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In order to protect the marine environment, traditional marine antifouling coatings such as tributyltin (TBT)‐based antifouling coatings have been phased out. There is an urgent need to develop environmentally friendly marine antifouling coatings. In this work, the antibacterial poly(hexamethylene guanidine) (PHMG) was introduced into polyurethane (PU) through chemical bond to prepare a green environmentally friendly marine antifouling coating (PU‐PHMG). The morphology, antimicrobial properties, mechanical properties and thermostability of the PU‐PHMG films were investigated. The antimicrobial rates of PU‐PHMG films against E. coli and S. aureus were both more than 99.9% when PHMG content in the films reached 1.0 wt%. The excellent antimicrobial activities can be maintained for more than 90 days due to the non‐leaching characteristic of PHMG. The growth of algae was also inhibited on the surface of PU‐PHMG films. The PU‐PHMG coating is promising for the applications in marine antifouling field. [ABSTRACT FROM AUTHOR]

A series of poly[methyl(trifluoropropyl)siloxane‐co‐silphenylenesiloxane] (PMTFPS‐co‐SPS) was synthesized by condensation polymerization of methyltrifluoro‐propylsiloxanediol and 1,4‐bis(dimethylsilyl)benzene. Their chemical structures were investigated using gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and dynamic thermomechanical analysis (DMA). The effect of silphenylenesiloxane (SPS) units on the thermal stability of poly[methyl(trifluoropropyl)siloxane] (PMTFPS) was studied by thermogravimetric analysis (TGA), isothermal degradation tests, quantum chemical calculation, and pyrolysis‐gas chromatography–mass spectrometry (Py‐GCMS). The results showed that the thermal stability of PMTFPS improved with the introduction of SPS units into the backbone. The temperature for 5% mass loss in PMTFPS increased by 63°C under a nitrogen atmosphere. Additionally, the mechanism by which the SPS units improve the thermal stability of PMTFPS was also investigated. [ABSTRACT FROM AUTHOR]

As an essential elastomer used in edge technologies, fluorosilicone rubber (FSR) suffers serious oxidative aging problem when serving at high temperature. In this study, a small amount of reduced graphene oxide (rGO) was added to FSR, and the resulting rGO/FSR compounds were vulcanized using 2,5‐dimethyl‐2,5‐di(tert‐butyl) peroxyhexane as the vulcanizer. The dispersion of rGO was investigated using scanning electron microscope. The mechanical properties and thermal‐oxidative stability of the rGO/FSR vulcanizates were investigated via thermal aging test at 230°C for 72 h, thermogravimetric analysis (TGA), and isothermal degradation test at 280, 320, and 350°C. The results showed the small addition of rGO (0.5 wt%) significantly improved the thermo‐oxidative stability of FSR. In particular, the FSR incorporating of 0.5 wt% of rGO could maintain more than 85% of tensile strength after aging at 230°C for 72 h. The FSR incorporating of 0.5 wt% of rGO can maintain more than 90% of initial weight after aging at 350°C for 12 h. The experiment of scavenging hydroxyl radical by rGO, and quantum chemistry calculation indicated rGO containing aryloxy radicals can scavenge the initial radicals during thermal degradation of FSR, which might be prime reason for the antioxidant properties of rGO. [ABSTRACT FROM AUTHOR]

The alkyl‐terminated poly(hexamethyleneguanidine hydrochloride) (PHMG‐L), which is antibacterial by physical membrane rupture, was selected as the functional gene, a nonleaching antimicrobial polymethyl methacrylate (PMMA) was developed by the melting grafting reaction between the random copolymer P (MMA‐co‐MAH) containing 5.0 wt% maleic anhydride (MAH) and the PHMG‐L. The results of Fourier transform infrared spectroscopy, X‐ray photoelectron spectra, energy spectrometer, atomic force microscope, scanning electron microscopy, elemental analyzer, UV–visible spectrophotometer confirmed that P(MMA‐g‐PHMG) had been successfully prepared, and the grafting efficiency was at 67.1%–70.7% while 1.0–3.0 wt% PHMG‐L was added. Furthermore, P(MMA‐g‐PHMG) was compatible with PMMA, and partially enriched on the surface of the mixture. The inhibition rates of antimicrobial PMMA with 3.0 wt% PHMG‐L against Escherichia coli and Staphylococcus aureus reached 99.9%, and the nonleaching characteristic ensured the safety and long‐term antimicrobial property. The antimicrobial PMMA also possessed excellent heat resistance and transparency. This study provides a green and promising approach for the industrial fabrication of antimicrobial PMMA. [ABSTRACT FROM AUTHOR]

