Preparation of zinc-coordinated-DPA functionalized polyesters for gene condensation

Cationic polyesters have been widely utilized as efficient gene delivery carriers. Their ability in binding genes was majorly based on the electrostatic effect between the positive charges of polymers and the negatives charges of genes. It has been well known that large numbers of positive charges on the polymers would lead to undesired toxicity although strong gene binding capability. It was of great interest to developed a polymer with reduced positive charges while enhanced gene condensation ability. In this work, a library of polyesters functionalized by zinc-coordinated-dimethylpyridinium amine (DPA-Zn) have been successfully prepared by the polycondensation method starting from dimethyl 1,3-acetonedicarboxylate and 10 diols, followed by the post-modification using dimethylpyridinium amine and zinc nitrate. The post-modification efficiency was systemically evaluated and the optimized functionalization efficiency could reach around 50%. The gene condensation ability of the targeting polymers was also evaluated using gel retardation assay and dynamic light scatting. The results indicated that DPA-Zn functionalized polyesters could bind gene into nanocomplexes with the sizes around 200 nm.     

Hydroxyl‐functional polyurethanes and polyesters: synthesis,properties and potential biomedical application

This mini review gives an overview of the synthesis of polyurethanes and polyesters with pendant hydroxyl groups performed mainly in our group. Significant for the synthesis of most of these polymers with hydroxyl‐functional side groups is that no protection groups are needed. This is realised either by generating the OH group during polymer synthesis—demonstrated by the preparation of hydroxyl‐functional polyurethanes from dicarbonate monomers and diamines—or by using catalysts which discriminate between primary and secondary OH groups—demonstrated by the synthesis of hydroxyl‐functional polyesters based on malic acid using scandium triflate as catalyst. In addition, the potential of carbonate couplers for the synthesis of multifunctional polyurethane is presented. The application of such multifunctional polyurethanes as antimicrobial polymers and coatings is briefly discussed. Copyright © 2012 Society of Chemical Industry     

Study on hyperbranched polyesters as rheological modifier for Spandex spinning solution

The rheological behavior of polyurethane (PU)/N,N‐dimethylformamide (DMF) spinning solutions with various contents of hyperbranched polyesters was studied using a RS150L‐controlled stress rotational rheometer. The results showed that the viscosity of the spinning solutions could be greatly reduced by adding hyperbranched polyesters even at 0.5 wt% loading. The zero‐shear viscosity of solutions with hyperbranched polyesters was much lower than that of pure PU/DMF solution, which indicated a lower degree of entanglement when solutions were in a static state. The apparent activation energy of viscous flow and the critical shear rate for shear thinning of solutions with hyperbranched polyesters were much lower than that for pure PU/DMF solution, which indicated a weaker entanglement structure formed. In addition, the effect of hyperbranched polyesters on the mechanical properties of Spandex fiber was discussed. Copyright © 2006 Society of Chemical Industry     

Polyurethanes derived from caprolactone polyesters and diamines

Thermoplastic, light-stable polyurethanes have been prepared by the interfacial poly-condensation of secondary diamines with the bischloroformates of polyester diols derived from ε-caprolactones. A straight-line relationship was obtained from a logarithmic plot of inherent viscosity versus M _n. The effect of some structural variations on the properties of the polyurethanes is discussed. These variations included the molecular weight of the polyester diol, the initiator used in preparing the polyester diol, the introduction of a methyl substitutent on the caprolactone ring, and the structure of the diamine. Polyurethanes prepared from polyester diols of M _n from 2000–4000 are opaque, stiff materials which undergo a melting transition at 40–50°C. characteristic of the polyester component. Polyurethanes which are flexible and translucent at room temperature are obtained either by using a low molecular weight polyester diol or a copolyester diol containing > 25% methyl ε-caprolactone. The polyurethanes described are soluble in several common solvents and can be cold-drawn to produce material of high tensile strength. Thermal studies using DTA and TGA Show an exothermic reaction starting above 300°C. Rapid weight loss beginning at 300–330°C. and leveling off near 500°C. accounted for 85–90% of the total sample and is attributed to decomposition of the polyester Chains.     

