Poly(ester anhydride)s prepared by the insertion of ricinoleic acid into poly(sebacic acid)

New degradable poly(ester anhydride)s were prepared by the melt polycondensation of diacid oligomers of poly(sebacic acid) (PSA) transesterified with ricinoleic acid. The transesterification of PSA with ricinoleic acid to form oligomers was conducted via a melt bulk reaction between a high molecular weight PSA and ricinoleic acid. A systematic study on the synthesis, characterization, degradation in vitro, drug release, and stability of these polymers was performed. Polymers with weight‐average molecular weights of 2000–60,000 and melting temperatures of 24–77 °C were obtained for PSA containing 20–90% (w/w) ricinoleic acid. NMR and IR analyses indicated the formation of ester bonds along the polyanhydride backbone. These new degradable copolymers have potential use as drug carriers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1059–1069, 2003     

Synthesis and micellization of amphiphilic poly(sebacic anhydride)–poly(ethylene glycol)–poly(sebacic anhydride) block copolymers

Amphiphilic biodegradable block copolymers [poly(sebacic anhydride)–poly(ethylene glycol)–poly(sebacic anhydride)] were synthesized by the melt polycondensation of poly(ethylene glycol) and sebacic anhydride prepolymers. The chemical structure, crystalline nature, and phase behavior of the resulting copolymers were characterized with ¹H NMR, Fourier transform infrared, gel permeation chromatography, and differential scanning calorimetry. Microphase separation of the copolymers occurred, and the crystallinity of the poly(sebacic anhydride) (PSA) blocks diminished when the sebacic anhydride unit content in the copolymer was only 21.6%. ¹H NMR spectra carried out in CDCl₃ and D₂O were used to demonstrate the existence of hydrophobic PSA domains as the core of the micelle. In aqueous media, the copolymers formed micelles after precipitation from water‐miscible solvents. The effects on the micelle sizes due to the micelle preparation conditions, such as the organic phase, dropping rate of the polymer organic solution into the aqueous phase, and copolymer concentrations in the organic phase, were studied. There was an increase in the micelle size as the molecular weight of the PSA block was increased. The diameters of the copolymer micelles were also found to increase as the concentration of the copolymer dissolved in the organic phase was increased, and the dependence of the micelle diameters on the concentration of the copolymer varied with the copolymer composition. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1271–1278, 2006     

Laser light scattering study of the degradation of poly(sebacic anhydride) nanoparticles

Poly(sebacic anhydride) (PSA) is biocompatible and degradable in basic media. We micronized this water‐insoluble polymer into stable polymeric nanoparticles via a microphase inversion. Such PSA nanoparticles degraded much faster than bulk PSA. The influence of the surfactant, temperature, and pH on the degradation of the PSA nanoparticles was investigated by a combination of static and dynamic laser light scattering. Under each condition, the degradation rate was nearly constant up to a 75% weight loss; that is, the degradation was close to zero‐order. The degradation rate increased with the pH and temperature. Biomedical applications of such PSA nanoparticles are suggested. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 703–708, 2001     

Synthesis,characterization, and degradation of silicon(IV) phthalocyanines conjugated axially with poly(sebacic anhydride)

A novel silicon(IV) phthalocyanine with two axial poly(sebacic anhydride) chains has been synthesized by melt condensation of silicon phthalocyanine dihydroxide and oligo(sebacic anhydride). The polymer has been spectroscopically characterized and its molecular weights have been determined by gel permeation chromatography (GPC) and ¹H NMR spectroscopy. Nanoparticles with an intensity‐average apparent hydrodynamic radius of 65 ± 1 nm have been prepared from this polymer via a microphase inversion method with sodium dodecyl sulfate as the surfactant. The spherical nanoparticles contain loosely aggregated polymer chains, trapping about 90% of the water. On treatment with NaOH, these nanoparticles undergo degradation that has been monitored by laser light scattering and fluorescence spectroscopy. Because of the axial substitution, the change in the aggregation state of the phthalocyanine core of this polymer during nanoparticle formation and degradation is relatively small compared with that of the zinc(II) phthalocyanine analogue reported earlier, in which poly(sebacic anhydride) chains are linked to the periphery of the phthalocyanine ring. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 837–843, 2005     

聚酯／聚酸酐共混体系的降解和药物释放行为

聚酯／聚酸酐共混体系的降解和药物释放行为唐爱军，贺晓晖，李福绵（北京大学化学系北京１００８７１）关键词聚癸二酸，聚乳酸，聚己内酯，降解行为，药物释放行为聚酸酐，特别是脂肪类聚酸酥由于其化学价键的水解活泼性，是一类快速生物降解材料．由于聚酸团的水解机制...     