A novel antimicrobial agent polypentamethylene guanidine hydrochloride (PPMG) was prepared by melt polycondensation with pentamethylenediamine and guanidine hydrochloride. The effects of reaction conditions on the molecular structure of PPMG were investigated. In order to develop value‐added down fibers with efficient and durable antibacterial performance, PPMG was grafted onto down fibers using glutaric dialdehyde as the coupling agent. It was confirmed that PPMG was successfully grafted onto down fibers through chemical bonding, and the grafting efficiencies were above 80%. The inhibition rates against Escherichia coli and Staphylococcus aureus of the modified down fibers reached over 99.9%, and such antimicrobial properties were still maintained after 20 washings with water or detergent. [ABSTRACT FROM AUTHOR]

Antimicrobial poly(vinyl alcohol) (PVA) hydrogels attracted much attentions in the last decade. In this work, a novel antimicrobial PVA hydrogel was prepared through compounding PVA with polyhexamethylene guanidine hydrochloride (PHMG) and freezing‐thawing method. These composite hydrogels behaved above 99.9% of antimicrobial rates against both Escherichia coli and Staphylococcus aureus even at 0.003 wt% of PHMG, and the nonleaching characteristic of PHMG as well as long‐acting antimicrobial activities. The PVA/0.100 wt% PHMG hydrogel had 120% higher tensile strength than pure PVA hydrogel, and its water vapor transmission rate was 4530 ± 245 g/m2/d, which was at an optimal range for injured skin (279‐5138 g/m2/d). This work provides a simple approach to develop nonleaching antimicrobial PVA hydrogels with extremely few PHMG for wound dressing and other potential applications in biomedical field. [ABSTRACT FROM AUTHOR]

Poly[methyl(trifluoropropyl)siloxane] (PMTFPS), which is an essential polymer in oil‐resistant rubber materials, exhibits unsatisfactory thermal stability. In this article, PMTFPSs with methyl and hydroxyl terminal groups are prepared, and their thermal stabilities are investigated via thermogravimetric analysis and pyrolysis‐gas chromatography‐mass spectrometry in an inert atmosphere. Additionally, the degradation mechanisms are discussed in terms of molecular structural characteristics (bond length and bond angle) and reaction driven forces (electrostatic potential and atom charge) based on quantum chemistry calculations. PMTFPS is found to degrade mainly into cyclic monomers through (a) the SiO rearrangement reaction in the middle of the chain and (b) the "back‐biting" reaction from the end of the chain. PMTFPS with silanol terminal groups is more likely to degrade according to pathway (b), resulting in more cyclotrisiloxane. Furthermore, the silanol from nano‐silica accelerates the degradation of PMTFPS, and the mechanism of this process is presented. [ABSTRACT FROM AUTHOR]

Antimicrobial polyamide (PA) received much attention for the demand of packaging and biomedical fields. In this paper, an antimicrobial PA6 membrane was prepared via a surface chemical reaction. A highly effective antibacterial component (PHMG‐E) with terminal epoxy group was firstly synthesized via a reaction between polyhexamethylene guanidine hydrochloride (PHMG) and ethylene glycol diglycidyl ether (EGDE). Then, PHMG‐E was bonded on the surface of PA6 membrane with secondary amine reduced by borane‐tetrahydrofuran (BH3‐THF). The antimicrobial rates of surface‐modified PA6 membrane (PA6‐PHMG) against Escherichia coli and Staphylococcus aureus were both higher than 99.99%, and the PHMG was non‐leaching due to the chemical bonding. The hydrophilicity of antibacterial PA6 membrane was also significantly improved and the mechanical performance became better. [ABSTRACT FROM AUTHOR]

