The inherent hydrolytic reactivity of polyesters renders them excellent candidates for a variety of biomedical applications. Incorporating ionic groups further expands their potential impact, ...encompassing charge-dependent function such as deoxyribonucleic acid (DNA) binding, antibacterial properties, and pH-responsiveness. Catalyst-free and solvent-free polycondensation of a bromomethyl imidazolium-containing (BrMeIm) diol with neopentylglycol (NPG) and adipic acid (AA) afforded novel charged copolyesters with pendant imidazolium sites. Varying ionic content influenced thermal properties and offered a wide-range, −41 to 40 °C, of composition-dependent glass transition temperatures (T gs). In addition to desirable melt and thermal stability, polyesters with ionic concentrations ≥15 mol % readily dispersed in water, suggesting potential as nonviral gene delivery vectors. An electrophoretic gel shift assay confirmed the novel cationic copolyesters successfully bound DNA at an N/P ratio of 4 for 50 mol % and 75 mol % charged copolyesters (P(NA50-co-ImA50) and P(NA25-co-ImA75)), and an N/P ratio of 5 for 100 mol % Im (PImA). Polyplexes exhibited insignificant cytotoxicity even at high concentrations (200 μg/mL), and a Luciferase transfection assay revealed the ionic (co)polyesters transfected DNA significantly better than the untreated controls. The successful transfection of these novel (co)polyesters inspires future imidazolium-containing polyester design.
A new synthetic strategy using melt transesterification enabled selective control of ionic charge placement into the hard segment or soft segment block of segmented copolyesters. Dynamic mechanical ...analysis of sulfonated soft segment copolyesters revealed an increase in the low-Tg transition and rubbery plateau storage modulus as a function of sulfonation level. Sulfonated hard segment copolyesters displayed similar rubbery plateau moduli and decreasing flow temperature from 145 to 90 °C. Dynamic melt rheology and in situ, variable temperature small-angle X-ray scattering determined the non-sulfonated copolyester order-disorder transition at 150 ± 5 °C, which was ∼60 °C above the hard segment Tg. Atomic force microscopy revealed sulfonated hard segment copolyesters contained more disordered surface morphologies. Sulfonated soft segment copolyesters demonstrated increased tensile stress and improved tensile strain from 18 to 170% with increasing ion content. The enhanced mechanical performance of sulfonated soft segment was attributed to the preserved microphase-separated morphology and the presence of physical crosslinks from electrostatic interactions.
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Direct-write 3D printing enables the fabrication of three-dimensional objects via the extrusion from a nozzle. Stimuli responsive materials that shear-thin are well-suited as inks for these 3D ...printing systems. Poly(isopropyl glycidyl ether)-block-poly(ethylene oxide)-block-poly(isopropyl glycidyl ether) ABA triblock copolymers were synthesized using controlled ring-opening polymerization to afford dual stimuli-responsive polymers that respond to both shear forces and temperature. These polymers were demonstrated to form hydrogels in water. The gels were observed to be thermoreversibledriven by the lower critical solution temperature of the poly(isopropyl glycidyl ether) block which helps facilitate loading of the ink into the printer syringe. Rheological studies demonstrated that the gels had a rapid and reversible modulus response to shear stress. Thus, these materials were suitable as inks for direct-write 3D printing, as they were easily extruded during printing and maintained sufficient mechanical integrity which was necessary to support the next printed layer. Printed structures of high aspect ratio pillars and stacked layers were successfully demonstrated. These types of 3D hydrogel structures may ultimately have an impact in the biomedical field for applications such as tissue engineering.
