Preparation and properties of novel biodegradable polyurethane networks based on castor oil and poly(ethylene glycol)

Polyurethane networks based on castor oil (CO) as a renewable resource polyol and poly(ethylene glycol) (PEG) with tunable biodegradation rates as potential candidates for biomedical implants and tissue engineering were synthesized through the reaction of epoxy-terminated polyurethane prepolymers (EPUs) with 1,6-hexamethylene diamine curing agent. EPUs themselves were prepared from reaction of glycidol and isocyanate terminated polyurethane prepolymers made from CO or PEG and 1,6-hexamethylene diisocyanate. All of the polymers were characterized by conventional methods, and their physical, mechanical and viscoelastic properties were studied. The results showed that the degradation rate and mechanical properties of final products could be controlled by the ratio of PEG or CO based EPUs in the final products. Increasing the PEG based EPU content caused an increase in hydrolytic degradation rate and mechanical properties. Evaluation of the L-929 fibroblast cells' interaction with prepared polymeric films showed nontoxic behavior and good cytocompatibility.     

New potentially environmentally friendly copolymer of styrene and maleic acid—castor oil monoester

The maleic acid‐castor oil monoester (MACO) was synthesized and was used as monomer to synthesize a new potentially environmentally friendly copolymer of styrene and MACO (poly‐St/MACO) by suspension polymerization. Under the appropriate conditions, the poly‐St/MACO with yield of 81%, number average molecular weight of 44100 g/mol, and molecular weight distribution of 1.5 could be obtained. The chemical structures of the MACO and resulting copolymer were confirmed by Mass Spectrometry Infrared Spectroscopy and Nuclear Magnetic Resonance Spectroscopy H[1]. The results of thermogravimetric analysis and biodegradation test showed the poly‐St/MACO can be used as a new potentially environmentally friendly material with excellent thermal stability. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and characterization of novel poly(ester carbonate)s based on pentaerythritol

Novel poly(ester carbonate)s were synthesized by the ring‐opening polymerization of L ‐lactide and functionalized carbonate monomer 9‐phenyl‐2,4,8,10‐tetraoxaspiro[5,5]undecan‐3‐one derived from pentaerythritol with diethyl zinc as an initiator. ¹H NMR analysis revealed that the carbonate content in the copolymer was almost equal to that in the feed. DSC results indicated that T_g of the copolymer increased with increasing carbonate content in the copolymer. Moreover, the protecting benzylidene groups in the copolymer poly(L ‐lactide‐co‐9‐phenyl‐2,4,8,10‐tetraoxaspiro[5,5]undecan‐3‐one) were removed by hydrogenation with palladium hydroxide on activated charcoal as a catalyst to give a functional copolymer, poly(L ‐lactide‐co‐2,2‐dihydroxylmethyl‐propylene carbonate), containing pendant primary hydroxyl groups. Complete deprotection was confirmed by ¹H NMR and FTIR spectroscopy. The in vitro degradation rate of the deprotected copolymers was faster than that of the protected copolymers in the presence of proteinase K. The cell morphology and viability on a copolymer film evaluated with ECV‐304 cells showed that poly(ester carbonate)s derived from pentaerythritol are good biocompatible materials suitable for biomedical applications. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45:1737 –1745, 2007     

Synthesis and characterization of novel liquidcrystalline polyurethanes

Novel polyurethanes have been synthesized by the condensation of two rigid diols, biphenyl-4,4'-diol (BPH(4,4')D) and 4-hydroxyphenyl-4-hydroxybenzoate (4HPH4'HB), with the flexible hexamethylene diisocyanate (HDI). Their phase diagrams were established by means of differential scanning calorimetry, nuclear magnetic resonance and polarizing optical microscopy. Poly(4HPH4'HB/HDI) was found to display a nematic phase between 140 and 199°C; poly (BPH(4,4')D/HDI) also exhibits a mesomorphic phase, but so far the nature of this phase has not been established.     

Synthesis and shape memory behavior study of hyperbranched poly(urethane-tetrazole)

A novel hyperbranched poly(urethane-tetrazole)(HPUTZ) was synthesized via the A2+BB2' approach using hexadiisocyanate(HDI) and 3-(bis-(2-hydroxyethyl)) aminopropyltetrazole(HAPTZ).The molecular structure was characterized by FTIR and 1H NMR spectroscopy.The number average molecular weight was measured to be 1.05×104 g/mol with a polydispersity of 1.27 by GPC analysis.The HPUTZ was further cured by the semi-adduct(PEG-IPDI) from polyethylene glycol(PEG) reacting with isophorone diisocyanate(IPDI) to form th...     