Degradable polymer blends. I. Screening of miscible polymers

Blends of biodegradable polymers having properties distinct from the individual polymer components, and that are suitable for use as carriers of pharmaceutically active agents, were prepared from two or more polyanhydrides, polyesters, and mixtures of polyanhydrides and low molecular weight polyesters. The blends have different properties than the original polymers, providing a mean for altering the characteristics of the polymeric matrix without altering the chemical structure of the component polymers. Aliphatic, aromatic, and copolymers of polyanhydrides were miscible in each other and formed less crystalline compositions with a single melting point which was lower than the melting point of the starting polymers. The polyesters: poly(lactide-glycolide), poly(caprolactone), and poly(hydroxybutyric acid) presented some miscibility in each other. However, the polyanhydrides were immiscible with the polyesters resulting in a complete phase separation both in solution or in melt mixing. Only low molecular weight polyesters (in the range of 2000) of lactide and glycolide, mandelic acid, propylenefumarate, and caprolactone presented some miscibility with polyanhydrides. Similarly, poly(orthoester) and hydroxybutyric acid polymers formed a uniform mixture with the anhydride polymers which had the two melting points of the original polymers. Drug release from polymer blends composed of poly(hydroxybutyric acid) or low molecular weight poly(lactic acid) with poly(sebacic anhydride) (PSA) showed a constant release of drug for periods from 2 weeks to several months as a function of the PSA content in the blend. Increasing the content of PSA, a fast degrading polymer, increases the release rate from the blend. © 1993 John Wiley & Sons, Inc.     

Synthesis and Characterization of New Functional Poly(ester-anhydride)s Based on Succinic and Sebacic Acids

Summary: New functional poly(ester-anhydride)s with allyl pendant groups in the side chains were obtained by polycondensation of sebacic acid (SBA) and poly(3-allyloxy-1,2-propylene succinate) (OSAGE) terminated with carboxyl groups. The carboxyl groups in OSAGE and in SBA were converted to mixed anhydride groups by acetylation with acetic anhydride. After that, prepolymers obtained were condensed in vacuum to yield higher molecular weight poly(ester-anhydride)s. The influence of SBA and OSAGE content in poly(ester-anhydride)s on their selected properties e.g. molecular weight, thermal and solubility characteristics as well as degradation rate and mode, were examined. Poly(ester-anhydride)s were degraded in aqueous buffer of pH 7.4 at 37 °C. The hydrolytic degradation was monitored by determination of weight loss of samples and by determination of ester to anhydride groups ratio.     

Tuning salicylate‐based polymers to overcome lag time and extend release via copolymers and polymer blends

This work describes how physicochemical properties of salicylate‐based poly(anhydride‐esters) (PAEs) can be tuned for drug delivery and optimized by comparing copolymerization with polymer blending. These alterations reduced the lag time of drug release, while still maintaining a long‐term drug release profile. The chemical composition of the copolymers and polymer blends was determined by proton nuclear magnetic resonance and additional properties such as molecular weight, glass transition temperature and contact angle measurements were obtained. In vitro salicylic acid release from the copolymers and blends is studied in an environment mimicking physiological conditions. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 685–689     

Synthesis of an esterase‐sensitive degradable polyester as facile drug carrier for cancer therapy

Polyethylene glycol (PEG) is widely used as a carrier to improve the pharmaceutical properties of drugs with low molecular weight. However, PEG has few functional groups (usually two) for drug conjugation and the resulting low drug content (1–2%) has hampered its clinical applications. For this study, we synthesized biodegradable poly(ethylene glycol‐co‐anhydride). This polyester‐based polymer possesses multiple carboxylic acid groups that can be used as facile drug carriers. Two anticancer drugs, camptothecin (CPT) and doxorubicin (DOX) were loaded into the carrier and their releasing properties and in vitro anticancer activities were studied. The polymer–drug conjugates exhibited esterase‐promoted degradation and drug release. Their cytotoxicity against the human ovarian cancer cell line SKOV‐3 was comparable to unconjugated drugs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 507–515     

