Solid Poly Research Articles

SnOct2-catalyzed and alcohol-initiated ROPs of L-lactide – About the influence of initiators on chemical reactions in the melt and the solid state

SnOct2 (Sn(II) 2-ethylhexanoate) catalyzed ROPs of L-lactide were performed in bulk with eight different alcohols as initiators. The time was varied between 1 h and 24 h for all initiators. For two initiators the temperature was also lowered to 115 °C. Even-numbered chains were predominantly formed in all polymerizations at short times, but the rate of transesterification (e.g. even/odd equilibration) and the molecular weight distribution were found to depend significantly on the nature of the initiator. Observed transesterification reactions also continued in solid poly(L-lactide), and with the most active initiator, almost total equilibration was achieved even at 130 °C. This means that all chains including those of the crystallites were involved in transesterification reactions proceeding across the flat surfaces of the crystallites. The more or less equilibrated crystalline polylactides were characterized by DSC and SAXS measurements with regard to their melting temperature (Tm), crystallinity and crystal thickness.

Injection molding for manufacturing of solid poly(l-lactide-co-glycolide) microneedles

A solid microneedle array can be used for “poke and flow” transdermal delivery of a drug, which involves the infusion or diffusion of a drug through pores in the skin that were created by the microneedle array. In this paper, solid microneedle arrays were created out of the polymer RESOMER LG 855 S—poly(l-lactide-co-glycolide) using injection molding. Scanning electron microscopy revealed that the microneedle in the injection-molded four-by-one microneedle array closely matched the dimensions that were used for injection molding. X-ray photoelectron spectroscopy revealed that the carbon bonding in the microneedle material matched that expected for poly(l-lactide-co-glycolide). The reduced elastic modulus of the microneedle material, 6.04 ± 0.17 GPa, was noted to be appropriate for skin penetration applications. The microneedle array was used for the delivery of the model drug methyl blue to surgically discarded human underarm skin. These results suggest that injection molding of RESOMER LG 855 S—poly(l-lactide-co-glycolide) may be an appropriate approach for large-scale manufacturing of solid microneedles.

Mechanical, thermal, and microstructural analyses of thermoplastic poly(2-methoxyethyl acrylate)-based polyurethane by RAFT and polyaddition

A thermoplastic solid poly(2-methoxyethyl acrylate)(PMEA)-based polyurethane(PU) with excellent thermo-mechanical properties and antithrombogenicity was obtained by increasing the molecular weight of PMEA-based PU to ∼80 k.

Liquid-Free All-Solid-State Zinc Batteries and Encapsulation-Free Flexible Batteries Enabled by In Situ Constructed Polymer Electrolyte.

Zn batteries are usually considered as safe aqueous systems that are promising for flexible batteries. On the other hand, any liquids, including water, being encapsulated in a deformable battery may result in problems. Developing completely liquid-free all-solid-state Zn batteries needs high-quality solid-state electrolytes (SSEs). Herein, we demonstrate in situ polymerized amorphous solid poly(1,3-dioxolane) electrolytes, which show high Zn ion conductivity of 19.6 mS cm-1 at room temperature, low interfacial impedance, highly reversible Zn plating/stripping over 1800 h cycles, uniform and dendrite-free Zn deposition, and non-dry properties. The in-plane interdigital-structure device with the electrolyte completely exposed to the open atmosphere can be operated stably for over 30 days almost without weight loss or electrochemical performance decay. Furthermore, the sandwich-structure device can normally operate over 40 min under exposure to fire. Meanwhile, the interfacial impedance and the capacity using in situ-formed solid polymer electrolytes (SPEs) remain almost unchanged after various bending tests, a key criterion for flexible/wearable devices. Our study demonstrates an approach for SSEs that fulfill the requirement of no liquid and mechanical robustness for practical solid-state Zn batteries.

