Dithiophosphoric Acids for Polymer Functionalization.

Dithiophosphoric acids (DTPAs) are an intriguing class of compounds that are sourced from elemental sulfur and white phosphorus and are prepared from the reaction of phosphorus pentasulfide with alcohols. The electrophilic addition of DTPAs to alkenes and unsaturated olefinic substrates is a known reaction, but has not been applied to polymer synthesis and polymer functionalization. We report on the synthesis and application of DTPAs for the functionalization of challenging poly-enes, namely polyisoprene (PI) and polynorbornene (pNB) prepared by ring-opening metathesis polymerization (ROMP). The high heteroatom content within DTPA moieties impart intriguing bulk properties to poly-ene materials after direct electrophilic addition reactions to the polymer backbone introducing DTPAs as side chain groups. The resulting materials possess both enhanced optical and flame retardant properties vs the poly-ene starting materials. Finally, we demonstrate the ability to prepare crosslinked polydiene films with di-functional DTPAs, where the crosslinking density and thermomechanical properties can be directly tuned by DTPA feed ratios.

On the Mechanism of the Inverse Vulcanization of Elemental Sulfur: Structural Characterization of Poly(sulfur-random-(1,3-diisopropenylbenzene)).

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-sulfur-content 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 S8 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).

Synthesis of Deuterated and Sulfurated Polymers by Inverse Vulcanization: Engineering Infrared Transparency via Deuteration.

The synthesis of deuterated, sulfurated, proton-free, glassy polymers offers a route to optical polymers for infrared (IR) optics, specifically for midwave IR (MWIR) photonic devices. Deuterated polymers have been utilized to enhance neutron cross-sectional contrast with proteo polymers for morphological neutron scattering measurements but have found limited utility for other applications. We report the synthesis of perdeuterated d14-(1,3-diisopropenylbenzene) with over 99% levels of deuteration and the preparation of proton-free, perdeuterated poly(sulfur-random-d14-(1,3-diisopropenylbenzene)) (poly(S-r-d14-DIB)) via inverse vulcanization with elemental sulfur. Detailed structural analysis and quantum computational calculations of these reactions demonstrate significant kinetic isotope effects, which alter mechanistic pathways to form different copolymer microstructures for deutero vs proteo poly(S-r-DIB). This design also allows for molecular engineering of MWIR transparency by shifting C-H bond vibrations around 3.3 µm/3000 cm-1 observed in proteo poly(S-r-DIB) to 4.2 µm/2200 cm-1. Furthermore, the fabrication of thin-film MWIR optical gratings made from molding of deuterated-sulfurated, proton-free poly(S-r-d14-DIB) is demonstrated; operation of these gratings at 3.39 µm is achieved successfully, while the proteo poly(S-r-DIB) gratings are opaque at these wavelengths, highlighting the promise of MWIR sensors and compact spectrometers from these materials.

Sulfenyl Chlorides: An Alternative Monomer Feedstock from Elemental Sulfur for Polymer Synthesis.

A polymerization methodology is reported using sulfur monochloride (S2Cl2) as an alternative feedstock for polymeric materials. S2Cl2 is an inexpensive petrochemical derived from elemental sulfur (S8) but has numerous advantages as a reactive monomer for polymerization vs S8. This new process, termed sulfenyl chloride inverse vulcanization, exploits the high reactivity and miscibility of S2Cl2 with a broad range of allylic monomers to prepare soluble, high molar-mass linear polymers, segmented block copolymers, and crosslinked thermosets with greater synthetic precision than achieved using classical inverse vulcanization. This step-growth addition polymerization also allows for preparation of a new class of thiol-free, inexpensive, highly optically transparent thermosets (α = 0.045 cm-1 at 1310 nm), which exhibit among the best optical transparency and low birefringence relative to commodity optical polymers, while possessing a higher refractive index (n > 1.6) in the visible and near-infrared spectra. The fabrication of large-sized optical components is also demonstrated.

On the Fundamental Polymer Chemistry of Inverse Vulcanization for Statistical and Segmented Copolymers from Elemental Sulfur.

In this concept review, the fundamental and polymerization chemistry of inverse vulcanization for the preparation of statistical and segmented sulfur copolymers, which have been actively developed and advanced in various applications over the past decade is discussed. This concept review delves into a discussion of step-growth polymerization constructs to describe the inverse vulcanization process and discuss prepolymer approaches for the synthesis of segmented sulfur polyurethanes. Furthermore, this concept review discusses the advantages of inverse vulcanization in conjunction with dynamic covalent polymerization and post-polymerization modifications to prepare segmented block copolymers with enhanced thermomechanical and flame retardant properties of these materials.

Segmented Polyurethanes and Thermoplastic Elastomers from Elemental Sulfur with Enhanced Thermomechanical Properties and Flame Retardancy.