Hydrogen bonding in blends of polyesters with dipeptide‐containing polyphosphazenes

New biomedically erodible polymer composites were investigated. Polyphosphazenes containing the dipeptide side groups alanyl–glycine ethyl ester, valinyl–glycine ethyl ester, and phenylalanyl–glycine ethyl ester were blended with poly(lactide‐co‐glycolide) (PLGA) with lactic to glycolic acid ratios of 50 : 50 [PLGA (50 : 50)] and 85 : 15 [PLGA (85 : 15)] with solution‐phase techniques. Each dipeptide ethyl ester side group contains two N? H protons that are capable of hydrogen bonding with the carbonyl functions of PLGA. Polyphosphazenes that contain only the dipeptide ethyl ester groups are insoluble in organic solvents and are thus unsuitable for solution‐phase composite formation. To ensure solubility during and after synthesis, cosubstituted polymers with both dipeptide ethyl ester and glycine or alanine ethyl ester side groups were used. Solution casting or electrospinning was used to fabricate polymer blend matrices with different ratios of polyphosphazene to polyester, and their miscibilities were estimated with differential scanning calorimetry and scanning electron microscopy techniques. Polyphosphazenes with alanyl–glycine ethyl ester side groups plus the second cosubstituent were completely miscible with PLGA (50 : 50) and PLGA (85 : 15) when processed via solution‐casting techniques. This suggests that the hydrogen‐bonding protons in alanyl–glycine ethyl ester have access to the oxygen atoms of the carbonyl units in PLGA. However, when the same pair of polymers was electrospun from solution, the polymers proved to be immiscible. Solution‐cast miscible polymer blends were obtained from PLGA (50 : 50) plus the polyphosphazene that was cosubstituted with valinyl–glycine ethyl ester and glycine ethyl ester side groups. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Biodegradable and temperature‐responsive thermoset polyesters with renewable monomers

A series of biodegradable thermoset polyesters, poly(1,8‐octanediol–glycerol–dodecanediaote)s (POGDAs), were synthesized with the polycondensation polymerization method without a catalyst and with different monomer molar ratios. Synthesis was confirmed with structural analysis via Fourier transform infrared spectroscopy. The effect of varying the monomer molar ratio on the material properties was illustrated in the gel content and swelling analysis, ultraviolet–visible spectroscopy, differential scanning calorimetry, X‐ray diffraction, and degradation tests. Degradation tests were performed in phosphate‐buffered solution at 37 °C for 60 days. Temperature‐responsive behavior was revealed with POGDA (0.5 glycerol), and bending tests were performed to study the shape‐memory effect. In vitro cytotoxicity tests and cell proliferation tests suggested that these POGDAs have potential applications in biomedical fields such as tissue engineering. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44007.     

Biomedical Polyurethanes for Anti-Cancer Drug Delivery Systems: A Brief,Comprehensive Review

With the intensive development of polymeric biomaterials in recent years, research using drug delivery systems (DDSs) has become an essential strategy for cancer therapy. Various DDSs are expected to have more advantages in anti-neoplastic effects, including easy preparation, high pharmacology efficiency, low toxicity, tumor-targeting ability, and high drug-controlled release. Polyurethanes (PUs) are a very important kind of polymers widely used in medicine, pharmacy, and biomaterial engineering. Biodegradable and non-biodegradable PUs are a significant group of these biomaterials. PUs can be synthesized by adequately selecting building blocks (a polyol, a di- or multi-isocyanate, and a chain extender) with suitable physicochemical and biological properties for applications in anti-cancer DDSs technology. Currently, there are few comprehensive reports on a summary of polyurethane DDSs (PU-DDSs) applied for tumor therapy. This study reviewed state-of-the-art PUs designed for anti-cancer PU-DDSs. We studied successful applications and prospects for further development of effective methods for obtaining PUs as biomaterials for oncology.     

Polyurethanes from benzene polyols synthesized from vegetable oils: Dependence of physical properties on structure

Asymmetric and symmetric aromatic triol isomers were synthesized from erucic acid. The pure asymmetric and symmetric triols were crosslinked with MDI into their corresponding polyurethane sheets. The physico‐chemical properties of these polyurethanes were studied by Fourier transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), thermogravimetric analysis coupled with Fourier transform infrared (TGA‐FTIR) spectroscopy, and tensile analysis. The A‐PU and S‐PU demonstrated differences in their glass transition temperatures (T_g) and crosslinking densities. The difference in T_g of these polyurethanes could be explained by the differences in crosslinking densities, which could be related to the increase in steric hindrance, to the crosslinking MDI molecules, between adjacent hydroxyl groups of the asymmetric triol monomers. Overall, it was found that both polyurethanes had similar mechanical and thermal properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Development of vegetable‐oil‐based polymers

The utilization of renewable resources for the preparation of new materials is an alternative option for reducing the high demand of fossil feedstocks. Vegetable oils are potential bioresources that are renewable and abundantly available. Triglyceride‐based vegetable oils, such as soybean, jatropha, linseed, sunflower, palm, castor, nahar seed, and canola oil, are being considered as precursors in the production of polymers. In this article, we attempt to summarize advancements in processes and technologies for the synthesis of polymers from various kinds of vegetable oils. The advantages and disadvantages of these biobased polymers with respect to traditional monomer‐based ones are also highlighted. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40787.     