Liquid‐Free All‐Solid‐State Zinc Batteries and Encapsulation‐Free Flexible Batteries Enabled by In Situ Constructed Polymer Electrolyte

AbstractZn batteries are usually considered as safe aqueous systems that are promising for flexible batteries. On the other hand, any liquids, including water, being encapsulated in a deformable battery may result in problems. Developing completely liquid‐free all‐solid‐state Zn batteries needs high‐quality solid‐state electrolytes (SSEs). Herein, we demonstrate in situ polymerized amorphous solid poly(1,3‐dioxolane) electrolytes, which show high Zn ion conductivity of 19.6 mS cm−1 at room temperature, low interfacial impedance, highly reversible Zn plating/stripping over 1800 h cycles, uniform and dendrite‐free Zn deposition, and non‐dry properties. The in‐plane interdigital‐structure device with the electrolyte completely exposed to the open atmosphere can be operated stably for over 30 days almost without weight loss or electrochemical performance decay. Furthermore, the sandwich‐structure device can normally operate over 40 min under exposure to fire. Meanwhile, the interfacial impedance and the capacity using in situ‐formed solid polymer electrolytes (SPEs) remain almost unchanged after various bending tests, a key criterion for flexible/wearable devices. Our study demonstrates an approach for SSEs that fulfill the requirement of no liquid and mechanical robustness for practical solid‐state Zn batteries.

Impact of ionic liquid on lithium ion battery with a solid poly(ionic liquid) pentablock terpolymer as electrolyte and separator

In this study, the physical, transport, mechanical, morphological, and electrochemical properties of a ternary blend solid polymer electrolyte (SPE) (poly(ionic liquid) (PIL) multiblock polymer, lithium salt, and ionic liquid (IL)) were systematically investigated as a function of IL concentration. With increasing IL concentration, the conductive volume increases along with the polymer chain segmental mobility. This facilitates high ionic conductivity, while the mechanical modulus exhibits a percolation threshold. Surprisingly, at higher IL concentrations, there is a reduction in the lithium cation mobility as evidenced by pulsed-field gradient nuclear magnetic resonance, which coincides with an increased overpotential evidenced by lithium metal stripping and plating. Stable lithium ion battery cycling durability (over 100 cycles at room temperature) is demonstrated with the ternary blend SPE as the electrolyte and separator. This work provides valuable insights into the design of new SPEs with both high ionic conductivity and improved battery stability.

Synthesis of Thermoplastic Poly(2-methoxyethyl acrylate)-Based Polyurethane by RAFT and Condensation Polymerization.

Thermoplastic solid poly(2-methoxyethyl acrylate) (PMEA)-based polyurethane (PU) is synthesized through the reversible addition-fragmentation chain transfer (RAFT) polymerization and the condensation polymerization, using hydroxyl-terminated RAFT reagents and diisocyanate, respectively. Neat PMEA is a promising antithrombogenic liquid used in the medical fields. The thermoplastic property of the solid PMEA-based PU due to hydrogen bonding is confirmed by the dynamic mechanical analysis (DMA) at temperature below 72 °C. The antithrombogenic property of PMEA-based PU is also analyzed by the platelet adhesion test. The number of platelets on PMEA-based PU is 17 cells per unit area, which is smaller than that on the fluorinated diamond-like carbon (F-DLC), a well-known highly antithrombogenic material. It is concluded that a newly synthesized PMEA-based PU exhibits thermoplastic characteristics with excellent antithrombogenicity.

Stabilized combustion of circular fuel duct with liquid oxygen

This research is an investigation of the flame spread opposed to a liquid oxidizer flow in a solid fuel duct. Several firing tests were conducted using liquid oxygen as the oxidizer and solid poly methyl methacrylate (PMMA) as the fuel. The results indicate that the flame spread rate decreased with increasing oxidizer port velocity and decreasing port diameter. This study reveals through visual confirmations and empirical correlations of the flame spread rate that the flame spread opposed to liquid oxygen in a solid fuel duct can be classified as stabilized combustion. Extinction and abnormal regression were observed when oxidizer port velocity was high and port diameter was small. Furthermore, the cooling of the solid fuel by the liquid oxygen flow had a strong effect on the transition between normal regression and extinction, or abnormal regression. A model of the flame spread rate which considers the heat balance at the fuel surface assuming a fully developed thermal boundary layer is introduced and shown to agree well with the experimental results. Lastly, it is revealed that the difference in kinematic viscosity between liquid oxygen and gaseous oxygen is the main reason dependency of port diameter on flame spread rates differs between the liquid oxygen tests in this study and gaseous oxygen tests in previous studies.

