One-step vapor-phase synthesis of transparent high refractive index sulfur-containing polymers

Inverse Vulcanization of Activated Norbornenyl Esters-A Versatile Platform for Functional Sulfur Polymers

Elemental sulfur has shown to be a promising alternative feedstock for development of novel polymeric materials with high sulfur content. However, the utilization of inverse vulcanized polymers is restricted by the limitation of functional comonomers suitable for an inverse vulcanization. Control over properties and structure of inverse vulcanized polymers still poses a challenge to current research due to the dynamic nature of sulfur-sulfur bonds and high temperature of inverse vulcanization reactions. In here, we report for the first time the inverse vulcanization of norbornenyl pentafluorophenyl ester (NB-PFPE), allowing for post-modification of inverse vulcanized polymers via amidation of reactive PFP esters to yield high sulfur content polymers under mild conditions. Amidation of the precursor material with three functional primary amines (α-amino-ω-methoxy polyethylene glycol, aminopropyl trimethoxy silane, allylamine) was investigated. The resulting materials were applicable as sulfur containing poly(ethylene glycol) nanoparticles in aqueous environment. Cross-linked mercury adsorbents, sulfur surface coatings, and high-sulfur content networks with predictable thermal properties were achievable using aminopropyl trimethoxy silane and allylamine for post-polymerization modification, respectively. With the broad range of different amines available and applicable for post-polymerization modification, the versatility of poly(sulfur-random-NB-PFPE) as a platform precursor polymer for novel specialized sulfur containing materials was showcased.

Size Control and Antioxidant Properties of Sulfur-Rich Polymer Colloids from Interfacial Polymerization

High sulfur content polymeric materials, known for their intriguing properties such as high refractive indices and high electrochemical capacities, have garnered significant interest in recent years for their applications in optics, antifouling surfaces, triboelectrics, and electrochemistry. Despite the high interest, most high sulfur-content polymers reported to date are either bulk materials or thin films, and there is a general lack of research into sulfur-rich polymer colloids. Water-dispersed, sulfur-rich particles are anticipated to broaden the range of applications for sulfur-containing materials. In this study, the preparation and size control parameters are presented of an aqueous dispersion of sulfur-rich polymers with the sulfur content of dispersed particles exceeding 75 wt%. Employing polymeric stabilizers with varying hydrophilic-lipophilic balance (HLB), along with changing the rank of inorganic polysulfides, allow for the control of particle size in the range of 360 nm - 1.8 µm. The sulfur-rich colloid demonstrates antioxidant properties in water, demonstrating the potential for the use of sulfur-rich polymeric materials readily removable, heterogeneous radical scavengers.

Structural evolution during inverse vulcanization

Inverse vulcanization exploits S8 to synthesize polysulfides. However, evolution of products and its mechanism during inverse vulcanization remains elusive. Herein, inverse vulcanization curves are obtained to describe the inverse vulcanization process in terms of three stages: induction, curing and over-cure. The typical curves exhibit a moduli increment before declining or plateauing, reflecting the process of polysulfide network formation and loosing depending on monomers. For aromatic alkenes, in the over-cure, the crosslinked polysulfide evolves significantly into a sparse network with accelerated relaxation, due to the degradation of alkenyl moieties into thiocarbonyls. The inverse vulcanization product of olefins degrades slowly with fluctuated relaxation time and modulus because of the generation of thiophene moieties, while the inverse vulcanization curve of dicyclopentadiene has a plateau following curing stage. Confirmed by calculations, the mechanisms reveal the alkenyl groups react spontaneously into thiocarbonyls or thiophenes via similar sulfur-substituted alkenyl intermediates but with different energy barriers.

