Encapsulation of curcumin by methoxy poly(ethylene glycol‐b‐aromatic anhydride) micelles

Suitable carrier systems for sustained release of curcumin were studied by using the self‐assembled polymeric micelles. Poly(ethylene glycol) methyl ether and poly(aromatic anhydride) were used as the hydrophilic and hydrophobic blocks, respectively, in forming amphiphilic diblock copolymers. Four different types of polymers methoxy poly(ethylene glycol‐ b‐1,3‐bis(p‐carboxyphenoxy)propane) (mPEG₅₀₀₀CPP, mPEG₂₀₀₀CPP), methoxy poly(ethylene glycol‐b‐1,6‐bis(p‐carboxyphenoxy)hexane) (mPEG₅₀₀₀CPH, mPEG₂₀₀₀CPH) were synthesized via melt condensation approach. Micelles were formed at very low polymer concentration with stable hydrophobic cores. The particle sizes of micelles remained stable during degradation period. All four different polymeric micelles showed low cytotoxicity toward human fibroblasts cells and can kill cancer cells in very low concentrations. High loading efficiency and drug content were observed in curcumin‐loaded micelles. Curcumin showed mild initial burst (30% of drug loading in the first 24 h) when released from the micelles and its release was sustained for at least 18 days. These micelles, especially those of mPEG₅₀₀₀CPP, show potential to serve as the delivery vehicles for sustained release of curcumin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Kinetics of drug release from drug carrier of polymer/TiO2 nanotubes composite—pH dependent study

This study was to investigate the kinetics of drug release from polymer/TiO₂ nanotubes composite. Lidocaine and carprofen were selected as model drugs to represent weak base and weak acid drugs, respectively. Mathematical models used to fit the in vitro drug release experimental data indicate that at higher pH, the drug release was first order diffusion controlled. At lower pH, the release of the two drugs exhibits two staged controlled release mechanism. The first phase is due to drug diffusion and the second stage is a result of poly(lactic‐co‐glycolic acid) (PLGA) polymer degradation. The rate of drug release from polymer/TiO₂ nanotubes drug carrier was mainly controlled by three pH dependent factors: the solubility of the drug, the degree of polymer swelling/degradation, and the electrostatic force between polymer and drug. This study suggests that controlled release could be achieved for polymer/TiO₂ nanotubes drug carrier via the modulation of pK_a values of polymers and drug solubility. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41570.     

Polyanhydrides: the effects of ring substitution changes on polymer properties

Summary We synthesized polymers that overcome the processing problems associated with aromatic polyanhydrides. In this paper, we focus on the synthesis and characterization of ortho-substituted polyanhydrides, poly[1,3-bis(o-carboxyphenoxy)propane anhydride] (o-CPP) and poly[1,6-bis(o-carboxyphenoxy)hexane anhydride] (p-CPH). By lengthening the alkyl chain between aryl groups (from propane to hexane) and changing the ring substitution pattern from para- to ortho-, we observed enhanced solubility of aromatic polyanhydrides. Ultimately, these polyanhydrides may be useful as polymer scaffolds for use as functional soft tissue substitutes. Received: 29 July 1998/Revised version: 3 November 1998/Accepted: 6 November 1998     

Synthesis and characterization of the environmental‐sensitive hyperbranched polymers as novel carriers for controlled drug release

Novel hyperbranched polymers, which contain a hydrophobic branched poly(p‐(chloromethy)styrene) (PCMS) core and poly(N,N‐dimethylaminoethyl methacrylate) (PDMA) shell that exhibited environmental sensitivity, have been synthesized by atom transfer radical polymerization (ATRP). At first, a hyperbranched polymer (PCMS) core is obtained via ATRP of p‐(chloromethy)styrene (CMS), which may act as an “inimer”‐monomer and initiator. Then the modified hyperbranched polymers having different average arm length consisting of PCMS and PDMA are synthesized by ATRP using anterior PCMS as macroinitiators. Their macromolecular structures are characterized by FTIR and ¹H NMR. Using chlorambucil as a model drug, the behaviors of the controlled drug release from the environmental‐sensitive hyperbranched polymers with different average chain length of PDMA and degree of branching are studied. The data demonstrate that the rate of the drug release can be effectively controlled by pH value, and these environmental‐sensitive hyperbranched polymers have the potential to be used as novel carriers in some controlled drug release systems in the future. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 311–316, 2006     

Nitro derivatives of PEEK‐WC

Nitrated poly(oxa‐p‐phenylene‐3,3‐phthalido‐p‐phenylene‐oxa‐p‐phenylene‐ oxy‐phenylene) (PEEK‐WC) with various average degrees of substitution was obtained by reaction with several nitrating agents. By working under controlled reaction conditions, little degradation of the parent polymer is observed. The nitro derivatives of PEEK‐WC show a high thermal stability, and are able to form membranes by means of phase inversion technique. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1037–1045, 2001     

Preparation,characterization and degradation characteristics of polyanhydrides containing poly(ethylene glycol)