Synthesis and characterization of a fluorinated polyanhydride

A fluorinated aromatic polyanhydride ( B ) was synthesized from the melt condensation of mixed anhydrides of 4,4′‐(hexafluoroisopropylidene)bis benzoic acid. Although the mixed anhydride from acetic anhydride yielded only a mixture of oligomers (weight‐average molecular weight < 2000), higher weight‐average molecular weight materials in the range of 15,000–18,000 were obtained with trifluoroacetic anhydride. Polymer B was soluble in chloroform and tetrahydrofuran, had a relatively high glass‐transition temperature of 176 °C with no melting point detected to 310 °C, and showed excellent thermal stability (5% weight loss observed at 380 °C by thermogravimetric analysis). The hydrolytic degradation of the fluorinated polyanhydride in a 0.1 M phosphate buffer of pH 7.4 at 37 °C was initially zero‐order, with 35% degradation occurring in 10 days. Loss of film integrity following that led to accelerated degradation, and almost complete dissolution was observed by the 16th day. The stability of the fluorinated polyanhydride in the solid state and in the solvent tetrahydrofuran was also evaluated. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3027–3036, 2002     

Polyanhydrides. I. Preparation of high molecular weight polyanhydrides

Polyanhydrides composed of the following diacids–sebacic acid, bis(p-carboxyphenoxy)propane, bis(p-carboxyphenoxy)hexane, isophthalic acid, 1,4-phenylene dipropionic acid, and dodecanedioic acid–were synthesized by a melt polycondensation process. Polymers of molecular weight up to 137,010 (weight average) and intrinsic viscosity of 0.92 dL/g were achieved. These high molecular weight polymers were reached by using pure isolated mixed anhydrides of diacids and acetic acid, under optimized reaction conditions (temperature of 180°C for 90 min under vacuum of 10^-4 mm Hg). Polymers of higher molecular weights were synthesized in shorter times by using heterogenic coordination catalysts: cadmium acetate, ZnEt₂-H₂O (1:1), barium oxide, calcium oxide, and calcium carbonate. By using these catalysts molecular weights of up to 245,000 were reached in 30 min of reaction. Films made of high molecular weight bis(p-carboxyphenoxy)propane–sebacic acid copolymers showed tensile strengths of 40–160 kg/cm²; the strength increased as a function of the bis(p-carboxyphenoxy)propane content and molecular weight.     

Synthesis and characterization of hyperbranched polyimides with good organosolubility and thermal properties based on a new triamine and conventional dianhydrides

A triamine monomer, 1,3,5‐tris(4‐aminophenoxy)benzene (TAPOB), was synthesized from phloroglucinol and 4‐chloronitrobenzene, and it was successfully polymerized into soluble hyperbranched polyimides (HB PIs) with commercially available dianhydrides: 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4′‐oxydiphthalic anhydride (ODPA), and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA). Different monomer addition methods and different monomer molar ratios resulted in HB PIs with amino or anhydride end groups. From ¹H NMR spectra, the degrees of branching of the amino‐terminated polymers were estimated to be 0.65, 0.62, and 0.67 for 6FDA–TAPOB, ODPA–TAPOB, and BTDA–TAPOB, respectively. All polymers showed good thermal properties with 10% weight‐loss temperatures (T₁₀'s) above 505 °C and glass‐transition temperatures (T_g's) of 208–282 °C for various dianhydrides. The anhydride‐terminated HB PIs showed lower T₁₀ and T_g values than their amino‐terminated counterparts. The chemical conversion of the terminal amino or anhydride groups of the 6FDA‐based polyimides into an aromatic imido structure improved their thermal stability, decreased their T_g, and improved their solubility. The HB PIs had moderate molecular weights with broad distributions. The 6FDA‐based HB PIs exhibited good solubility even in common low‐boiling‐point solvents such as chloroform, tetrahydrofuran, and acetone. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3804–3814, 2002     

Effect of PLGA block molecular weight on gelling temperature of PLGA‐PEG‐PLGA thermoresponsive copolymers