Easy Synthetic Access to High-Melting Sulfurated Copolymers and their Self-Assembling Diblock Copolymers from Phenylisothiocyanate and Oxetane

Although sulfurated polymers promise unique properties, their controlled synthesis, particularly when it comes to complex and functional architectures, remains challenging. Here, we show that the copolymerization of oxetane and phenyl isothiocyanate selectively yields polythioimidocarbonates as a new class of sulfur containing polymers, with narrow molecular weight distributions (Mn=5-80 kg/mol with Đ≤1.2; Mn,max=124 kg/mol) and high melting points of up to 181 °C. The method tolerates different substituent patterns on both the oxetane and the isothiocyanate. Self-nucleation experiments reveal that π-stacking of phenyl substituents, the presence of unsubstituted polymer backbones, and the kinetically controlled linkage selectivity are key factors in maximising melting points. The increased tolerance to macro-chain transfer agents and the controlled propagation allows the synthesis of double crystalline and amphiphilic diblock copolymers, which can be assembled into micellar- and worm-like structures with amorphous cores in water. In contrast, crystallization driven self-assembly in ethanol gives cylindrical micelles or platelets.

Multicomponent Polymerizations of Elemental Sulfur, CH2Cl2, and Aromatic Amines toward Chemically Recyclable Functional Aromatic Polythioureas

The exploration of new polymer materials required the development of efficient, economic, robust, and scalable synthetic routes, taking energy consumption, environmental benefit, and sustainability into overall consideration. Herein, through retro-polymerization analysis of functional aromatic polythioureas, a multicomponent reaction of elemental sulfur, CH2Cl2, and aromatic amines was designed with the assistance of fluoride, and efficient, economic, and robust multicomponent polymerizations (MCPs) of these three abundantly available cheap monomers, elemental sulfur, CH2Cl2, and aromatic diamines, were developed to realize scalable conversion directly from sulfur to a series of functional aromatic polythioureas with high molecular weights (Mn up to 50,800 g/mol) in excellent yields (up to 98%). The synergistic cooperation of the strong and selective coordination of thiourea with gold ions and the redox property of aromatic polythiourea enable in situ reduction of Au3+ to elemental gold under a normal bench condition. Furthermore, the functional aromatic polythiourea could be chemically recycled through aminolysis with NH3·H2O to afford a diamine monomer in 83% isolated yield. The development of elemental sulfur-based MCP has brought the opportunity to access cost-effective and sustainable sulfur-containing functional polymer materials, which is anticipated to provide a solution for the utilization of sulfur waste and making profitable polymer materials.

Converting inorganic sulfur into degradable thermoplastics and adhesives by copolymerization with cyclic disulfides

Converting elementary sulfur into sulfur-rich polymers provides a sustainable strategy to replace fossil-fuel-based plastics. However, the low ring strain of eight-membered rings, i.e., S8 monomers, compromises their ring-opening polymerization (ROP) due to lack of an enthalpic driving force and as a consequence, poly(sulfur) is inherently unstable. Here we report that copolymerization with cyclic disulfides, e.g., 1,2-dithiolanes, can enable a simple and energy-saving way to convert elementary sulfur into sulfur-rich thermoplastics. The key strategy is to combine two types of ROP-both mediated by disulfide bond exchange-to tackle the thermodynamic instability of poly(sulfur). Meanwhile, the readily modifiable sidechain of the cyclic disulfides provides chemical space to engineer the mechanical properties and dynamic functions over a large range, e.g., self-repairing ability and degradability. Thus, this simple and robust system is expected to be a starting point for the organic transformation of inorganic sulfur toward sulfur-rich functional and green plastics.

Closed-loop recycling of sulfur-rich polymers with tunable properties spanning thermoplastics, elastomers, and vitrimers

The development of closed-loop recycling polymers that exhibit excellent performance is of great significance. Sulfur-rich polymers possessing excellent optical, thermal, and mechanical properties are promising candidates for chemical recycling but lack efficient synthetic strategies for achieving diverse structures. Herein, we report a universal synthetic strategy for producing polytrithiocarbonates, a class of sulfur-rich polymers, via the polycondensation of dithiols and dimethyl trithiocarbonate. This strategy has excellent compatibility with a wide range of monomers, including aliphatic, heteroatomic, and aromatic dithiols enabling the synthesis of polytrithiocarbonates with diverse structures. The present synthesis strategy offers a versatile platform for the construction of thermoplastics, elastomers, and vitrimers. Notably, these polytrithiocarbonates can be easily depolymerized via solvolysis into the corresponding monomers, which can be repolymerized to virgin polymers without changing the material properties.