Abstract Effective antimicrobial agents are important arsenals in our perennial fight against communicable diseases, hospital-acquired and surgical site multidrug-resistant infections. In this study, ...we devise a strategy for the development of highly efficacious and skin compatible yet inexpensive water-soluble macromolecular antimicrobial polyionenes by employing a catalyst-free, polyaddition polymerization using commercially available monomers. A series of antimicrobial polyionenes are prepared through a simple polyaddition reaction with both polymer-forming reaction and charge installation occurring simultaneously. The compositions and structures of polymers are modulated to study their effects on antimicrobial activity against a broad spectrum of pathogenic microbes. Polymers with optimized compositions have potent antimicrobial activity with low minimum inhibitory concentrations of 1.95–7.8 μg/mL and high selectivity over mammalian cells. In particular, a killing efficiency of more than 99.9% within 2 min is obtained. Moreover, the polymers demonstrate high antimicrobial efficacy against various clinically-isolated multidrug-resistant microbes, yet exhibit vastly superior skin biocompatibility in mice as compared to other clinically used surgical scrubs (chlorhexidine and betadine). Microbicidal activity of the polymer is mediated via membrane lysis as demonstrated by confocal microscopy. Unlike small molecular antibiotics, repeated use of the polymer does not induce drug resistance. More importantly, the polymer shows excellent bactericidal activity in a P. aeruginosa -contaminated mouse skin model. Given their rapid and efficacious microbicidal activity and skin compatibility, these polymers have tremendous potential to be developed as surgical scrubs/hand sanitizers to prevent multidrug-resistant infections.
Photopolymerization coupled with mask projection microstereolithography successfully generated various 3D printed phosphonium polymerized ionic liquids (PILs) with low UV light intensity requirements ...and high digital resolution. Varying phosphonium monomer concentration, diacrylate cross-linking comonomer, and display images enabled precise 3D design and polymeric properties. The resulting cross-linked phosphonium PIL objects exhibited a synergy of high thermal stability, tunable glass transition temperature, optical clarity, and ion conductivity, which are collectively well-suited for emerging electro-active membrane technologies. Ion conductivity measurements on printed objects revealed a systematic progression in conductivity with ionic liquid monomer content, and thermal properties and solvent extraction demonstrated the formation of a polymerized ionic liquid network, with gel fractions exceeding 95%.
Hemiaminal poly(ethylene glycol) (PEG)‐based organogels are formulated in polymerizable solvents. The dynamic‐covalent nature of the solvent‐H‐bonded hemiaminal crosslinks, together with the ...modification of the crosslinking density of the organogels allows for temperature‐dependent viscoelastic control. The shape of uncured gels can be permanently retained by templated UV‐curing of the solvent, offering great promise for complex manufacturing, printing, sealants, and materials repair.
Conventional melt transesterification successfully synthesized high molecular weight segmented copolyesters. The cycloaliphatic monomers 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) and ...dimethyl-1,4-cyclohexane dicarboxylate (DMCD) afforded sterically hindered, ester carbonyls in high-Tg polyester precursors. Reaction between the polyester polyol precursor and a primary or secondary alcohol at melt polymerization temperatures revealed reduced transesterification of the polyester hard segment as a result of enhanced steric hindrance adjacent to the ester linkages. Subsequent polymerization of a 4,000 g/mol polyol with monomers comprising the low-Tg block yielded high molecular weight polymers that exhibited enhanced mechanical properties compared to a non-segmented copolyester control. Atomic force microscopy uncovered unique needle-like, interconnected, microphase separated surface morphologies, and small-angle X-ray scattering confirmed the presence of bulk microphase separation. This new synthetic strategy enabled selective control of ionic charge placement into the hard segment or soft segment block of segmented copolyesters using melt transesterification. The ionic placement impacted the microphase-separated morphology, which influenced its thermomechanical properties and resulting mechanical performance. Melt transesterification of low-Tg, sodium sulfonated copolyesters achieved up to 15 mol% ionic content. The 10 and 15 mol% sodium sulfonated copolyesters exhibited water-dispersibility, which enabled cation dialysis exchanges to divalent metal cations. The sulfonated copolyesters containing divalent metal cations exhibited enhanced rubbery plateau moduli to higher temperatures. Novel trialkylphosphonium ionic liquids chain extenders enabled the successful synthesis of poly(ethylene glycol)-based, cationic polyurethanes with pendant phosphoniums in the hard segments (HS). Aqueous size exclusion chromatography (SEC) confirmed the charged polyurethanes, which varied the phosphonium alkyl substituent length (ethyl and butyl) and cationic HS content (25, 50, 75 mol%), achieved high absolute molecular weights. Dynamic mechanical analysis (DMA) demonstrated the triethylphosphonium (TEP) and tributylphosphonium (TBP) polyurethanes displayed similar thermomechanical properties, including increased rubbery plateau moduli and flow temperatures. Fourier transform infrared spectroscopy (FTIR) emphasized the significance of ion-dipole interaction on hydrogen bonding. Atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), and wide-angle X-ray diffraction (WAXD) supported microphase separated morphologies in the trialkylphosphonium polyurethanes, despite the presence of ionic interactions. Sorption isotherm experiments revealed TBP polyurethanes displayed similar water sorption profiles to the noncharged analogue and lower water absorptivity compared to TEP. The phosphonium polyurethanes displayed significantly improved tensile strain; however, lower tensile stress of the TEP polyurethane was presumably due to absorbed water. In addition, we also explored applications of the trialkylphosphonium polyurethanes as nucleic acid delivery vectors and demonstrated their abilities to form colloidally stable polyplexes in salt-containing media.