Synthesis, characterization, degradation of biodegradable castor oil based polyesters

A new family of castor oil based biodegradable polyesters was synthesized by catalyst free melt condensation reaction between two different diacids and castor oil with d-mannitol. The polymers synthesized were characterized by NMR spectroscopy, FT-IR and the thermal properties were analysed by DSC. The results of DSC show that the polymer is rubbery in physiological conditions. The contact angle measurement and hydration test results indicate that the surface of the polymer is hydrophilic. The mechanical properties, evaluated in the tensile mode, shows that the polymer has characteristics of a soft material. In vitro degradation of polymer in PBS solution carried out at physiological conditions indicates that the degradation goes to completion within 21 days and it was also found that the rate of degradation can be tuned by varying the curing conditions.     

Synthesis and characterization of novel fluorinated poly(oxomolybdates)

Two novel poly(oxofluoromolybdate) clusters, [Mo6O18F6]6- and [Mo7O22F3]5-, have emerged from systematic field studies on the hydrothermal fluorination of poly(oxometalates). They are accessible via the hydrothermal treatment of Mo(VI)-based precursors in the presence of MF additives (M = Li, Na, Cs, NMe4). The new fluorinated polyanions are stabilized by specific alkali-cation combinations, and their packing motifs can be tuned through the careful choice of cations and synthetic parameters. The [Mo6O18F6]6- anion can be described as a cored and fluorinated form of the Anderson-Evans cluster type. It is stabilized by the interaction of two alkali cations with the fluorinated faces of the ring-shaped anion. The partial replacement of these capping alkali cations by the bulky, organic NMe4(+) cation leads to the formation of [Mo7O22F3](5-)-based compounds. Thus, the extent of fluorination can be controlled through the polarizability of the cationic environment: in the [Mo7O22F3]5- anion, half of the fluoride atoms of the [Mo6O18F6]6- anion are replaced by a capping MoO4 tetrahedron, thereby rendering this anion a fluorinated, lacunar derivative of the alpha-[Mo8O26]4- octamolybdate anion. All compounds have been structurally characterized by single-crystal X-ray diffraction and solid-state NMR spectroscopy. The templating role of the alkali cations is discussed and explained with the help of electrostatic calculations.     

Synthesis and properties of biodegradable elastomeric epoxy modified polyurethanes based on poly(ε-caprolactone) and poly(ethylene glycol)

Biodegradable polyurethane elastomers with potential for applications in medical implants with tunable degradation rate and physical properties were synthesized from reaction of epoxy terminated polyurethanes (EUP) with 1,6-hexamethylene diamine (HMDA) as curing agent. Poly(ε-caprolactone) (PCL) and poly(ethylene glycol) (PEG) as well as 1,6-hexamethylene diisocyanate (HDI) were used for preparation of isocyanate terminated polyurethanes which were subsequently blocked with glycidol to prepare EUPs. All materials were characterized by conventional methods, and their properties were studied fully. Results showed that elastomers based on PEG exhibit superior degradation rate and inferior mechanical properties in comparison to elastomers based on PCL. Optimum degradation rate and mechanical properties were obtained from elastomers made from mixture of PCL and PEG base EUPs.     

Synthesis and characterization of novel core-shell colloidal particles ZnO/poly(ethylcyanoacrylate)

Here we report the synthesis and physicochemical characterization of novel hybrid core/shell type ZnO/poly(ethylcyanoacrylate) colloidal particles. It is expected that coating ZnO colloidal particles with biocompatible and biodegradable poly(alkylcyanoacrylates) will pave the way toward the potential application of ZnO colloidal particles in biomedical research. Recent findings of cell selective toxicity indicate a potential utilization of ZnO colloidal particles in the treatment of cancer. For this purpose, ZnO colloidal particles have to be selectively delivered to the site of action by a suitable biocompatible and biodegradable carrier system. Toward this goal, poly(alkylcyanoacrylates) meet ideally the requirements for carrier systems in drug delivery due to their biocompatibility, biodegradability, low toxicity, and ability to overcome the multidrug resistance in cancer cells.     

