Polymerization Phase Separation Research Articles

Polar groups promoting in-situ polymerization phase separation for solid electrolytes enabling solid-state lithium batteries

Plastic-crystal-embedded elastomer electrolytes (PCEEs), produced through polymerization-induced phase separation (PIPS), are gaining popularity as solid polymer electrolytes (SPEs). However, it remains to be investigated whether all monomer molecules can achieve polymerization-induced phase separation and the corresponding differences in lithium metal battery performance. Herein, we prepared PCEEs with different functional groups (OH, CN, F) through in situ polymerization. Research findings show that PCEE containing – CN or – F achieves the separation of the plastic crystalline phase and succinonitrile (SN) phase, whereas PCEE containing OH cannot due to hydrogen bonding with the SN phase. Notably, the PCEE synthesized with the F monomer (FBA-PCEE) exhibited exceptional interfacial stability with lithium metal anodes and lithium iron phosphate (LFP) cathodes, due to its unique coordination mechanism with lithium ions. The FBA-PCEE demonstrated a high ionic conductivity (2.02 × 10−3 S cm−1) and lithium-ion migration number (tLi+ = 0.75). Moreover, lithium symmetric cells incorporating FBA-PCEE demonstrated stable cycling performance for more than 1000 h at a current density of 0.1 mA cm−2, resulting in the development of a solid electrolyte interphase (SEI) rich in LiF, Li3N, and Li2CO3 over time. Additionally, incorporating FBA-PCEE facilitated the stable cycling of LPF over 1000 cycles at 0.5C, maintaining a capacity retention of 77.38 % after 500 cycles. When coupled with high-voltage Nickel Cobalt Manganese Oxide (NCM-622) cathodes and lithium metal anodes, a discharge capacity of 119.70 mAh g−1 at 0.1C was sustained after 100 cycles, exhibiting a capacity retention of 78.95 %. This study elucidates the critical role of monomer design in achieving PIPS, offering valuable insights into developing high-performance polymer composite electrolytes for advanced lithium metal batteries.

Membrane Engineering: Phase Separation in Polymeric Giant Vesicles.

Cell membranes exhibit elaborate lipidic patterning to carry out a myriad of functions such as signaling and trafficking. Domain formation in giant unilamellar vesicles (GUVs) is thus of interest for understanding fundamental biological processes and to provide new prospects for biocompatible soft materials. Lipid rearrangements in lipidic GUVs and lipid/polymer GUVs are extensively studied whereas polymer/polymer hybrid GUVs remain evasive. Here, the focus is on the thermodynamically driven phase separation of amphiphilic polymers in GUVs. It is demonstrated that polymer phase separation is entropically dictated by hydrophobic block incompatibilities and that films topology can help to determine the outcome of polymeric phase separation in GUVs. Lastly, Janus-GUVs are obtained and GUVs exhibit a single large domain by using a compatibilizing hydrophobic block copolymer.

Emerging role of polyethylene glycol on doxycycline hyclate-incorporated Eudragit RS in situ forming gel for periodontitis treatment

Phase separation with solvent exchange induced-in situ forming gel (ISG) is an attractive delivery system for periodontitis treatment. Eudragit® RS-PO (ERS) in N-methyl pyrrolidone (NMP) was used as polymer matrix for doxycycline hyclate (DH)-loaded solvent-exchanged ISG; however, a high burst drug release was evident. The present study revealed the role of PEG 1500 on physicochemical properties and modification of a burst release for DH-loaded ISG. DH-loaded ISG system comprising PEG 1500 exhibited the Newtonian flow with acceptable injectability with PEG 1500 concentration dependence and high in vitro degradation owing to NMP and PEG 1500 liberation. Solvent exchange between NMP with PBS pH 6.8 conveyed the rapid phase separation of ERS/PEG 1500 as a matrix which the entrapped DH diffused out gradually. Both dialysis membrane and membrane-less methods proved the slower drug release of DH-loaded ERS ISG comprising PEG than PEG 1500-free ISG. SEM revealed the porous matrix topography from polymeric phase separation especially for higher PEG 1500 loading. PEG 1500 incorporation significantly decreased the inhibition diameter against S. aureus, E. coli and S. mutans (P < 0.05) indicating the retardation of drug release owing to the high viscosity of the PEG 1500. PEG 1500-incorporated DH-loaded ERS ISG exhibited the potential use for periodontitis treatment. PEG loading into solvent induced ERS in situ forming gel for doxycycline hyclate periodontal pocket delivery.