Ultrathin organosiloxane membrane for precision organic solvent nanofiltration

Promising advances in membrane technology can lead to energy-saving and eco-friendly solutions in industrial sectors. This work demonstrates a highly selective membrane with ultrathin and highly interconnected organosiloxane polymer nanolayers by initiated chemical vapor deposition to effectively separate solutes within the molecular weight range of 150-300 g mol-1. We optimize the poly(1,3,5,7-tetravinyl-1,3,5,7-tetramethylcyclotetrasiloxane) membrane by adjusting both the thickness of the selective layer and the pore sizes of its support membranes. Notably, the 29 nm selective layer imparts a uniformly narrow molecular sieving property, providing a record-high solute-solute selectivity of 39.88 for different-sized solutes. Furthermore, a solute-solute selectivity of 11.04 was demonstrated using the real-world active pharmaceutical ingredient mixture of Acyclovir and Valacyclovir, key components for Herpes virus treatment, despite their molecular weight difference of less than 100 g mol-1. The highly interconnected membrane is expected to meet rigorous requirements for high-standard active pharmaceutical ingredient separation.

Step-growth Polymerization of Aziridines with Elemental Sulfur: Easy Access to Linear Polysulfides and Their Use as Recyclable Adhesives

The bulk radical polymerization of bis(aziridine) with molten elemental sulfur resulted in brittle, cross-linked polymers. However, when the bis(aziridine) was treated with elemental sulfur in the presence of an organobase, the ring-opening reaction of aziridine with oligosulfide anions occurred, leading to the formation of linear polymers by step-growth polymerization. These newly synthesized polymers possess repeating units containing a sulfonamide or amide functional moiety and oligosulfide bonds with an average sulfur segment of about two. A small molecular model reaction confirmed the nucleophilic addition reaction of elemental sulfur to aziridine. It was verified that S-S dynamic bond exchange takes place in the presence of an organic base within the linear chains. The mixture of the synthesized polysulfides with pyridine exhibits exceptional adhesive properties when applied to steel, and aluminum substrates. Notably, these prepared adhesives displayed good reusability due to the dynamic S-S exchange and complete recyclability due to their solution processability. This elemental sulfur-involved polymerization approach represents an innovative method for the synthesis of advanced sulfur-containing polymers, demonstrating the potential for various applications in adhesives and beyond.

Recent Progress in Sulfur-Containing High Refractive Index Polymers for Optical Applications

The development in the field of high refractive index materials is a crucial factor for the advancement of optical devices with advanced features such as image sensors, optical data storage, antireflective coatings, light-emitting diodes, and nanoimprinting. Sulfur plays an important role in high refractive index applications owing to its high molar refraction compared to carbon. Sulfur exists in multiple oxidation states and can exhibit various stable functional groups. Over the last few decades, sulfur-containing polymers have attracted much attention owing to their wide array of applications governed by the functional group of sulfur present in the polymer repeat unit. The interplay of refractive index and various other polymer properties contributes to successfully implementing a specific polymer material in optical applications. The focus on developing optoelectronic devices induced an ever-increasing need to integrate different functional materials to achieve the devices' full potential. Several devices that see the potential use of sulfur in high refractive index materials are reviewed in the study. Like sulfur, selenium also exhibits high molar refraction and unique chemical properties, making it an essential field of study. This review covers the research and development in the field of sulfur and selenium in different forms of functionality, focusing on the chemistry of bonding and the optical properties of the polymers containing the heteroatoms mentioned above. The strategy and rationale behind incorporating heteroatoms in a polymer matrix to produce high-refractive-index materials are also described in the present review.

Light Management of Metal Halide Scintillators for High-Resolution X-Ray Imaging

The ever-growing need to inspect matter with hyperfine structures requires a revolution in current scintillation detectors, and the innovation of scintillators is revived with luminescent metal halides entering the scene. Notably, for any scintillator, two fundamental issues arise: Which kind of material is suitable and in what form should the material exist? The answer to the former question involves the sequence of certain atoms into specific crystal structures that facilitate the conversion of X-ray into light, whereas the answer to the latter involves assembling these crystallites into particular material forms that can guide light propagation toward its corresponding pixel detector. Despite their equal importance, efforts are overwhelmingly devoted to improving the X-ray-to-light conversion, while the material-form-associated light propagation, which determines the optical signal collected for X-ray imaging, is largely overlooked. This perspective critically correlates the reported spatial resolution with the light-propagation behavior in each form of metal halides, combing the designing rules for their future development.