Exploiting Lipid and Polymer Nanocarriers to Improve the Anticancer Sonodynamic Activity of Chlorophyll.

Sonodynamic therapy is an emerging approach that uses low-intensity ultrasound to activate a sonosensitizer agent triggering its cytotoxicity for selective cancer cell killing. Several molecules have been proposed as sonosensitizer agents, but most of these, as chlorophyll, are strongly hydrophobic with a low selectivity towards cancer tissues. Nanocarriers can help to deliver more efficiently the sonosensitizer agents in the target tumor site, increasing at the same time their sonodynamic effect, since nanosystems act as cavitation nuclei. Herein, we propose the incorporation of unmodified plant-extracted chlorophyll into nanocarriers with different composition and structure (i.e., liposomes, solid lipid nanoparticles and poly(lactic-co-glycolic acid) nanoparticles) to obtain aqueous formulations of this natural pigment. The nanocarriers have been deeply characterized and then incubated with human prostatic cancer cells (PC-3) and spheroids (DU-145) to assess the influence of the different formulations on the chlorophyll sonodynamic effect. The highest sonodynamic cytotoxicity was obtained with chlorophyll loaded into poly(lactic-co-glycolic acid) nanoparticles, showing promising results for future clinical investigations on sonodynamic therapy.

Fast Li+ Conduction Mechanism and Interfacial Chemistry of a NASICON/Polymer Composite Electrolyte.

The unclear Li+ local environment and Li+ conduction mechanism in solid polymer electrolytes, especially in a ceramic/polymer composite electrolyte, hinder the design and development of a new composite electrolyte. Moreover, both the low room-temperature Li+ conductivity and large interfacial resistance with a metallic lithium anode of a polymer membrane limit its application below a relatively high temperature. Here we have identified the Li+ distribution and Li+ transport mechanism in a composite polymer electrolyte by investigating a new solid poly(ethylene oxide) (PEO)-based NASICON-LiZr2(PO4)3 composite with 7Li relaxation time and 6Li → 7Li trace-exchange NMR measurements. The Li+ population of the two local environments in the composite electrolytes depends on the Li-salt concentration and the amount of ceramic filler. A composite electrolyte with a [EO]/[Li+] ratio n = 10 and 25 wt % LZP filler has a high Li+ conductivity of 1.2 × 10-4 S cm-1 at 30 °C and a low activation energy owing to the additional Li+ in the mobile A2 environment. Moreover, an in situ formed solid electrolyte interphase layer from the reaction between LiZr2(PO4)3 and a metallic lithium anode stabilized the Li/composite-electrolyte interface and reduced the interfacial resistance, which provided a symmetric Li/Li cell and all-solid-state Li/LiFePO4 and Li/LiNi0.8Co0.1Mn0.1O2 cells a good cycling performance at 40 °C.

Thermal analysis studies on the compatibility of furosemide with solid state and liquid crystalline excipients

In the context of the present study, the thermal behavior of furosemide and the solid state excipients, sodium alginate, poly(ethylene oxide), poly(vinylpyrrolidone), lactose mono-hydrate and magnesium stearate, using Differential Scanning Calorimetry (DSC), was probed. It was found that the thermal behavior of these solid-state pharmaceutical excipients and furosemide correlates nicely with the literature relevant data. Regarding the furosemide-excipients mixtures, the DSC scans appear as a compilation of the thermal curves of each excipient. This suggests that the formulations containing these mixtures, may retain their stability over time. This information, which arises from the cooperativity of materials, their thermal stability and behavioris very helpful for the research and development of safe and effective pharmaceutical formulations. DSC experiments were also carried out with chimeric bilayers (called ?liposomes?), composed of hydrogenated soy phosphatidylcholine (HSPC) and poly(n-butylacrylate)-b-poly(acrylic acid) block copolymer with 70 % content of poly(acrylic acid (PnBA-b-PAA 30/70) with the addition of furosemide at the molar ratio of 9:0.1:1.0 in the system HSPC:PnBA-b-PAA 30/70:furosemide. Chimeric liposomal systems were characterized as ?fluid-like? by their DSC curves, which may be potentially translated as an easy way for release of furosemide from the advanced delivery system.