Preparation and characterization of low gloss aqueous coating via forming self-roughed surface based on waterborne polyurethane acrylate hybrid emulsion

Abstract A series of low gloss waterborne polyurethane acrylate (WPUA) hybrid emulsions with different weight ratios of hard/soft monomers of acrylic monomers were synthesized successfully. Compared with the traditional low gloss coatings that achieve low gloss effects by adding a large number of pigments, fillers or both to roughen the surfaces, the low gloss effect of these WPUA emulsions was achieved through the formation of self-roughed surfaces during film formation with zero loading of extraneous dulling agent. Gloss levels could be as low as 3 units at 60° incident angle. The chemical structures of these WPUA films were characterized by nuclear magnetic resonance carbon spectroscopy ( 13 C NMR), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The rough surface topographies of these WPUA films were observed by scanning electron microscopy (SEM). The particle size distributions of these WPUA emulsions were analyzed by DLS measurement. The polymeric phase separation behaviors of these WPUA films were assessed by DSC analysis. In general, the WPUA emulsions that afforded films with good hardness, good adhesion strengths and excellent thermal stabilities, showed a great advantage in applications of low gloss aqueous coating.

Characterization of immiscibly blended polyurethane coatings part 1: selective staining for enhanced micro-Raman spectroscopy

Raman spectroscopy (RS) mapping of the selective infiltration of styrene monomer has been developed as a protocol for polymeric phase identification in resin-blended thermoset powder coatings. Blends of incompatible acrylic polyols, with low and high hydroxyl contents, combined with matting agents and pigments, were crosslinked to produce unique low gloss thermosets. The low reflectance originated from a synergistic effect between the polymeric phase separation and the incorporation of the matting agents and pigments. RS conclusively identified the phases within the blended film using polyester-embedded cross-section samples. Further analysis has revealed that monomeric styrene from the polyester-embedding resin produced the spectroscopic handle necessary for domain identification. Preferential infiltration of styrene was therefore investigated through dip and vapor staining of the blended and individual resin films. The spectroscopic handle had manifested through the consistent infiltration of styrene within the low hydroxyl film. The contamination in the cross-sections was eliminated when an epoxy-embedding resin was utilized, which produced no such marker peak in the ensuing spectra. These observations led to the development of the described selective staining protocol for micro-Raman analysis, which enabled very reproducible results for enhanced chemical mapping of phase-separated coatings.

Poly(styrene-methyl methacrylate) microcapsules prepared by ultrasonically initiated miniemulsion polymerization phase separation method

Ultrasonically initiated miniemulsion polymerization phase separation was employed to prepare poly(styrene-methyl methacrylate) (P(St-co-MMA)) microcapsules. The results of a thermal analysis revealed that it was difficult to form a microcapsule structure from neat styrene (St). However, MMA shows improved interface conditions due to its higher hydrophilicity than St. Therefore, it was easier to form hollow structures because the polymer microcapsules had a lower interface free energy per unit area. The results of dynamic light scattering (DLS), transmission electron microscopy (TEM) and atomic force microscopy (AFM) showed that P(St-co-MMA) microcapsules were uniform in size (about 100 nm in diameter and 20–25 nm in shell thickness).

Kinetics of phase separation in polymer mixtures: A molecular dynamics study

We present detailed results from a molecular dynamics (MD) simulation of phase-separation kinetics in polymer mixtures. Our MD simulations naturally incorporate hydrodynamic effects. We find that polymeric phase separation (with dynamically symmetric components) is in the same universality class as segregation of simple fluids: the degree of polymerization only slows down the segregation kinetics. For d = 2 polymeric fluids, the domain growth law is L(t) ∼ t(ϕ) with ϕ showing a crossover from 1/3 → 1/2 → 2/3. For d = 3 polymeric fluids, we see the crossover ϕ = 1/3 → 1. Our MD simulations do not yet access the inertial hydrodynamic regime (with L ∼ t(2/3)) of phase separation in 3-d fluids.