In order to improve the flame retardancy of glass fibers (GFs) reinforced polyamide 6 (PA6) composites and eliminate the "wicking effect," the preparation and application of graphene oxide (GO) modified GFs were investigated in this work. Flame retardant PA6 was prepared by blending graphene oxide modified GFs reinforced PA6 and aluminum diethyl phosphonate. For the GFs reinforced PA6, the limiting oxygen index of the composite increased from 20.6% to 22.3%, and peak heat release rate decreased by 37.2% in cone calorimeter test via introducing graphene oxide onto the surface of GFs. Comparing PA6/GF30/ADP15 and PA6/GF‐GO30/ADP15, LOI of the later increased to 31.2%, the vertical burning test (UL‐94) reached V‐0, and the peak heat release rate decreased by 18.0%. The interface compatibility was greatly improved after the introduction of GO. The sheet structure of the GO on the GFs surface could block the combustible gas spillage and the flow of melt along the GFs, thus significantly attenuating the "wicking effect" and improving the flame retardancy of composites. [ABSTRACT FROM AUTHOR]

Recently, silicone rubber (VMQ) was extensively used in household articles and medical devices. To develop a kind of safe and long‐term antimicrobial VMQ was of great significance. In this work, a kind of vinyl‐contained polyhexamethylene guanidine hydrochloride (VPHMG) was synthesized and used as antimicrobial additive for VMQ. With the increasing of VPHMG addition, the mechanical properties and antimicrobial properties of VMQ‐VPHMG were significantly improved. In particular, the antimicrobial rates against Escherichia coli and Staphylococcus aureus were higher than 99.99% as for 4 wt% of VPHMG addition. Moreover, the surface concentration of VPHMG as well as the antimicrobial rates revealed almost unchanged after being extracted by water and methanol. All the results indicated the vinyl‐contained VPHMG vulcanization and therefore provided the permanent antimicrobial performance for VMQ. [ABSTRACT FROM AUTHOR]

In order to break through the bottleneck of anionic polymerization, polar monomers such as methyl methacrylate (MMA), ethyl methacrylate, butyl methacrylate, and hexyl methacrylate are subjected to anionic polymerization at room temperature in tetrahydrofuran (THF) using potassium tert‐butoxide (t‐BuOK) as the initiator. The polymerization of alkyl methacrylates is studied by multidetector gel permeation chromatography, proton nuclear magnetic resonance (1H‐NMR) and 13C‐NMR spectroscopy, and dynamic laser light scattering. It is found that t‐BuOK can initiate the living anionic polymerization of polar alkyl methacrylate, and the polymerization conversion almost reaches up to 100%. t‐BuOK exists into two kinds of agglomerates, whose hydrodynamic volumes are 10 and 80 nm, respectively. t‐BuOK in THF is similar to emulsion and has a critical active species concentration of about 0.0265 mol L−1 and does not depend on how much t‐BuOK is added. After the initiation of the polymerization, the large agglomerates of a loose and less regular structure that have occupied the main part of t‐BuOK are greatly reduced, but they do not continue to decrease until they disappear according to the equilibrium theory. Similarly, the active chain after initiation also will not aggregate again. Furthermore, t‐BuOK also has an active species with smaller average vibration size between cation and anion pairs, which can only initiate the polymerization of MMA with rather slow rate but cannot initiate other alkyl methacrylates. At last, because t‐BuOK can make the dormant species caused by side reactions to be revived, the anionic polymerization of MMA could obtain a high yield. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1130–1139 [ABSTRACT FROM AUTHOR]

ABSTRACT Antimicrobial polypropylene (PP) has been widely used. Its highly effective antimicrobial activities and nonleaching characteristics remain concerns. In this study, polypropylene wax (PPW) grafted with maleic anhydride was first prepared; this was followed by a melting reaction with polyhexamethylene guanidine hydrochloride (PHMG) to obtain antimicrobial PPW [polypropylene wax grafted with polyhexamethylene guanidine hydrochloride (PPW- g-PHMG)]. PPW- g-PHMG was then melt-blended with PP to prepare antimicrobial PP. Fourier transform infrared spectra confirmed that PHMG was covalently bonded on the PPW chains, and transmission electron microscopy images showed a uniform distribution of PHMG in the PPW matrix. The resulting antimicrobial PP exhibited excellent antimicrobial activity against Escherichia coli. The ring-diffusion test further disclosed its nonleaching characteristics. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44190. [ABSTRACT FROM AUTHOR]