The production of elemental sulfur from petroleum refining has created a technological opportunity to increase the valorization of elemental sulfur by the creation of high-performance sulfur based plastics with improved thermomechanical properties, elasticity and flame retardancy. We report on a synthetic 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 S8 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, a new class of high molecular weight, soluble block copolymer polyurethanes were prepared as confirmed by Size Exclusion Chromatography, NMR spectroscopy, thermal analysis, and 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 % strain 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, which points to the opportunity to impart new properties to polymeric materials as a consequence of using elemental sulfur.

Unraveling the rheology of inverse vulcanized polymers.

Multiple relaxation times are used to capture the numerous stress relaxation modes found in bulk polymer melts. Herein, inverse vulcanization is used to synthesize high sulfur content (≥50 wt%) polymers that only need a single relaxation time to describe their stress relaxation. The S-S bonds in these organopolysulfides undergo dissociative bond exchange when exposed to elevated temperatures, making the bond exchange dominate the stress relaxation. Through the introduction of a dimeric norbornadiene crosslinker that improves thermomechanical properties, we show that it is possible for the Maxwell model of viscoelasticity to describe both dissociative covalent adaptable networks and living polymers, which is one of the few experimental realizations of a Maxwellian material. Rheological master curves utilizing time-temperature superposition were constructed using relaxation times as nonarbitrary horizontal shift factors. Despite advances in inverse vulcanization, this is the first complete characterization of the rheological properties of this class of unique polymeric material.

A facile template-free strategy for synthesizing hydroxymethyl-poly(3,4-ethylenedioxythiophene) nanospheres.

Hydroxymethyl-poly(3,4-ethylenedioxythiophene)(PEDOT-OH) nanospheres self-assembled using physical blowing method, which continually used a syringe, were successfully formed through aqueous solution polymerization under the oxidative initiators. The effect of blowing on the morphological properties of PEDOT-OH was precisely evaluated based on the different amount of initiator. The concentration of ammonium persulfate might be a driving force in the self-assembly process to create the PEDOT-OH nanospheres. The electrical and electrochemical properties of the resulting nanospheres were also characterized using four-point probe and cyclic voltammetry.

Efficacy of Periprostatic Anesthesia according to Lidocaine Dose during Transrectal Ultrasound-Guided Biopsy of the Prostate.

PURPOSE: The aim of this study was to evaluate the efficacy of periprostatic lidocaine injection according to lidocaine dose during transrectal ultrasound-guided prostate biopsy. MATERIALS AND METHODS: The subjects of this study were 92 patients who had undergone transrectal ultrasound-guided 12-core biopsy of the prostate. The patients were randomly assigned to three groups: group 1 (n=31, no lidocaine injection), group 2 (n=30, periprostatic injection of 10 ml 1% lidocaine), and group 3 (n=31, periprostatic injection of 20 ml 1% lidocaine). The patients were assessed for pain by use of a 10-point visual analogue scale (VAS) and for other complications after the procedure. RESULTS: The mean VAS scores of groups 1 through 3 were 0.93±0.89, 1.32±1.37, and 1.13±1.10, respectively. There were no statistically significant differences between the three groups. However, the mean VAS score of the biopsy pain was 5.0±1.48, 3.93±1.94, and 3.60±2.15, in the same groups, respectively, with statistically significant differences between group 1 and the other groups. Patients in groups 2 and 3 reported significantly less biopsy pain than did group 1 patients (p=0.004, 0.021), with no statistically significant difference in VAS score between groups 2 and 3 (p=0.533). With respect to post-biopsy complications, there were no significant differences in the incidence of hematuria, hematospermia, rectal bleeding, or infection among the three groups. CONCLUSIONS: Periprostatic injection of local anesthesia with lidocaine was associated with significantly less pain than in the absence of anesthesia. Furthermore, a 20-ml dose of lidocaine produced no better pain control than did a 10-ml lidocaine dose for prostate biopsy.

Cystic dysplasia of the rete testis accompanying an inguinal hernia: a 63-year-old man.

Cystic dysplasia of the rete testis (CDT) is a very rare congenital benign testicular tumor that is often associated with ipsilateral genitourinary anomalies. It is usually found in the pediatric population and must be differentially diagnosed from a malignant lesion. Here we report the case of a 63-year-old man with a left inguinal hernia who visited our urologic outpatient clinic. Scrotal ultrasonography showed a left direct inguinal hernia in the inguinal area and a well-circumscribed cystic lesion containing multiple minute cysts with echogenic foci occupying almost one-third of the left testicular parenchyma. Testicular tumor markers were within the normal range and a computed tomography scan of the abdomen showed no genitourinary abnormalities. We presumed that the left testicular lesion was malignant, and the patient underwent radical orchiectomy. However, the pathologic examination revealed a CDT. Here we present this case of a 63-year-old man with an inguinal hernia accompanied by multiple cystic lesions on the left testis.