Ultrasmall TPGS-PLGA Hybrid Nanoparticles for Site-Specific Delivery of Antibiotics into Pseudomonas aeruginosa Biofilms in Lungs.

Inhaled antibiotic treatment of cystic fibrosis-related bacterial biofilm infections is challenging because of the pathological environment of the lungs. Here, we present an "environment-adaptive" nanoparticle composed of a solid poly lactic-co-glycolic acid (PLGA) core and a mucus-inert, enzymatically cleavable shell of d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) for the site-specific delivery of antibiotics to bacterial biofilms via aerosol administration. The hybrid nanoparticles with ultrasmall size were self-assembled via a nanoprecipitation process by using a facile microfluidic method. The interactions of the nanoparticles with the biological barriers were comprehensively investigated by using cutting-edge techniques (e.g., quartz crystal microbalance with dissipation monitoring, total internal reflection fluorescence microscopy-based particle tracking, in vitro biofilm model cultured in a flow-chamber system, and quantitative imaging analysis). Our results suggest that the mucus-inert, enzymatically cleavable TPGS shell enables the nanoparticles to penetrate through the mucus, accumulate in the deeper layer of the biofilms, and serve as sustained release depot, thereby improving the killing efficacy of azithromycin (a macrolide antibiotic) against biofilm-forming Pseudomonas aeruginosa. In conclusion, the ultrasmall TPGS-PLGA hybrid nanoparticles represent an efficient delivery system to overcome the multiple barriers and release antibiotics in a sustained manner in the vicinity of the biofilm-forming bacteria.

A composite membrane based on PTFE and solid poly (mixed acid (PMo12O40)X-(PO-OH)Y) for high-temperature fuel cells

A novel high-temperature proton exchange membrane (PEM) (PTFE/(PMo12O40)X-(PO-OH)Y composite membranes) was prepared by impregnating mixed acid into the porous PTFE membrane. The porous PTFE membrane serves as the support structure of the membrane, and (PMo12O40)X-(PO-OH)Y sol is used as the proton conductor. The solid poly acid (PMo12O40)X-(PO-OH)Y exhibits a proton conductivity of 0.025 S cm−1 at 180 °C, and the PTFE/(PMo12O40)X-(PO-OH)Y membrane presents a good proton conductivity (0.02 S cm−1) when the relative humidity is below 0.5% and temperature is 180 °C. Besides, the PTFE/(PMo12O40)X-(PO-OH)Y membrane performs moderate property as tested in hydrogen fuel cells. SEM and EDX reveal that the structure of (PMo12O40)X-(PO-OH)Y gel is uniformly distributed in the pores of PTFE, which enhanced the proton conductivity of the composite membranes.

Photo-charging polymeric sodium-ion cell based on YSZ/PVDF film

A cost-effective, light-weighted, and easy to handle photochargeable Na-ion power cell (NPPC) has been demonstrated by integrating solar active solid electrolyte poly(vinyl alcohol)-carbon black-V2O5-Na2SO4 and a high dielectric YSZ/PVDF film in a very simple and unique way. An open circuit voltage of ∼1.18 V is obtained under photocharging of the NPPC by light with an intensity of ∼110 mW/cm2. The discharging phenomenon is investigated at a constant discharge current density of ∼0.63 mA/cm2. The reversible charging-discharging nature of the device is recorded repeatedly for 200 cycles to investigate the storage capacity. A maximum capacitance of ∼ 2.84 mF/cm2 is obtained with an energy density and a power density of ∼5.6 mWhr/m2 and ∼ 7.4 W/m2, respectively. The high storage impact of NPPC is realized in practical by glowing blue light emitting diodes for two days with high intensity.