Base-Assisted Polymerizations of Elemental Sulfur and Alkynones for Temperature-Controlled Synthesis of Polythiophenes or Poly(1,4-dithiin)s

With the increasing demand for functional polythiophenes in extensive applications such as organic solar cells, electronic skins, thermoelectric materials, and field effect transistors, efficient and economic synthetic approaches for polythiophenes are urgently required. In this work, KOH-assisted polymerizations of elemental sulfur and alkynones were developed to directly afford polythiophenes with various backbones, regioselective structures, and high molecular weights (Mns up to 20700 g/mol) in high yields (up to 97%) at 80 °C in 30 min. When the same polymerization was conducted at room temperature, stable and unique poly(1,4-dithiin)s (Mns up to 21800 g/mol) could be rapidly obtained in high yields (up to 87%) in 10 min. The temperature-controlled KOH-assisted polymerizations of sulfur and alkynones possessed high efficiency, mild conditions, and simple operation, which had provided an economic, efficient, and convenient approach for the direct conversion from elemental sulfur to functional polythiophenes and poly(1,4-dithiin)s with the in situ constructed aromatic or nonaromatic heterocycles embedded in the polymer backbones, demonstrating great synthetic simplicity, high efficiency, good selectivity, and robustness. It is anticipated to accelerate the development of semiconducting polymer materials and their applications.

Molecular Structure and Properties of Sulfur-Containing High Refractive Index Polymer Optical Materials

High refractive index polymers (HRIPs) are widely used in lenses, waveguide, antireflective layer and encapsulators, especially the advanced fields of augmented/virtual reality (AR / VR) holographic technology and photoresist for chip manufacturing. In order to meet the needs of different applications, the development of HRIPs focuses not only on the increase in refractive index but also on the balance of other properties. Sulfur-containing high refractive index polymers have received extensive attention from researchers due to their excellent properties. In recent years, not only ultrahigh refractive index sulfur-containing polymers have been continuously developed, but also low dispersion, low birefringence, high transparency, good mechanical properties, and machinability have been studied. The design of HRIPs is generally based on formulas and existing experience. In fact, molecular structure and properties are closely related. Mastering the structure-property relationship helps researchers to develop high refractive index polymer materials with balanced properties. This review briefly introduces the preparation methods of sulfur-containing high refractive index polymers, and summarizes the structure-property relationship between the sulfur-containing molecular structure and optical properties, mechanical properties, thermal properties, etc. Finally, the important role of synergistic effect in the synthesis of HRIPs and the prospect of future research on HRIPs are proposed.

Precise construction of weather-sensitive poly(ester-alt-thioesters) from phthalic thioanhydride and oxetane

We report the selective ring opening copolymerisation (ROCOP) of oxetane and phthalic thioanhydride by a heterobimetallic Cr(III)K catalyst precisely yielding semi-crystalline alternating poly(ester-alt-thioesters) which show improved degradability due to the thioester links in the polymer backbone.

Fabrication of UV-Curable Polysiloxane Coating with Tunable Refractive Index Based on Controllable Hydrolysis

In order to improve laser transmission efficiency at 1053 nm and 527 nm, a potassium deuterium phosphate (DKDP) crystal (a key component of high-power laser systems) needs a bi-layer antireflection coating system on its incident surface. UV-curable polysiloxane coatings with a refractive index varying from 1.500 to 1.485 were prepared through the polycondensation of a methacryloxy propyl trimethoxylsilane (MPS) monomer with a controllable degree of hydrolysis. Additionally, the influence rule of the coating structure on the refractive index was intensively studied, and the primary factors that dominate the hydrolysis process were discussed. Further refractive index adjustment was achieved using only a small amount of dopant based on the polysiloxane coating with refractive index of 1.485, allowing for high antireflection of the bi-layer coating system at desired wavelengths to be achieved. In addition, high laser damage resistance and remarkable mechanical properties of the coating were simultaneously realized through the incorporation of a minor quantity of dopants, which benefited from the successful modulation of the intrinsic refractive index of the polysiloxane coating.