Effect of the poly(oxytetramethylene)diol spacer length on some properties of liquid crystalline polyurethanes

Previous studies on liquid crystalline polyurethanes prepared from 4,4′-bis(2-hydroxyethoxy)biphenyl (BHBP) and 2,4-tolylene diisocyanate (TDI) were continued. In this article, a series of polyurethanes, which differ in the flexible spacer length and BHBP content is described. Poly(oxytetramethylene)diols of different molecular weights (PTMO, M _n = 250, 650, 1000, 2000) were used as flexible spacers. The polyurethanes were investigated by DSC, polarizing microscopy, x-ray diffractometry, and IR spectroscopy. The molecular weight distribution was determined by GPC. The morphology of the polyurethanes was investigated by the SALS method. Partial replacement of BHBP by 25–75 mol % PTMO and the flexible spacer length influence the liquid crystalline properties, the phase transition temperatures, and the range of mesophase occurrence. © 1993 John Wiley & Sons, Inc.     

Synthesis and characterization of novel biodegradable folate conjugated polyurethanes

In order to obtain targeting polyurethane micelle drug carriers, a series of biodegradable folate conjugated polyurethanes (FPUs) were synthesized using poly(ethylene glycol) (PEG) and poly(ε-caprolactone) (PCL) as soft segments, L-lysine ethyl ester diisocyanate (LDI) and 1,3-propanediol (PDO) as hard segments, and folic acid-ethylenediamine conjugate (FA-EDA) as an end-capping reagent. The resultant FPUs were fully characterized by (1)H NMR, Fourier-transform infrared (FTIR) spectroscopy, ultraviolet spectrophotometry (UV), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). These polymers can self-assemble into micelles in aqueous solutions confirmed by dynamic light scattering (DLS), pyrene fluorescence probe techniques, and transmission electron microscopy (TEM). The results indicated that the bulk structures and micellar properties of the prepared polyurethanes could be controlled by varying the PEG content in the soft segments. The present work provides a facile approach to prepare amphiphilic multiblock copolymers with tumor targeting moiety, which is a good candidate as biodegradable carriers for active intracellular drug delivery.     

In vitro degradation of poly(lactide-co-p-dioxanone)-based shape memory poly(urethane-urea)

The degradation of poly(lactide-co-p-dioxanone)-based shape memory poly(urethane-urea) (SMPU) in vitro was investigated by observing the changes of the pH value of incubation media, weight loss rate, molecular weight and scanning electron microscopy (SEM) during degradation duration of 12 weeks. Moreover, ¹H NMR was used to precisely study the degradation position by calculating the change of characteristic peaks value. The results revealed that the introduction of p-dioxanone (PDO) and -NH-(CO)- and -HN-(CO)-NH- would increase the hydrophilicity of polymer, so the degradation of SMPUs is higher than PDLLA control in the initial time, however, the degradation rate decreased in the anaphase of degradation, which can be attributed to the alkalic -NH₂ from the NH₂ and -NH-(CO), -NH-(CO)-NH-.     

蓖麻油与乳酸的共聚物合成与表征

用熔融聚合法合成了一种蓖麻油和乳酸的共聚物.以丁二酸酐作为共聚体系的引发剂和封端剂,制得端羧基共聚物P(LA-CO)-COOH.研究了反应条件对共聚物分子量的影响,通过核磁共振表征了共聚物的结构.DSC和TG研究表明,蓖麻油链段的引入破坏了聚乳酸的结晶性,提高了共聚物的热稳定性.     

Preparation and characterization of self-assembled nanoparticles formed by poly(ethylene oxide)-block-poly(epsilon-caprolactone) copolymers with long poly(epsilon-caprolactone) blocks in aqueous solutions

Aqueous solutions of self-assembled nanoparticles formed by biocompatible diblock copolymers of poly(epsilon-caprolactone)-block-poly(ethylene oxide) (PCL-PEO) with the same molar mass of the PEO block (5000 g mol-1) and three different molar masses of the PCL block (5000, 13 000, and 32 000 g mol-1) have been prepared by a fast mixing the copolymer solution in a mild selective solvent, tetrahydrofuran (THF)/water, with an excess of water, that is, by quenching the reversible micellization equilibrium, and a subsequent removal of THF by dialysis of the water-rich solution against water. The prepared nanoparticles have been characterized by static and dynamic light scattering and atomic force microscopy imaging. It was found that stable monodisperse nanoparticles are formed only if the initial mixed solvent contained 90 vol % THF. The results show that the prepared nanoparticles are spherical vesicles with relatively thick hydrophobic walls, that is, spherical core/shell nanoparticles with the hollow core filled with the solvent.     