Facile synthesis of narrow particle size distribution, high solid content, cationic polymer latexes by macroemulsion polymerization-based particle coagulation mechanism

In this study, a novel approach for preparing 50 wt% solid content cationic poly(methyl methacrylate) (PMMA) latexes with narrow particle size distribution (PSD) using macroemulsion polymerization was proposed. The particle number trend firstly decreased followed by rapid particle size growth during particle nucleation stage, which was different from behavior of anionic latex. The former was explained through particle coagulative mechanism. The effects of reaction parameters, such as surfactant, comonomer and electrolyte concentration on the kinetics of polymerization were discussed. Narrow PSD and stable PMMA latexes with particle size ranging from 137 to 307 nm were obtained during the polymerization reaction step. Overall, the proposed approach could effectively improve the industrial production efficiency of cationic polymer latexes.

Mass spectrometric assay of high radiopurity solid polymer materials for parts in radiation and rare event physics detectors

Abstract Plastic dielectric materials are required in radiation and rare event physics detectors as structural parts, insulators, seals, light reflectors, and in connectors. In order to observe events of interest rather than counting the radioactivity of the detector itself, these materials must be of high radiopurity. Using a mass spectrometric method, a number of solid plastic materials and parts were analyzed for mass levels of contaminants 232 Th and 238 U, which were used as an assessment of radiopurity. Sample preparation began with dry ashing the solid subsamples in very low mass containers of ultra low background electroformed copper (ULB EF-Cu) foil that had been cut and folded into boats serving as crucibles. Final determinations were carried out by inductively coupled plasma mass spectrometry (ICP-MS) with liquid nebulization sample solution introduction. Sample sizes were in the 25 mg to 1.25 g mass, and analyses could be completed in less than two days. Detection limits to pg/g (i.e, parts per trillion) levels are obtained and converted to radioactivity units μ Bq/kg of material. Determinations on poly(methyl methacrylate) (PMMA) gave values for 238 U below 10 μ Bq/kg, while values for poly(chlorotrifluoroethylene) (PCTFE) rod stock material or acid-leached machined PCTFE parts were at or below 50 μ Bq/kg in 238 U. Results for solid Purad poly(vinylidene fluoride) (PVDF) material are also reported at ca 5 mBq/kg of 238 U, although PVDF Solef 1010 raw material in powder and pellet form has been previously reported as low as 25 μ Bq/kg, and 200 μ Bq/kg 238 U, respectively. An analysis of a polyetherimide (PEI) material, sold as ULTEM, indicated promising radiopurity with a found value of 30 μ Bq/kg for 238 U. A variety of solid dielectric polymer materials were found with radiopurities at less than a mBq/kg 238 U and 232 Th.

Controlled Graphene Synthesis from Solid Carbon Sources

Here the authors present the investigation of controllable growth of large area high quality graphene from different solid carbon sources. A home‐made cold‐wall chamber is used for chemical vapor deposition realization to grow graphene on copper foils. It is supplied with tools for in situ monitoring the temperature along the entire sample. Monolayer graphene films are synthesized using solid poly(methyl methacrylate) (PMMA) and paraffin precursors at a growth temperature of about 850 °C and under low pressure conditions. The area of 1 × 1 cm2 appears to be covered by graphene. Raman spectroscopy and scanning electron microscopy are used to estimate the quality of graphene films fabricated and the graphene layer number.

Thickness Changes in Temperature-Responsive Poly(N-isopropylacrylamide) Ultrathin Films under Ambient Conditions.

