfer,Degenerative chain transfer mediated living radical polymerization (SET-DTLRP) of vinyl chloride in waterJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 24 2009Jorge F. J. Coelho Abstract ,,,-di(iodo) poly(isobornyl acrylate) macroiniators (,,,-di(iodo)PIA) with number average molecular weight from Mn,TriSEC = 11,456 to Mn,TriSEC = 94,361 were synthesized by single electron transfer-degenerative chain transfer mediated living radical polymerization (SET-DTLRP) of isobornyl acrylate (IA) initiated with iodoform (CHI3) and catalyzed by sodium dithionite (Na2S2O4) in water at 35 °C. The plots of number average molecular weight vs conversion and ln{[M]0/[M]} vs time are linear, indicating a controlled polymerization. ,,,-di(iodo) poly(isobornyl acrylate) have been used as a macroinitiator for the SET-DTLRP of vinyl chloride (VCM) leading to high Tg block copolymers PVC-b-PIA-b-PVC. The dynamic mechanical thermal analysis of the block copolymers suggests just one phase indicating that copolymer behaves as a single material. This technology provides the possibility of synthesizing materials based on PVC with higher Tg in aqueous medium. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2009 [source] Comparative Study of the Solid,Liquid Interface Behavior of Amphiphilic Block and Block-Like CopolymersMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 3-4 2009Nikolay Bulychev Abstract Amphiphilic block and "block-like" copolymers based on poly(isobornyl acrylate) and poly(acrylic acid) were used as stabilizers for hydrophilic (titanium dioxide) and hydrophobic (copper phthalocyanine) pigments. As reflected by the dispersion stabilities and electrokinetic sonic amplitude (ESA) measurements, the molecular architecture of the copolymer is of great importance for its interaction with the pigment surface. It was observed that irrespective of polymer composition, block-like copolymers exhibit lower stabilization ability and quite different adsorption behavior in comparison to block copolymers with sharp block boundaries. Models for the adsorption behavior of both block and block-like copolymers are proposed. [source] | ||||||||||