ABSTRACT The thermal aging behavior of poly(3,3,3-trifluoropropyl)methylsiloxane was investigated by thermal gravimetric analysis and isothermal aging tests, and the results indicated the degradation mechanism II, oxidation scission of the side groups, played a more important role when the temperature was below 350 °C. The addition of ceria had significantly improved the thermal stability of fluorosilicone rubber (FSR) by inhibiting the oxidation scission. Moreover, two types of ceria including laminar-structure ceria (LS-CeO2) and nanoparticle ceria (N-CeO2) were prepared and surface was modified by KH570 and characterized by scanning electron microscopy, transmission electron microscope, and X-ray diffractometer. FSR incorporated with modified LS-CeO2 and N-CeO2 revealed a significant improvement on the heat resistant properties. In particular, after having been thermal oxidative aged for 70 h at 250 °C, FSR containing 2 wt % of modified N-CeO2 maintained 72.6% of tensile strength and 63.9% of elongation at break, respectively, while FSR without ceria completely failed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44117. [ABSTRACT FROM AUTHOR]

More information regarding the bactericidal properties of polyhexamethylene guanidine hydrochloride (PHMG) against clinically important antibiotic-resistant ESKAPE ( Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens needs to be provided for its uses in infection control. The bactericidal properties of PHMG and chlorhexidine digluconate (CHG) were compared based on their minimum inhibitory concentrations (MICs), minimum bactericidal concentrations, and time-course-killing curves against clinically important antibiotic-susceptible and antibiotic-resistant ESKAPE pathogens. Results showed that PHMG exhibited significantly higher bactericidal activities against methicillin-resistant Staphylococcus aureus, carbapenem-resistant Klebsiella pneumoniae, and ceftazidime-resistant Enterobacter spp. than CHG. A slight bactericidal advantage over CHG was obtained against vancomycin-resistant Enterococcus faecium, ciprofloxacin- and levofloxacin-resistant Acinetobacter spp., and multidrug-resistant Pseudomonas aeruginosa. In previous reports, PHMG had higher antimicrobial activity against almost all tested Gram-negative bacteria and several Gram-positive bacteria than CHG using MIC test. These studies support the further development of covalently bound PHMG in sterile-surface materials and the incorporation of PHMG in novel disinfectant formulas. [ABSTRACT FROM AUTHOR]

This work confirms the new view of the initiation and propagation mechanism of the anionic polymerization previously proposed, based on the investigation of anionic bulk-polymerization of styrene and α-methyl styrene with the help of a self designed microflow device and characterized by GPC and in situ 7Li NMR. It was found that n-BuLi tended to form the hexameric-aggregated structure and even to form the huge aggregated structure based on the former. These aggregations of initiators could directly initiate the anionic polymerization and form the supramolecule aggregations. The supramolecule aggregations inevitably blocked the diffusion of the monomers to the ion-pairs and resulted in a stationary-conversion platform. Then the aggregators were dissociated completely into equal binary-aggregated species, and the polymerization continued again rapidly before the termination. Tetrahydrofuran (THF) acted as the electron donator, which could push the electron cloud to Li cation and make the aggregated ring of the active species rather loosened and facilitated the monomer to insert in. Therefore, a little THF can greatly promote the anionic polymerization. However, further addition of THF might block the channel between the ion-pairs and decrease the propagation rate. It was also found that the aggregated structure of the active species during the anionic polymerization only depends on the initiator aggregations which were formed before the polymerization. [ABSTRACT FROM AUTHOR]