Thermoresponsive, biodegradable polymeric hydrogel networks are used widely in medicinal applications. Poly(d ,l ‐lactic acid‐co‐glycolic acid)‐b‐poly(ethylene glycol)‐b‐poly(d ,l ‐lactic acid‐co‐glycolic acid) (PLGA‐PEG‐PLGA) triblock copolymers exhibit a sol–gel transition upon heating. The effect of PLGA block and PEG chain molecular weights (MWs) on the gelling temperature of polymer aqueous solution (20% w/w) is described. All polymer solutions convert into a hard gel within 2 °C of the gelling temperature. The release properties of the gels were displayed using paracetamol as a representative drug. A linear relation is described between the gelling temperature and PLGA block MW. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 35–39     

Preparation and properties of molecular‐weight‐controlled polyimides derived from 1,4‐bis(4′‐amino‐2′‐trifluoromethylphenoxy)benzene and 4,4′‐oxydiphthalic anhydride

A series of molecular‐weight‐controlled fluorinated aromatic polyimides were synthesized through the polycondensation of a fluorinated aromatic diamine, 1,4‐bis(4′‐amino‐2′‐trifluoromethylphenoxy)benzene, with 4,4′‐oxydiphthalic anhydride in the presence of phthalic anhydride as the molecular‐weight‐controlling and end‐capping agent. Experimental results demonstrated that the resulting polyimides could melt at temperatures of 250–300 °C to give high flowing molten fluids, which were suitable for melt molding to give strong and flexible polyimide sheets. Moreover, the aromatic polyimides also showed good solubility both in polar aprotic solvents and in common solvents. Polyimide solutions with solid concentrations higher than 25 wt % could be prepared with relatively low viscosity and were stable in storage at the ambient temperature. High‐quality polyimide films could be prepared via the casting of the polyimide solutions onto glass plates, followed by baking at a relatively low temperature. The molten behaviors and organosolubility of the molecular‐weight‐controlled aromatic polyimides depended significantly on the polymer molecular weights. Both the melt‐molded polyimide sheets and the solution‐cast polymer films exhibited outstanding combined mechanical and thermal properties. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1997–2006, 2006     

Synthesis and characterization of biodegradable poly(L-aspartic acid-co-PEG)

The melt polycondensation reaction of the prepolymer prepared from N-(benzyloxycarbonyl)-L -aspartic acid anhydride (N-CBz-L -aspartic acid anhydride) and low molecular weight poly(ethylene glycol) (PEG) using titanium isopropoxide (TIP) as a catalyst produced the new biodegradable poly(L -aspartic acid-co-PEG). This new copolymer had pendant amine functional groups along the polymer backbone chain. The optimal reaction conditions for the preparation of the prepolymer were obtained by using a 0.12 mol % of p-toluenesulfonic acid with PEG 200 for 48 h. The weight-average molecular weight of the prepolymer increased from 1,290 to 31,700 upon melt polycondensation for 6 h at 130°C under vacuum using 0.5 wt % TIP as a catalyst. The synthesized monomer, prepolymer, and copolymer were characterized by FTIR, ¹H- and ¹³C-NMR, and UV spectrophotometers. Thermal properties of the prepolymer and the protected copolymer were measured by DSC. The glass transition temperature (T_g) of the prepolymer shifted to a significantly higher temperature with increasing molecular weight via melt polycondensation reaction, and no melting temperature was observed. The in vitro hydrolytic degradation of these poly(L -aspartic acid-co-PEG) was measured in terms of molecular weight loss at different times and pHs at 37°C. This pH-dependent molecular weight loss was due to a simple hydrolysis of the backbone ester linkages and was characterized by more rapid rates of hydrolysis at an alkaline pH. These new biodegradable poly(L -aspartic acid-co-PEG)s may have potential applications in the biomedical field. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2949–2959, 1998     

Palladium‐catalyzed three‐component coupling polycondensation of aromatic diiodide,aromatic bis(boronic acid propanediol ester), and norbornadiene: A new route for poly(p‐phenylene vinylene)

A novel synthetic method for soluble precursor polymers of poly(p‐phenylene vinylene) (PPV) derivatives by the palladium‐catalyzed three‐component coupling polycondensation of aromatic diiodides, aromatic bis(boronic acid) derivatives, and norbornadiene is described. For example, the polymerization of 1,4‐diiodo‐2,5‐dioctyloxybenzene, benzene‐1,4‐bis(boronic acid propanediol ester), and norbornadiene at 100 °C for 3 days provided a polymer consisting of the three monomer units in a 97% yield (number‐average molecular weight = 3100, weight‐average molecular weight/number‐average molecular weight = 1.37). A derivative of PPV was produced smoothly by the retro Diels–Alder reaction of the polymer both in a dodecyloxybenzene solution and in a film at 200 °C in vacuo. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3403–3410, 2005     