Conventional melt transesterification successfully synthesized high molecular weight segmented copolyesters. The cycloaliphatic monomers 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) and ...dimethyl-1,4-cyclohexane dicarboxylate (DMCD) afforded sterically hindered, ester carbonyls in high-Tg polyester precursors. Reaction between the polyester polyol precursor and a primary or secondary alcohol at melt polymerization temperatures revealed reduced transesterification of the polyester hard segment as a result of enhanced steric hindrance adjacent to the ester linkages. Subsequent polymerization of a 4,000 g/mol polyol with monomers comprising the low-Tg block yielded high molecular weight polymers that exhibited enhanced mechanical properties compared to a non-segmented copolyester control. Atomic force microscopy uncovered unique needle-like, interconnected, microphase separated surface morphologies, and small-angle X-ray scattering confirmed the presence of bulk microphase separation. ;
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This new synthetic strategy enabled selective control of ionic charge placement into the hard segment or soft segment block of segmented copolyesters using melt transesterification. The ionic placement impacted the microphase-separated morphology, which influenced its thermomechanical properties and resulting mechanical performance. Melt transesterification of low-Tg, sodium sulfonated copolyesters achieved up to 15 mol% ionic content. The 10 and 15 mol% sodium sulfonated copolyesters exhibited water-dispersibility, which enabled cation dialysis exchanges to divalent metal cations. The sulfonated copolyesters containing divalent metal cations exhibited enhanced rubbery plateau moduli to higher temperatures. ;
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Novel trialkylphosphonium ionic liquids chain extenders enabled the successful synthesis of poly(ethylene glycol)-based, cationic polyurethanes with pendant phosphoniums in the hard segments (HS). Aqueous size exclusion chromatography (SEC) confirmed the charged polyurethanes, which varied the phosphonium alkyl substituent length (ethyl and butyl) and cationic HS content (25, 50, 75 mol%), achieved high absolute molecular weights. Dynamic mechanical analysis (DMA) demonstrated the triethylphosphonium (TEP) and tributylphosphonium (TBP) polyurethanes displayed similar thermomechanical properties, including increased rubbery plateau moduli and flow temperatures. Fourier transform infrared spectroscopy (FTIR) emphasized the significance of ion-dipole interaction on hydrogen bonding. Atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), and wide-angle X-ray diffraction (WAXD) supported microphase separated morphologies in the trialkylphosphonium polyurethanes, despite the presence of ionic interactions. Sorption isotherm experiments revealed TBP polyurethanes displayed similar water sorption profiles to the noncharged analogue and lower water absorptivity compared to TEP. The phosphonium polyurethanes displayed significantly improved tensile strain; however, lower tensile stress of the TEP polyurethane was presumably due to absorbed water. In addition, we also explored applications of the trialkylphosphonium polyurethanes as nucleic acid delivery vectors and demonstrated their abilities to form colloidally stable polyplexes in salt-containing media.
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