Synthesis and characterization of an environmentally friendly PHBV/PEG copolymer network as a phase change material

Novel environmentally friendly poly(hydroxybutyrate-co-hydroxyvalerate) and poly(ethylene glycol) (PHBV/PEG) copolymer networks were synthesized through free-radical solution polymerization with PHBV diacrylate (PHBVDA) and polyethylene glycol diacrylate (PEGDA) as macromers. The molecular structure of PHBV/PEG copolymer network was characterized by Fourier transform infrared (FT-IR) and ¹H nuclear magnetic resonance (¹H NMR). The morphology of the PHBV/PEG copolymer network was characterized by polarization optical microscopy. Thermal energy storage properties, thermal reliability and thermal stability were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis. The results indicated that the PHBV/PEG copolymer network hindered the growth of PEG crystalline segments or PHBV segments. PHBV/PEG copolymer network had a higher latent heat enthalpy, which didn’t reduce with the components of PHBV increased. Moreover, PHBV/PEG copolymer network still had good thermal stability even at 300 °C. These results suggested that such environmentally friendly copolymer network would have wide applications in phase change energy storage materials.     

Synthesis and characterization of novel hyperbranched poly(imide silsesquioxane) membranes

A new family of hyperbranched polymers with chemical bonds between the hyperbranched polyimide and polysilsesquioxane network was synthesized by the reaction of an amine‐terminated aromatic hyperbranched polyimide with 3‐glycidoxypropyl trimethoxysilane, followed by hydrolysis and polycondensation in the presence of an acid catalyst. The hyperbranched poly(imide silsesquioxane) membranes were fabricated by the casting the aforementioned polymer solution onto a NaCl optical flat, which was followed by heating at 80 °C for 24 h. The membranes were characterized by Fourier transform infrared, X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, N₂ adsorption and desorption, and CO₂ adsorption and desorption. The presence of covalent bonds between the hyperbranched polyimide and polysilsesquioxane segments had a significant effect on the properties of the membranes. N₂ adsorption–desorption isotherms for these membranes showed surface areas of 6–16 m²/g, whereas CO₂ adsorption–desorption isotherms showed much higher surface areas in the range of 106–127 m²/g. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3736–3743, 2003     

Microgels based on isotactic poly(styrene): Synthesis and characterization

Poly(styrene) microgels are known, but the influence of tacticity on particle formation and behavior has not been investigated yet. Isotactic poly(styrene) (iPS) with M_n = 15–120 kg/mol is synthesized by coordinate polymerization and cross‐linked by Friedel–Crafts alkylation in a miniemulsion. Nuclear magnetic resonance (NMR) spectroscopy, light microscopy, cryogenic transmission electron microscopy, and wide‐angle powder diffraction are applied to understand the structure of microgels obtained. Typically, spherical microgels with overall diameter of 40–500 nm are found. Isotacticity of the polymer is retained during microgel formation. Increase of cross‐linker content leads to partial crystallinity inside the microgel. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 175–180     

Synthesis and characterization of novel polyurethanes,polypyridazine, and polyamide based on s-1,2,4,5-tetrazine

The synthesis and analysis of new polymeric materials based on 1,2,4,5-tetrazine are discussed in this study. Tetrazine was mixed with thermoplastic polyurethane in dimethylformamide (DMF) as solvent and dibutyl tin dilaurate as catalyst at 50°C for 24 h to create brush polyurethane-urea, which was then reacted with an unsaturated center in dimethyl sulfoxide as solvent at 60°C for 48 h made of either polyenol or thermoplastic polyurethane through π–π interaction. Because 1,2,4,5-tetrazine (red color) is known to act as an electron-deficient dine in inverse electron demand Diels–Alder reactions and can be easily converted to pyridazine (peach color) via [4 + 2] cycloaddition with suitable followed by expulsion of molecular nitrogen (cycloreversion), we observed a highly colored red shift to peach and this monitor for this reaction. Additionally, polyamide was prepared via reaction of 3,6-diamino-1,2,4,5-tetrazine with terephthaloyl chloride in DMF as a suitable solvent and triethylamine as basic catalyst at 0°C for 3 h and then 36 h at room temperature. The new polymers that were produced were elucidated by spectral data.     

Synthesis of star-shaped poly(epsilon-caprolactone) via'click' chemistry and 'supramolecular click' chemistry

The synthesis of star-shaped poly(epsilon-caprolactone) is described via azide-alkyne cycloaddition ('click' chemistry) and via self-assembly of polymeric ligands into [2 x 2] grid-like metal complexes ('supramolecular click' chemistry).