In this paper, we report detailed experimental observations of unusual changes in the thickness of solid poly(N-isopropylacrylamide) (PNIPAM) ultrathin films, which are well known to have temperature-responsive hydrophilic–hydrophobic switching properties. To date, a number of studies have been carried out on the bulk and the brush forms of PNIPAM in contact with liquid water, as well as in highly humid environments, and, recently, these ultrathin films have been preliminarily shown to exhibit temperature responses even under low-humidity, ambient conditions. In this work, the thicknesses of ultrathin PNIPAM films in a temperature/moisture-controlled sample stage were monitored continuously using multichannel X-ray reflectometry. At room temperature, the sample thickness showed an unexpected increase after thermal treatment at 70 °C for 3 h. In the temperature cycle between 15 and 60 °C, heating and cooling resulted in some clear differences. During cooling, initially, the thickness was almost constant but began to increase when the temperature exceeded 33 °C, which corresponds to the lower critical solution temperature (LCST). This observation indicates that the PNIPAM ultrathin film is sensitive to the small amounts of water contained in the air, even under ambient, low-humidity conditions. On the other hand, during heating run from 15 to 60 °C, the humidity dependence was monotonic, and no specific changes in the PNIPAM films were observed at around the LCST. By studying the humidity dependence, we found that the hydrophilic and hydrophobic states of the PNIPAM ultrathin film exhibit different temperature dependence behaviors. In addition, we found that swelling takes place even under low-moisture conditions. To understand the difference in the thickness changes observed on cooling and heating further, some models considering the effect of the boundary conditions in the polymer ultrathin film system were considered. In the case of the ultrathin film, the hydrophilic/hydrophobic switching property occurred only in the surface layer, which dominated the absorption of water molecules from air. In contrast, the interface layer was time-stable and provided an escape route for water molecules during heating.

Organoiridium(III) Complexes as Luminescence Color Switching Probes for Selective Detection of Nerve Agent Simulant in Solution and Vapor Phase.

In this work, cationic organoiridium(III) complex based photoluminescent (PL) probes have been developed to selectively detect the chemical warfare nerve agent mimic, diethyl chlorophosphate(DCP) at nanomolar range by distinct bright green to orange-red luminescence color switching (on-off-on) in solution as well as in the vapor phase. Interference of other chemical warfare agents (CWAs) and their mimics was not observed either by PL spectroscopy or with the naked-eye in solution and gas phase. The detection was attained via a simultaneous nucleophilic attack of two -OH groups of the 4,7-dihydroxy-1,10-phenanthroline ligand with DCP by forming bulkier phosphotriester. The detailed reaction mechanism was established through extensive 1H NMR titration, 31P NMR, and ESI-MS analysis. Finally, a test paper strip and solid poly(ethylene oxide) (PEO) film with iridium(III) complex 1[PF6] were fabricated for the vapor-phase detection of DCP. The solution and vapor-phase detection properties of these luminescent Ir(III) complexes can offer a worthy approach into the design of new metal complex based PL switching probes for chemical warfare agents.

Nanostructured polymers with embedded self-assembled networks: reversibly tunable phase behaviors and physical properties.

1,3:2,4-Dibenzylidene sorbitol (DBS) can self-assemble into nanofibrillar networks to form organogels in a variety of organic solvents and liquid polymers. In this study, we induced the formation of organogels in solid poly(ethylene glycol) (PEG) polymers. The DBS gels appeared at temperatures above the melting point of PEG. When the DBS/PEG systems were heated at higher temperatures, they exhibited transparent, clear solution states due to the collapse of the DBS networks. Upon cooling to room temperature, the DBS self-assembled nanostructures appeared again, followed by the solidification (crystallization) of PEG. These DBS/PEG systems possess three different phases (solid, gel and liquid) and can be tuned by changes in the composition and temperature. Using polarized optical microscopy, all the gel systems were found to exhibit spherulite-like morphologies. Small-angle X-ray scattering results revealed lamellar packing in these spherulite-like morphologies. Transmission electron microscopy verified that these features were formed due to the presence of DBS nanofibrillar networks consisting of fibrils that were approximately 10-20 nm in diameter. In addition, the crystallization of PEG was strongly templated by the existing DBS nanofibrils. Moreover, there were no significant distortions in the PEG crystal structures due to the confinement of PEG between the DBS nanofibrils.