All-organic polymeric materials with high refractive index and excellent transparency

High refractive index polymers (HRIPs) have drawn attention for their optoelectronic applications and HRIPs with excellent transparency and facile preparation are highly demanded. Herein, sulfur-containing all organic HRIPs with refractive indices up to 1.8433 at 589 nm and excellent optical transparency even in one hundred micrometre scale in the visual and RI region as well as high weight-average molecular weights (up to 44500) are prepared by our developed organobase catalyzed polymerization of bromoalkynes and dithiophenols in yields up to 92%. Notably, the fabricated optical transmission waveguides using the resultant HRIP with the highest refractive index display a reduced propagation loss compared with that generated by the commercial material of SU-8. In addition, the tetraphenylethylene containing polymer not only exhibits a reduced propagation loss, but also is used to examine the uniformity and continuity of optical waveguides with naked eyes because of its aggregation-induced emission feature.

High Refractive Index Polymer Thin Films by Charge-Transfer Complexation

High refractive index polymers are essential in next-generation flexible optical and optoelectronic devices. This paper describes a simple synthetic method to prepare polymeric optical coatings possessing high refractive indexes. Poly(4-vinylpyridine) (P4VP) thin films prepared using initiated chemical vapor deposition are exposed to highly polarizable halogen molecules to form stable charge-transfer complexes: P4VP-IX (X = I, Br, and Cl). Fourier transform infrared spectroscopy was used to confirm the formation of charge-transfer complexes. Characterized by spectroscopic ellipsometry, the maximum refractive index of 2.08 at 587.6 nm is obtained for P4VP-I₂. For P4VP-IBr and P4VP-ICl, the maximum refractive indexes are 1.849 and 1.774, respectively. By controlling the concentration of charge-transfer complexes, either through the halogen incorporation step or polymer composition through copolymerization with ethylene glycol dimethacrylate, the refractive indexes of the polymer thin films can be precisely controlled. The feasibility of P4VP-IX materials as optical coatings is also explored. The refractive index and thickness uniformity of a P4VP-I₂ film over a 10 mm diameter circular area were characterized, showing standard deviations of 0.0769 and 1.91%, respectively.

Advances in the One-Step Approach of Polymeric Materials Using Enzymatic Techniques

The formulation in which biochemical enzymes are administered in polymer science plays a key role in retaining their catalytic activity. The one-step synthesis of polymers with highly sequence-controlled enzymes is a strategy employed to provide enzymes with higher catalytic activity and thermostability in material sustainability. Enzyme-catalyzed chain growth polymerization reactions using activated monomers, protein-polymer complexation techniques, covalent and non-covalent interaction, and electrostatic interactions can provide means to develop formulations that maintain the stability of the enzyme during complex material processes. Multifarious applications of catalytic enzymes are usually attributed to their efficiency, pH, and temperature, thus, progressing with a critical structure-controlled synthesis of polymer materials. Due to the obvious economics of manufacturing and environmental sustainability, the green synthesis of enzyme-catalyzed materials has attracted significant interest. Several enzymes from microorganisms and plants via enzyme-mediated material synthesis have provided a viable alternative for the appropriate synthesis of polymers, effectively utilizing the one-step approach. This review analyzes more and deeper strategies and material technologies widely used in multi-enzyme cascade platforms for engineering polymer materials, as well as their potential industrial applications, to provide an update on current trends and gaps in the one-step synthesis of materials using catalytic enzymes.

Determining the Local Refractive Index of Single Particles by Optical Imaging Technique

The refractive index points to the interplay between light and objects, which is rarely studied down to micronano scale. Herein, we demonstrated a conventional bright-field imaging technique to determine the local refractive index of single particles combined with a series of refractive index standard solutions. This intrinsic optical property is independent with the particle size and surface roughness with a single chemical component. Furthermore, we accurately tuned refractive index of homemade core-shell nanoparticles by adjusting the ratio of core-to-shell geometry. This simple and effective strategy reveals extensive applications in exploring, designing and optimizing the physical and optical characterizations of composite photonic crystals with high precision. It also indicates potentials in the field of reflective displays, optical identification, and encryption.

