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Plastomers
Published in Anil K. Bhowmick, Current Topics in ELASTOMERS RESEARCH, 2008
Structurally, plastomers straddle the property range between elastomers and plastics. Plastomers inherently contain some level of crystallinity due to the predominant monomer in a crystalline sequence within the polymer chains. The most common type of this residual crystallinity is ethylene (for ethylene-predominant plastomers or E-plastomers) or isotactic propylene in meso (or m) sequences (for propylene-predominant plastomers or P-plastomers). Uninterrupted sequences of these monomers crystallize into periodic structures, which form crystalline lamellae. Plastomers contain in addition at least one monomer, which interrupts this sequencing of crystalline mers. This may be a monomer too large to fit into the crystal lattice. An example is the incorporation of 1-octene into a polyethylene chain. The residual hexyl side chain provides a site for the dislocation of the periodic structure required for crystals to be formed. Another example would be the incorporation of a stereo error in the insertion of propylene. Thus, a propylene insertion with an r dyad leads similarly to a dislocation in the periodic structure required for the formation of an iPP crystal. In uniformly back-mixed polymerization processes, with a single discrete polymerization catalyst, the incorporation of these interruptions is statistical and controlled by the kinetics of the polymerization process. These statistics are known as reactivity ratios.
Silicon Nanoparticles for Biophotonics
Published in Tuan Vo-Dinh, Nanotechnology in Biology and Medicine, 2017
There are relatively fewer examples of the application of hydrosilylation to free silicon nanoparticles, but the available studies suggest that the chemistry on free nanoparticles is similar to that on porous silicon and silicon wafers. Lie et a. [89] initiated hydrosilylation of silicon nanoparticles thermally, by refluxing porous silicon in a toluene solution of 1-octene, 1-undecene, or other molecules with a terminal alkene group. This yielded stable colloidal dispersions of individual nanocrystals. The hydrosilylation reaction was confirmed by Fourier transform infrared (FTIR) spectroscopy, and the approximate size of the resulting alkylated silicon nanocrystals was determined by time-of-flight mass spectrometry (TOFMS). Under UV excitation, the particles exhibited PL with a peak emission wavelength near 670 nm. In our group we have applied both thermally driven [14,29] and UV-photoinitiated hydrosilylation [15] to photoluminescent silicon particles produced by laser-induced vapor-phase decomposition of silane followed by HF–HNO3 etching. The hydrosilylation reaction was confirmed by FTIR and NMR spectroscopies. The PL of the particles was dramatically stabilized by the attachment of organic molecules to their surfaces. When we attached undecylenic acid to the particles via thermally driven hydrosilylation by refluxing in an ethanol solution, we observed significant oxidation in addition to the desired hydrosilylation reaction [14]. Particles with undecylenic acid or octadecene attached via thermally driven hydrosilylation remained susceptible to PL quenching by amines [29]. However, in more recent work, we have prepared denser monolayers of a variety of alkenoic compounds on nanoparticles with more complete hydrogen termination, and have seen improved resistance to PL quenching [15]. Li and Ruckenstein [103] used UV-driven hydrosilylation to attach acrylic acid to the surface of silicon nanoparticles prepared by this same method and were able to prepare a stable dispersion of them in water that maintained its PL. Warner et al. [49] used platinum-catalyzed hydrosilylation to attach allylamine to blue-emitting silicon quantum dots prepared by the reduction of SiCl4 with LiAlH4 in reverse micelles. They were also able to obtain a stable dispersion in water that maintained its PL. Wang et al. [104] used photoinitiated hydrosilylation to attach 1-octene or 1-hexene to silicon nanocrystals ultrasonically dispersed from porous silicon. They then used TDBA-OSu, an aryl-diazirine crosslinker, which created N-hydroxysuccinimidyl groups at the end of some or all of the surface-grafted alkyl chains. This allowed them to attach amine-functionalized DNA to the silicon nanoparticles. The oligonucleotide-conjugated silicon nanoparticles maintained their PL and formed stable dispersions in water. Thus, it appears that the wide range of strategies based on hydrosilylation reactions that have been developed for flat silicon wafer surfaces and porous silicon can, at least in many cases, also be applied to free silicon nanocrystals. This approach provides stable, covalent linkage of biologically relevant molecules to the nanoparticle surface, which should make the resulting nanostructures very robust.
A kinetic model and parameters estimate for the synthesis of 2-phenyloctane: a starting material of bio-degradable surfactant
Published in Indian Chemical Engineer, 2023
Sudip Banerjee, Md Aurangzeb, Amit Kumar
Here, we discuss the global symmetry number for protonation of 1-octene and 2-octene, alkylation of benzene and carbenium ion. The numbers of the 3-fold symmetry axis of 1-octene and 1-octene isomers (2-octene, 3-octene and 4-octene) are one and two, respectively. Therefore, the external global symmetry of 1-octene is 3, and 9 for 1-octene isomers. For both the 2-octylcarbenium and 3-octylcarbenium, the global symmetry number is nine due to the presence of two 3-fold symmetry axes. For the case of a 4-octylcarbenium ion, in addition to the axis, a plane of a symmetry element is present, so its global symmetry is 9/2. As far as the activated complex of 1-octene isomers is concerned, for 1-octene is 3 (one 3-fold symmetry axis), and 9/2 (it is divided by two because of the presence of 1 chiral carbon) for both 2-octene and 3-octene, and 9/4 (divided by four due to fact of 1 chiral carbon and one plane symmetry) for 4-octene.
Valorization of palm oil via cross-metathesis reaction using 1-octene
Published in Chemical Engineering Communications, 2022
The following research methods were systematically planned to carry out the cross metathesis of palm oil using 1-octene as shown in Equation (1) as well as the self- metathesis (SM) of 1-octene and triolein as shown in Equations (2) and (3) respectively. where A is triolein, B is 1-octene, C is 1-decene and D is glyceryl tri-9-decenoate where B is 1-octene, C is 1-decene and E is 1-butene. where A is triolein, C is 1-decene, G is 7-tetradecene, H is dimethyl-9-octadecenedioate and I is an ester.