Nondegradative microextrusion of resorbable polyesters for pharmaceutical and biomedical applications: The cases of poly‐lactic‐acid and poly‐caprolactone

In recent years biodegradable polymers, particularly polyesters such as the poly(lactic acid) (PLA) and polycaprolactone (PCL), have gained high interests for their applicability in the biomedical and pharmaceutical fields where they're used for manufacturing various different resorbable devices, from tissue engineering scaffolds to controlled drug release systems. Despite many positive characteristics, processability of these materials still remains a critical issue as they easily tend to degrade during manufacturing. In this article we aimed to assess microextrusion as a nondegradative process for manufacturing PLA and PCL. The results we experimentally obtained, that are hereby presented, set a new point in the on‐going debate on degradation during processing of resorbable polymers as they allow to affirm that microextrusion leaves unmodified molecular weight distributions without producing any evident reductions in mean molecular weight. Microextrusion thus represents a risk‐free high molecular weight polymer processing solution for obtaining nondegraded products within pharmaceutical and biomedical production lines, such as for scaffolds for tissue engineering applications or drug delivery. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Water‐blown polyurethane/polyisocyanurate foams made from recycled polyethylene terephthalate and liquefied wood‐based polyester polyol

Depolymerized polyethylene terephthalate and liquefied wood polyesters can be used as a polyol for the production of polyurethane/polyisocyanurate foams. In this research, liquefied wood was synthesized by using a combination of diethylene glycol and glycerol and due to the possibility of using glycerol that is a by‐product in biodiesel production, our goal was to use as much glycerol in the liquefaction reagent as possible. We determined the properties of the polyols, properties of produced foams, and explained their correlation. Greater amount of glycerol in the liquefaction reagent resulted in higher OH number, molecular weight, functionality, and viscosity of the polyol, as well as in longer cream time and tack free time in foam preparation. Glass transition temperature, density, and water absorption of the foam increased with increasing amount of glycerol in liquefied wood. Compressive stress increased up to 30% of the glycerol in the reagent and then reduced, while thermal conductivity was not affected. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41522.     

Regular network polyesters from benzenepolycarboxylic acids and glycol

Regular network polyesters were prepared from trimesic (Y), pyromellitic (X) or mellitic (Y_H) acids and 1,6-hexanediol (6G). Prepolymers prepared by melt-polycondensation were cast from dimethylformamide solution and post-polymerized at 260°C for various times to form a network. The resultant films were transparent, flexible and insoluble in organic solvents. Degrees of reaction estimated from the infra-red absorbance of ester and methylene groups were 95, 95 and 96% for 6GY, 6GX and 6GY_H post-polymerized for 12 h, respectively. X-ray diffraction intensity curves showed the formation of some ordered structure owing to the regular networks, and the degrees of ordering were 6GY> 6GX> 6GY_H. Densities were 1.227, 1.290 and 1.289 g cm⁻³ and heat distortion temperatures measured by thermomechanical analysis were 75, 72 and 75°C for 6GY, 6GX and 6GY_H post-polymerized for 12 h, respectively. Tensile strengths were in the order 6GY> 6GX> 6GY_H and Young's moduli were 6GY_H = 6GX> 6GY. Dye absorptions were 6GX> 6GY> 6GY_H, and water absorptions and weight losses in alkali solution were 6GY_H > 6GX> 6GY. These effects of the number of functional groups on the benzene ring on the structure and properties were discussed, and compared with those of previously reported network polymers.     

Polyurethanes derived from carbohydrates and cystine‐based monomers

Linear [m,n]‐type polyurethanes (PUs) fully based on renewable materials are synthesized by interfacial polycondensation reaction of diamines derived from the amino‐acid cystine with (bis)chloroformates derived from alditols having L‐arabino or xylo configuration. The degradability of the new PUs has been enhanced by the introduction of disulfide linkages into the polymer backbone leading to a new group of stimulus‐responsive sugar‐based polyurethanes able to be degraded by glutathione under physiological conditions. All these polyurethanes are stable up to around 245°C, decomposing at higher temperatures through a one‐stage mechanism. The new materials display high chemical homogeneity and degradability in both hydrolytic and reductive environments, with reductions of above 90% in M_w. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41304.     