Two types of permanent antistatic agents, polyethylene wax grafted with sodium acrylate (PEW- g-AAS) and polypropylene (PP) wax grafted with sodium acrylate (PPW- g-AAS), were prepared using a solution grafting method and applied to PP to enhance antistatic properties. The grafting degree was determined using back titration method, and structures were confirmed by Fourier transform infrared spectroscopy. The antistatic properties of PEW- g-AAS/PP blends and PPW- g-AAS/PP blends were characterized by surface resistivities (ρ s) and volume resistivities (ρ v), and a combination of contact angle measurement, scanning electron microscopy, permittivity, and dielectric loss were used to investigate the surface and inner structures of the blends. Results showed that ρ s and ρ v of PEW- g-AAS/PP blends dropped significantly (four to seven orders of magnitudes) above a critical addition at 10%, where an electrostatic dissipative network formed; PPW- g-AAS revealed an inferior antistatic performance than PEW- g-AAS due to its better compatibility and smaller content of dispersed phase in the matrix. Furthermore, the antistatic blends treated in 80°C water, 80°C air, and room temperature were investigated, and the results were interpreted from surface energy. Moreover, the addition of antistatic agent had little impact on tensile strength of the PP matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Polyhexamethylene guanidine hydrochloride (PHMG) oligomer is attracting increasing attention for its highly efficient biocidal activity and nontoxicity. To make it bearing carbon-to-carbon double bonds and enlarge its application in production of antimicrobial materials via copolymerization, PHMG oligomer was modified via reaction with glycidyl methacrylate (GMA). The influence of reaction parameters on the conversion rate of GMA was investigated using ultraviolet absorption spectroscopy. The structures of PHMG oligomer before and after modification were characterized by Fourier transform infrared spectrometry, Raman spectrometry, nuclear magnetic resonance spectrometry, and electrospray ionization time-of-flight mass spectrometry. The results show that carbon-to-carbon double bond is successfully introduced into the modified PHMG oligomer. At a feeding molar ratio of GMA to PHMG of 1.0, the conversion rate of GMA reached up to 75% after 60 h of reaction at 60°C in dimethyl sulfoxide. Also, there is an activity difference in the different aminos of PHMG oligomer: the primary amino is ready to react with epoxy of GMA, while the guanidyl amino hardly reacts with GMA due to the p-π conjugation. Furthermore, the modified PHMG oligomer was used as comonomer to synthesize acrylonitrile copolymer, showing excellent antimicrobial activity against Staphylococcus aureus. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012 [ABSTRACT FROM AUTHOR]

Two types of permanent antistatic agents, polyethylene wax grafted with sodium acrylate (PEW- g-AAS) and polypropylene (PP) wax grafted with sodium acrylate (PPW- g-AAS), were prepared using a solution grafting method and applied to PP for enhancing antistatic properties. The grafting degree was determined using back titration method and structures were confirmed by Fourier transform infrared spectroscopy. The antistatic properties of PEW- g-AAS/PP blends and PPW- g-AAS/PP blends were characterized by surface resistivities (ρ s) and volume resistivities (ρ v), and a combination of contact angle measurements, scanning electron microscope, permittivity, and dielectric loss were used to investigate the surface and inner structures of the blends. Results showed ρ s and ρ v of PEW- g-AAS/PP blends dropped significantly (4-7 magnitudes) above a critical addition at 10%, where a electrostatic dissipative network formed; PPW- g-AAS revealed an inferior antistatic performance than PEW- g-AAS due to its better compatibility and smaller dispersed phase in the matrix. Further, the antistatic blends treated in 80°C water, 80°C air, and room temperature were investigated, and the results were interpreted from surface energy. Moreover, the addition of antistatic agent had little impact on tensile strength of the PP matrix. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

Initiating Mechanism of the Anionic Polymerization of Methacrylates with t-BuOK and the Synthesis of ABA Type Triblock Copolymers B Back Cover b : In article number 1900390, Anna Zheng, Yong Guan, and co-workers report that using I t i -BuOK as initiator, an ABA-type triblock copolymer (PMMA-b-PLMA-b-PMMA) is synthesized at 0 °C without using any sidereaction inhibitors and the monomer conversion is over 97%, which paves the way for the synthesis of thermoplastic elastomers with full polar monomers and full saturated chains by anionic polymerization. [Extracted from the article]

Abstract: It still remains a concern to break through the bottlenecks of anionic polymerization of polar monomers, such as side reactions, low conversion and low temperature (–78°C). In this work, potassium tert‐butoxide (t‐BuOK) was chosen to initiate the anionic polymerization of 2‐ethylhexyl methacrylate (EHMA) in tetrahydrofuran. The conversions were above 99% at 0 or 30°C, and above 95% at 60°C without side reaction inhibitors. The high conversions implied t‐BuOK could suppress the side reactions. A series of block copolymers of EHMA, n‐hexyl methacrylate (HMA) and methyl methacrylate (MMA) were further synthesized at 0°C, and the conversions were all above 99%. The GPC and 1H NMR results confirmed the successful synthesis of the block copolymers. The molecular size of monomer and the state of t‐BuOK (free ion pairs or aggregates) remarkably affected the polymerization rates and the molecular structures of the products. The DMA results indicated that the glass transition temperatures of PEHMA or PHMA block and PMMA block were 20°C and 60°C, respectively, which deviated from –2°C and 105°C of homopolymer, respectively, due to the partial compatibility of the blocks. This work explored a route of the anionic polymerization of polar monomers at room temperature. [ABSTRACT FROM AUTHOR]