Transcending the Trade-off in Refractive Index and Abbe Number for Highly Refractive Polymers: Synergistic Effect of Polarizable Skeletons and Robust Hydrogen Bonds

High-refractive-index polymers (HRIPs) are attractive materials for the development of optical devices with high performances. However, because practical components and structures for HRIPs are limited from the viewpoint of synthetic techniques, it has proved difficult using traditional strategies to enhance the refractive index (RI) of HRIPs to more than a certain degree (over 1.8) while maintaining their visible transparency. Here, we found that poly(phenylene sulfide) (PPS) derivatives featuring both methylthio and hydroxy groups can simultaneously exhibit balanced properties of an ultrahigh RI of n _D = 1.85 and Abbe number of ν_D = 20 owing to the synergistic effect of high molar refraction and dense intermolecular hydrogen bonds (H-bonds). This brand new strategy is anticipated to contribute to the development of HRIPs displaying ultrahigh RI with adequate Abbe numbers beyond the empirical n _D-ν_D threshold, which has not been achieved to date.

Mechanochemical synthesis of inverse vulcanized polymers

Inverse vulcanization, a sustainable platform, can transform sulfur, an industrial by-product, into polymers with broad promising applications such as heavy metal capture, electrochemistry and antimicrobials. However, the process usually requires high temperatures (≥159 °C), and the crosslinkers needed to stabilize the sulfur are therefore limited to high-boiling-point monomers only. Here, we report an alternative route for inverse vulcanization—mechanochemical synthesis, with advantages of mild conditions (room temperature), short reaction time (3 h), high atom economy, less H₂S, and broader monomer range. Successful generation of polymers using crosslinkers ranging from aromatic, aliphatic to volatile, including renewable monomers, demonstrates this method is powerful and versatile. Compared with thermal synthesis, the mechanochemically synthesized products show enhanced mercury capture. The resulting polymers show thermal and light induced recycling. The speed, ease, versatility, safety, and green nature of this process offers a more potential future for inverse vulcanization, and enables further unexpected discoveries.

Inverse vulcanization is a process that enables to convert sulfur, a by-product of the petroleum industry, into polymers. Here the authors report a synthetic method of inverse vulcanization via mechanochemical synthesis; compared to thermal routes, a broader range of monomers can be used, and the protocol yields materials with enhanced mercury capture capacity.

High Refractive Index Diphenyl Sulfide Photopolymers for Solar Cell Antireflection Coatings

The anti-reflection film can effectively reduce the surface reflectivity of solar photovoltaics, increase the transmittance of light, and improve the photoelectric conversion efficiency. The high refractive index coating is an important part of the anti-reflection film. However, the traditional metal oxide coating has poor stability and complicated processes. To address this issue, we prepared two organic high refractive index (HRI) photopolymers by modifying epoxy acrylic acid with 4,4′-thiodibenzenethiol, which can be surface patterned by nanoimprinting to prepare antireflection coatings. As a result, two modified photopolymers with high refractive index (n > 1.63), high optical transmittance (T > 95%), and thermal stability (Tg > 100 °C) are obtained after curing. In particular, the diphenyl sulfide photopolymer modified by ethyl isocyanate acrylate has a refractive index up to 1.667 cured by UV light. Our work confirms that the organic HRI photopolymer can be obtained by introducing high molar refractive index groups, with potential to be applied as a PV cell power conversion efficiency material.

Controlled Disassembly of Elemental Sulfur: An Approach to the Precise Synthesis of Polydisulfides

The usage of elemental sulfur (S₈ ) for constructing sulfur-containing polymers is of great significance in terms of sulfur resource utilization or fabrication of high-performance polymers. Currently, the random disassembly of S₈ hinders its direct use in the precise synthesis of sulfur-containing polymers. Herein, we provide an effective strategy for controlling the dismantlement of S₈ to synthesize polydisulfides, a promising category of dynamic bonds containing polymers. In this strategy, the completely alternating copolymerization of one sulfur atom, which is orderly derived from S₈ , with episulfides is achieved with MTBD (7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene) as catalyst and [PPN]SbF₆ ([PPN]⁺ is bis(triphenylphosphine)iminium) as cocatalyst. Delightedly, the living- polymerization feature, and the good monomer compatibility allows for the access to diverse polydisulfides. Furthermore, the density functional theory (DFT) was employed to elaborate the copolymerization process.