Polyurethane foams from alkaline lignin‐based polyether polyol

As a byproduct produced during biorefining, alkaline lignin (AL) possesses multiple benzene ring and phenol hydroxyl groups with high chemical reactivity, and is renewable and cheaper than petrochemical products. Here, AL was liquefied in polyethylene glycol‐400/glycerol and subsequently used to prepare polyurethane foams (PUFs). The results showed that the AL could be almost completely liquefied. The resulting lignin‐based polyether polyol (LPP) exhibited physicochemical properties similar to a commercial polyether polyol (PP). The PUFs made from LPP presented better thermal stability and higher compressive strength than those PUFs obtained from commercial PP, suggesting this could be a viable commercial application for AL. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43261.     

Environmental degradation of biodegradable polyesters. IV. The effects of pores and surface hydrophilicity on the biodegradation of poly(ϵ‐caprolactone) and poly[(R)‐3‐hydroxybutyrate] films in controlled seawater

Poly(?‐caprolactone) (PCL) and poly[(R)‐3‐hydroxybutyrate] (R‐PHB) films with pores and hydrophilic surfaces were prepared by the water extraction of poly(ethylene oxide) from as‐cast blend films (1:1) and by the alkali treatment of as‐cast nonporous films, respectively. These films, as well as as‐cast nonporous PCL and R‐PHB films, were biodegraded in static seawater kept at 25°C, and their biodegradation was monitored with gravimetry, gel permeation chromatography (GPC), and scanning electron microscopy. The pores or highly hydrophilic surfaces of the PCL and R‐PHB films enhanced their biodegradation in seawater. Moreover, GPC measurements could be used to trace the biodegradation in seawater when the biodegradation proceeded to a great extent. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 587–593, 2003     

Polyesters from lignin. 1. The reaction of kraft lignin with dicarboxylic acid chlorides

Kraft lignin was treated with dicarboxylic aliphatic (sebacoyl) or aromatic (terephthaloyl) acid chlorides in N,N-dimethylacetamide or N-methyl-2-pyrrolidone as solvents in the presence of triethylamine or pyridine as catalysts. The polyester gels obtained were characterized by IR after specific extractions and the chemical incorporation of lignin was proved unambiguously. Their thermal behaviour was determined by DSC and TGA; they are amorphous and stable up to 200°C in a nitrogen atmosphere. The reactivities of the two types of hydroxyl group (aliphatic and phenolic) were assessed from model reactions carried out in the same conditions.     

Synthesis of L-Lactide-Based Segmented Polyurethanes

A series of segmented polyurethanes with polylactidediols soft segments and methylene-diphenyl-diisocyanate/1,4-butanediol hard segments with molecular weights in the range of 6.18 × 10³ to 9.36 × 10³ Da were synthesized. Stannous octoate was the catalyst for the reactions. These polymers were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, gel permeation chromatography, and thermogravimetric analyzer. Fourier transform infrared analyses revealed the formation of urethane groups and complete curing of polyurethane. The thermal degradation temperatures were in the range of 248.55–257.09°C. X-ray diffraction studies confirmed the segmented structure of polyurethanes.     

UV固化水性聚氨酯概述及最新研究进展

在水性聚氨酯的制备过程中引入UV固化技术,可以得到性能优良的水性聚氨酯材料。本文阐述了UV固化水性聚氨酯的制备过程及最新研究进展,并展望了这一领域今后的发展趋势。     

Viscosity behavior of hydroxylated and acetoacetylated polyesters

Viscosity studies on polyester polymers are important for governing their processing characteristics before their industrial application. In this study, the viscosity properties of hydroxylated polyesters with different diols and partially acetoacetylated polyesters with different amounts of ethyl acetoacetate were examined. The melt viscosities of these polymers were measured with different shear rates and at varying temperatures. The results were analyzed with the Williams–Landel–Ferry equation. In high‐solid‐coatings applications, an understanding about the surface properties and thermodynamic quantities, such as cohesive energy density, the solubility parameter, and the Flory–Huggins interaction parameter, are important. To evaluate these quantities, an atomistic simulation methodology based on Accelrys software was used, which provided insights into the structures of these compounds for further applications. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2422–2435, 2006