New water-soluble photo crosslinkable polymers based on modified poly(vinyl alcohol)

Poly(vinyl alcohol) (PVA) was partially modified by polymer analogous reaction with acrylic and methacrylic acid and with 2-vinyl-4,4-dimethyl-azlactone to obtain water-soluble polymers with pendant (meth)acrylate and acrylamide groups. Aqueous solutions of these polymers were crosslinked by UV-irradiation within seconds to form transparent networks with potential for use in contact lenses. The water content of these hydrogels was studied as a function of polymer molecular weight, the acetate, (meth)acrylate, and methacrylamide contents and irradiation conditions. The hydrogels showed good mechanical properties, even at low crosslinker (<5 mol %) and high water contents (60–80%). The formation kinetics and stability of aggregates, investigated by combined GPC/light-scattering measurements of samples annealed and/or stored at different temperatures (−20 to 100°C), give insight into PVA secondary structures. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 3603–3611, 1997     

Synthesis and properties of novel sulfonated polyimides containing 1,5‐naphthylene moieties

A series of novel sulfonated polyimides (equivalent weight per sulfonic acid = 310–744 g/equiv) containing 10–70 mol % 1,5‐naphthylene moieties were synthesized as potential electrolyte materials for high‐temperature polymer electrolyte fuel cells. The polycondensation of 1,4,5,8‐naphthalene tetracarboxylic dianhydride, 4,4′‐diamino‐2,2′‐biphenyldisulfonic acid, and 1,5‐diaminonaphthalene gave the title polymer electrolytes. The polyimide electrolytes were high‐molecular‐weight (number‐average molecular weight = 36.0–350.7 × 10³ and weight‐average molecular weight = 70.4–598.5 × 10³) and formed flexible and tough films. The thermal properties (decomposition temperature > 260 °C, no glass‐transition temperature), stability to oxidation, and water absorption were analyzed and compared with those of perfluorosulfonic acid polymers. The polyimide containing 20 mol % 1,5‐naphthylene moieties showed higher proton conductivity (0.3 S cm^?1) at 120 °C and 100% relative humidity than perfluorosulfonic acid polymers. The temperature and humidity dependence of the proton conductivity was examined. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3901–3907, 2003     

Synthesis and characterization of monomers and polymers for adhesives from methyl oleate

The focus of this work is to synthesize a monomer from a fatty acid methyl ester capable of forming high molecular weight polymers. The mono‐unsaturation in the starting material, methyl oleate, was first epoxidized using a peroxy acid. This intermediate material was further modified using acrylic acid. The acrylated molecule is able to participate in free‐radical polymerization reactions to form high molecular weight polymers. The rate of polymerization was low because of the long aliphatic structure of the monomer. It is hypothesized that the polymerization reaction occurred in the interface between the particle and water, thereby slowing down the reaction. After 18 h of reaction, a monomer conversion of approximately 91% was achieved. A maximum weight‐average molecular weight of approximately 10⁶ g/mol was observed after 14 h of reaction. At early reaction times linear polymers were formed. However, as the reaction time increased, the amount of branching that occurred on the polymer molecule increased, as indicated by gel permeation chromatography and light scattering. This has been attributed to chain transfer to polymer via hydrogen abstraction from a tertiary backbone C–H bond. The resulting polymer may be of considerable interest for pressure‐sensitive adhesive applications. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 451–458, 2002; DOI 10.1002/pola.10130     

Poly(lactic acid) brushes grow longer at lower temperatures

Poly(lactic acid) (PLA) brushes prepared by the ring opening of lactide were thicker when polymerized at a lower temperature (25 °C) than was typically used for polymerization in solution. The molecular weight of solution polymerized lactide was also higher when lactide was polymerized at 25 °C compared with polymerization at higher temperatures. However, the yield of PLA was low at this temperature. These results highlight the different requirements for solution polymerization and brush growth. In the former case, both percentage of conversion and molecular weight are important considerations. In the latter case, however, percentage of conversion is unimportant as a brush represents a very small amount of polymer. It was also shown during the course of these studies that the native hydroxy groups on silicon substrates and silanols in solution were equally good initiators when compared with hydroxy terminated self‐assembled monolayers on gold and alcohols, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3362–3367, 2010