Interfacial AIE for Orthogonal Integration of Holographic and Fluorescent Dual-Thermosensitive Images

Orthogonal integration of thermosensitive images is of vital significance for advanced anticounterfeiting, which however remains formidably challenging due to the trade-off that facile thermoresponse needs easy molecular motion while robust imaging requires molecular restriction. Herein, a viable approach is demonstrated to tackle the challenge by in situ fixing a predesigned aggregation induced emission luminogen (AIEgen) at the polymer/liquid crystal (LC) interface via precisely controlled interfacial engineering, in which the AIEgen is enriched in LC phases during polymerization induced phase separation and subsequently driven to the interface by the interfacial thiol-ene click reaction. Crosstalk-free integration of holographic and fluorescent dual-thermosensitive images with high sensitivity, high contrast ratio, and robust performance is successfully realized in a single unit, attributed to the simultaneously LC-facilitated AIEgen molecular motion and polymer-restricted AIEgen diffusion at the interface. The exciting characteristics of these orthogonally integrated dual images will enable them to prevent illegal replication and thus are expected to be promising for high-security-level anticounterfeiting applications.

Tributylphosphine-catalyzed aziridine-based cycloaddition polymerization toward thiacyclic polymers

Cycloaddition polymerization of bis(N-sulfonyl aziridine)s with diisocyanates in the presence of tributylphosphine allows the facile synthesis of poly(thiazolidin-2-imine)s.

A bio-based, robust and recyclable thermoset polyester elastomer by using an inverse vulcanised polysulfide as a crosslinker

We report the synthesis of a bio-based, robust and recyclable thermoset polyester elastomer by using an inverse vulcanised sulfur-polymer (SP) as a crosslinker for the bio-based polyester elastomer (BPE).

Sulfur-containing polymers derived from SO2: synthesis, properties, and applications

Sulfur-containing polymers enjoy the merits of excellent optical performance, degradation, chemical recyclability, and adhesive abilities toward metal ions. Recently, increasing attentions in both academic and industrial circles have been paid...

Transparent, Ultrahigh-Refractive Index Polymer Film (n ∼1.97) with Minimal Birefringence (Δn <0.0010)

High refractive index (RI) thin films are of critical importance for advanced optical devices, and the high refractive index polymers (HRIPs) constitute an interesting class of materials for high RI thin films due to low cost, good processability, light weight, and high flexibility. However, HRIPs have yet to realize their full potential in high RI thin film applications due to their relatively low RI, strong absorption in the blue light region, and limited film formation methods such as rapid vitrification. Herein, we report a development of a new HRIP thin film generated through a one-step vapor-phase process, termed sulfur chemical vapor deposition (sCVD), using elemental sulfur and divinyl benzene. The developed poly(sulfur-co-divinyl benzene) (pSDVB-sCVD) film exhibited RI (measured at 632.8 nm) exceeding 1.97, one of the highest RIs among polymers without metallic elements reported to date. Because the sCVD utilized vaporized sulfur with a unique sulfur-cracking step, formation of long polysulfide chains was suppressed efficiently, while high sulfur content as high as 85 wt % could be achieved with no apparent phase separation. Unlike most of inorganic high RI materials, pSDVB-sCVD was highly transparent in the entire visible range and showed extremely low birefringence of 10 × 10^-4. The HRIP thin film with unprecedentedly high RI, together with outstanding transparency and low birefringence, will serve as a key component in a wide range of high-end optical device applications.