An Efficient and Environmentally Friendly Method for the Preparation of PMMA Microcapsules

Polymer microcapsule is a kind of functional material with unique structure. Study on the preparation methods is growing obviously. An efficient and environmentally friendly method for the preparation of polymer microcapsules is presented in this article. PMMA microcapsules were prepared by ultrasonically initiated miniemulsion polymerization phase separation method. The morphology, size and its distribution of PMMA microcapsules were investigated by transmission electron microscopy (TEM), atomic force microscopy (AFM) and dynamic light scattering (DLS). And the polymerization kinetics was also discussed. The results show that PMMA microcapsules with size of ca. 100 nm can be obtained when the amount of coemulsifier is 3 times of that of the emulsifier, the amount of monomer is 3 wt% of the system and the reaction temperature is 80°C. In all experiments, N2 was bubbled to protect the reaction system.

Preparation of multi-layered film of hydroxyapatite and chitosan

We present flexible nacre-like multi-layered films of chitosan and hydroxyapatite using manipulation of inherited polymeric phase separation in the solidification process. Films were characterized as homogeneous dispersity, high mechanical strength, and ordered microstructure in given optimized conditions of temperature and composite ratio. It resulted that the initial solidification temperature and the composition ratio are important factors in determination of homogeneity and mechanical strength of organic/inorganic composites. These films might be suitable for further osteological applications with surgical appliances, wound dressings, and space-filling implants.

Thermo-mechanical analysis of a compliant poly(carbonate-urea)urethane after exposure to hydrolytic, oxidative, peroxidative and biological solutions

Aims: To date, there is still a great need for a fully viable small diameter (<6 mm) polymeric vascular graft. Currently in such low flow locations, non-elastic expanded polytetrafluoroethylene (ePTFE) is the best available but it is quite inferior to autologous saphenous vein since it fails due to intimal hyperplasia caused by compliance mismatch between the graft and elastic host artery. Recently, a novel compliant poly(carbonate-urea)urethane vascular graft whose trade name is MyoLink™ has been developed. In this article, we report the findings of a thermo-mechanical analysis of the polymers chemistry postexposure to in vitro solutions comprised of hydrolytic, oxidative, peroxidative and biological media. Methods and materials: The following degradative solutions were used in vitro: plasma fractions I–IV; phospholipase A 2 (PLA); cholesterol esterase (CE) and solutions of H 2O 2/CoCl 2, t-butyl peroxide/CoCl 2 (t-but/CoCl 2) and glutathione/t-butyl peroxide/CoCl 2 (glut/t-but/CoCl 2). The MyoLink graft was compared against a conventional poly(ether)urethane (Pulse-Tec). All the graft specimens were 100 mm in length (5.0 mm ID) and were incubated in the latter solutions at 37°C for 70 days in total. The following thermo-mechanical methods were used to analyse both graft types: thermo-mechanical analysis (TMA) and dynamic mechanical thermal analysis (DMTA). Results: Incubation of Pulse-Tec in plasma fractions I–IV, PLA and CE reveals only one observable modification: an increase in the size of the low temperature, melting phase. But incubation in H 2O 2/CoCl 2, and t-but/CoCl 2 leads to an increase in the polymeric phase separation coupled with an enlargement in the size of the low temperature melting crystalline phase in Pulse-Tec. The glut/t-but/CoCl 2 solution leads to a phase separation between the hard and soft segment domains, coupled with an increase of the internal order within the hard segment domains in Pulse-Tec. The only system in which MyoLink degraded was glut/t-but/CoCl 2. In this system, an increase of the phase separation coupled with a simultaneous increase of the crystal size of the low-temperature melting crystalline phase occurred. Conclusion: This study shows dramatic changes in the chemistry of the soft and hard segments occurred in the case of the conventional poly(ether)urethane Pulse-Tec graft material. Such changes were not manifested in the majority of solutions in the case of MyoLink but a hydrolytic-led degradation of the carbonate soft segment was evidenced only in the glut/t-but/CoCl 2 system.