The production of elemental sulfur from petroleum refining has created atechnological opportunity to increase the valorization of elemental sulfur by the creation of highperformance sulfur based plastics with improved thermomechanical properties,elasticity and flame retardancy.W ereport on asynthetic polymerization methodology to prepare the first example of sulfur based segmented multi-block polyurethanes (SPUs) and thermoplastic elastomers that incorporate an appreciable amount of sulfur into the final target material. This approach applied both the inverse vulcanization of S 8 with olefinic alcohols and dynamic covalent polymerizations with dienes to prepare sulfur polyols and terpolyols that were used in polymerizations with aromatic diisocyanates and short chain diols.Using these methods,anew class of high molecular weight, soluble blockcopolymer polyurethanes were prepared as confirmed by SizeE xclusion Chromatography,N MR spectroscopy, thermal analysis,a nd microscopic imaging. These sulfur-based polyurethanes were readily solution processed into large area free standing films where both the tensile strength and elasticity of these materials were controlled by variation of the sulfur polyol composition. SPUs with both high tensile strength (13-24 MPa) and ductility (348 %strain at break) were prepared, along with SPU thermoplastic elastomers (578 %s train at break) which are comparable values to classical thermoplastic polyurethanes (TPUs). The incorporation of sulfur into these polyurethanes enhanced flame retardancy in comparison to classical TPUs,w hich points to the opportunity to impart new properties to polymeric materials as ac onsequence of using elemental sulfur.
Design concepts of a newly developed multi-wavelength, micro Raman spectroscopy system for non-contact and non-destructive characterization of semiconductor materials and its performance are introduced. The system is designed to sequentially measure Raman signals under various excitation wavelengths without sample movement or calibration between switching of excitation wavelengths. Area maps of Raman shift, full-width-at-half-maximum (FWHM) and intensity from an advanced memory device were generated and stacked in the order of wavelength (or penetration depth). This unique display of Raman shift, FWHM and intensity, corresponding to crystalline stress, crystallinity and/or scattering probability provides powerful insights into the sample under characterization.
Multiwavelength room temperature photoluminescence (RTPL) and Raman spectroscopy were proposed as in-line monitoring techniques for characterizing the dielectric/Si interface. As an application example, ∼7.0 nm thick ultra-thin SiO 2 films on 300 mm Si wafers, prepared by various oxidation techniques and conditions, were characterized using multiwavelength RTPL and Raman spectroscopy. Specifically, overall quality of the ultra-thin SiO 2 /Si interface (including passivation characteristics) and Si lattice stress beneath SiO 2 films are investigated. The overall SiO 2 /Si interface quality was seen to be very dependent on oxidation technique and process conditions. Within wafer and wafer-to-wafer variations of SiO 2 /Si interface quality were successfully characterized by RTPL and Raman spectra measurements. For electrical analysis of SiO 2 /Si-based structures, non-contact corona charge-based, in-line (capacitance-voltage (C-V) and stress induced leakage current (SILC)) measurements were performed and compared with RTPL and Raman characterization results. Surprisingly, significant variations in RTPL intensity at and near the corona charge-based measurement sites, indicated that the corona-based electrical measurement technique, though non-contact, was indeed invasive. The effect of corona-charge based electrical measurements on SiO 2 /Si interface was permanent and even clearly visible from the back side of the wafer. RTPL intensity variations at and near the measurement sites remained, even after a forming gas anneal. As devices scale to smaller size and complexity of device structures increase, the importance of proper understanding and control of the dielectric/Si interface is increasing. Advanced metal-oxidesemiconductor (MOS) and metal-insulator-semiconductor (MIS) devices employ ultra thin dielectric gate layers. The physical dimensions are in the range of single digit to double digit nanometers. The effective oxide thickness (EOT) is significantly less than 10 nm. Pure SiO 2 or combinations of SiO 2 and SiN layers are typically used as gate dielectrics. Materials with high dielectric constant (high-k dielectrics) and metal gates are also frequently used, depending on chip design.Conventional interface characterization techniques, such as high resolution cross-sectional transmission electron microscopy (HRX-TEM), Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS), X-ray photoelectron spectroscopy (XPS) and noncontact electrical measurement tools (for example, I-V, C-V and carrier life-time measurements) are either destructive or invasive (including methods which are non-contact, but impact dielectric/Si interface quality).1-3 The purpose of all these characterization techniques is to gain useful insights into dielectric/Si in various dimensions or aspects. While the conventional characterization techniques provide very useful information on many properties of the dielectric/Si interface, they appear unable to provide additional clues to some puzzling dielectric/Si interface problems....
Organosulfur polymers, such as those derived from elemental sulfur, are an important new class of macromolecules that have recently emerged via the inverse vulcanization process. Since the launching of this new field in 2013, the development of new monomers and organopolysulfide materials based on the inverse vulcanization process is now an active area in polymer chemistry. While numerous advances have been made over the last decade concerning this polymerization process, insights into the mechanism of inverse vulcanization and structural characterization of the high-sulfurcontent copolymers that are produced remain challenging due to the increasing insolubility of the materials with a higher sulfur content. Furthermore, the high temperatures used in this process can result in side reactions and complex microstructures of the copolymer backbone, complicating detailed characterization. The most widely studied case of inverse vulcanization to date remains the reaction between S 8 and 1,3-diisopropenylbenzene (DIB) to form poly(sulfur-random-1,3-diisopropenylbenzene)(poly(S-r-DIB)). Here, to determine the correct microstructure of poly(S-r-DIB), we performed comprehensive structural characterizations of poly(S-r-DIB) using nuclear magnetic resonance spectroscopy (solid state and solution) and analysis of sulfurated DIB units using designer S−S cleavage polymer degradation approaches, along with complementary de novo synthesis of the sulfurated DIB fragments. These studies reveal that the previously proposed repeating units for poly(S-r-DIB) were incorrect and that the polymerization mechanism of this process is significantly more complex than initially proposed. Density functional theory calculations were also conducted to provide mechanistic insights into the formation of the derived nonintuitive microstructure of poly(S-r-DIB).
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