Polymerizations with Elemental Sulfur: From Petroleum Refining to Polymeric Materials

The production of elemental sulfur from petroleum refining has created a technological opportunity to increase the valorization of elemental sulfur by the synthesis of high-performance sulfur-based plastics with improved optical, electrochemical, and mechanical properties aimed at applications in thermal imaging, energy storage, self-healable materials, and separation science. In this Perspective, we discuss efforts in the past decade that have revived this area of organosulfur and polymer chemistry to afford a new class of high-sulfur-content polymers prepared from the polymerization of liquid sulfur with unsaturated monomers, termed inverse vulcanization.

Enhancing the Refractive Index of Polymers with a Plant-Based Pigment

Polymers are essential components of many nanostructured materials. However, the refractive indices of common polymers fall in a relatively narrow range between 1.4 and 1.6. Here, it is demonstrated that loading commercially-available polymers with large concentrations of a plant-based pigment can effectively enhance their refractive index. For polystyrene (PS) loaded with 67 w/w% β-carotene (BC), a peak value of 2.2 near the absorption edge at 531 nm is achieved, while maintaining values above 1.75 across longer wavelengths of the visible spectrum. Despite high pigment loadings, this blend maintains the thermoforming ability of PS, and BC remains molecularly dispersed. Similar results are demonstrated for the plant-derived polymer ethyl cellulose (EC). Since the refractive index enhancement is intimately connected to the introduction of strong absorption, it is best suited to applications where light travels short distances through the material, such as reflectors and nanophotonic systems. Enhanced reflectance from films is experimentally demonstrated, as large as sevenfold for EC at selected wavelengths. Theoretical calculations highlight that this simple strategy can significantly increase light scattering by nanoparticles and enhance the performance of Bragg reflectors.

Precisely Alternating Copolymerization of Episulfides and Isothiocyanates: A Practical Route to Construct Sulfur-Rich Polymers

The development of a controlled and reliable method to construct well-defined sulfur-containing polymers has sparked great interest in polymer science. Herein, we present the trial on the copolymerization of isothiocyanates with episulfides in the presence of organic onium salts, which provides direct access to a class of sulfur-rich polymers. This methodology has combined advantages of simple operation, no metals, mild conditions (25-100 °C), controlled polymerization performance (M_n > 10⁵ g mol^-1, Đ < 1.3), and high reactivity (turnover frequency over 1000 h^-1). The metal-free feature and versatility of the easily accessible monomers, along with fine adjustment of the final properties enable this strategy to be a feasible approach to produce sulfur-rich polymers (16 examples).

Unprecedentedly high active organocatalysts for the copolymerization of carbonyl sulfide and propylene oxide: steric hindrance effect of tertiary amines

The TEB/DMCHA pair shows exceedingly high turnover frequency of 69 800 h−1 for organocatalytic COS/PO copolymerization at 60 °C under solvent-free conditions.

Randomly Distributed Sulfur Atoms in the Main Chains of CO2 -Based Polycarbonates: Enhanced Optical Properties

Polymeric materials possessing both high refractive indices and high Abbe numbers are much in demand for the development of advanced optical devices. However, the synthesis of such functional materials is a challenge because of the trade-off between these two properties. Herein, a synthetic strategy is presented for enhancing the optical properties of CO₂ -based polycarbonates by modifying the polymer's topological structure. Terpolymers with thiocarbonate and carbonate units randomly distributed in the polymers' main chain were synthesized via the terpolymerization of cyclohexene oxide with a mixture of CO₂ and COS in the presence of metal catalysts, most notably a dinuclear aluminum complex. DFT calculations were employed to explain why different structural sequence were obtained with distinct bimetallic catalysts. Varying the CO₂ pressure made it possible to obtain terpolymers with tunable carbonate linkages in the polymer chain. More importantly, optical property studies revealed that terpolymers with comparable thiocarbonate and carbonate units exhibited a refractive index of 1.501 with an enhanced Abbe number as high as 48.6, much higher than the corresponding polycarbonates or polythiocarbonates. Additionally, all terpolymers containing varying thiocarbonate content displayed good thermal properties with T_g >109 °C and T_d >260 °C, suggesting little loss in the thermal stability compared to the polycarbonate. Hence, modification of the topological structure of the polycarbonate is an efficient method of obtaining polymeric materials with enhanced optical properties without compromising thermal performance.