Poly(ethylene glycol) (PEG) segments were introduced into a polyanhydride main chain by copolymerization of terminal-carboxylated poly(ethylene glycol) with diacidic monomers (sebacic acid and trimellitylimidoglycine). IR and ¹H NMR spectroscopy confirmed the copolymer structures. DSC analysis showed that these polyanhydrides have low T_g and low crystallinity. In vitro degradation tests indicated that introducing PEG segments accelerated the degradation rate of these polymers and the degradation duration could be manipulated from 3 days to 3 weeks. The pH of the environment caused by the polymer degradation was lower than 5.0; therefore, the polyanhydrides could be used as components of a newly designed pulsed-release device for peptide and protein delivery. © 1999 Society of Chemical Industry     

Cross-linked amino acid-containing polyanhydrides for controlled drug release applications

Cross-linked amino acid-containing polyanhydrides based on N-trimellitylimido-β-alanine (TMA-ala) or N-trimellitylimido-glycine (TMA-gly) and sebacic acid (SA) were synthesized by copolycondensation using 1,3,5-benzenetricarboxylic acid (BTC) prepolymer as a cross-linking agent. Differential scanning calorimetric (DSC) studies of the insoluble copolymers revealed only one sharp melting transition, indicating their cross-linked and/or randomly copolymeric structure. These cross-linked polymers can degrade completely into water-soluble molecules such as amino acids and natural fatty acid, which can be further metabolized by the body. This is an improvement over the photo-cross-linked polyanhydrides reported in the literature, whose cross-links hydrolyze to poly(methacrylic acid), a non-degradable and non-metabolizable macromolecule with limited biocompatibility. The cross-linked polymers were mixed with p-nitroaniline (PNA) and compressed into discs. In vitro degradation and solute release into physiological media were quantified for up to 70 h. Results showed that, relative to their linear counterparts, cross-linking has little effect on the degradation and solute release of these specific polymers.     

Synthesis and characterization of new biodegradable fluorescing poly(amide‐anhydrides)

Biodegradable/alternate/poly(amide‐anhydrides), [? C(O)PhNHC(O)(CH₂) _nC(O)O? ] _x, were synthesized by melt polycondensation, where n was 2, 3 or 4. The polymers have been characterized by NMR, DSC, wide‐angle X‐ray diffractometry and fluorometry. All the polymers are amorphous and their T_g ranges from 60 to 80 °C. Poly(p‐(carboxyethylformamido)benzoic anhydride) (PCEFB) as a film or in solution in chloroform can emit strong fluorescence, which was not observed for the other two polyanhydrides (n = 3, 4). The maximum emission wavelength varies with the excitation wavelength, 480 and 520 nm at the excitation wavelength of 470 nm, and 430 nm at 356 nm. In addition, the fluorescence intensities increase linearly with the molecular weight of PCEFB. Such inherent fluorescing properties of PCEFB, together with its biodegradability, make the polymer a potential visible matrix for drug delivery. © 2001 Society of Chemical Industry     

Synthesis,characterization, and photophysical properties of novel poly(p‐phenylene vinylene) derivatives with conjugated thiophene as side chains

Two novel poly(p‐phenylene vinylene) (PPV) derivatives with conjugated thiophene side chains, P1 and P2, were synthesized by Wittig‐Horner reaction. The resulting polymers were characterized by ¹H‐NMR, FTIR, GPC, DSC, TGA, UV–Vis absorption spectroscopy and cyclic voltammetry (CV). The polymers exhibited good thermal stability and film‐forming ability. The absorption spectra of P1 and P2 showed broader absorption band from 300 to 580 nm compared with poly[(p‐phenylene vinylene)‐alt‐(2‐methoxy‐5‐octyloxy‐p‐phenylene vinylene)] (P3) without conjugated thiophene side chains. Cyclic voltammograms displayed that the bandgap was reduced effectively by attaching conjugated thiophene side chains. This kind of polymer appears to be interesting candidates for solar‐cell applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Photolysis of poly(benzyl methacrylate)s and poly(benzyl acrylate)s in solution and films

Methacrylate and acrylate copolymers containing benzyl or 1‐phenylethyl groups and their monomeric model compounds were irradiated with a 254‐nm light in CH₂Cl₂ and solid films. Low molecular weight and polymeric products were analyzed by gas chromatography (GC) and NMR spectroscopy, respectively, and main‐chain scission efficiencies were determined by gel permeation chromatography (GPC). The results indicate that the ester bond cleavage in the side chain produces alkyl radicals in the main chain, leading to main‐chain scission and crosslinking. The higher stability of tertiary alkyl radicals formed in methacrylate polymers lead to the predominant main‐chain scission in solution. On the other hand, acrylate polymers were less susceptible to photodegradation. The degradabilities of the polymer films reflected those of the polymer solutions, although crosslinking preferentially occurred. The distinct effect of oxygen on the degradation was also observed in solution and films. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2227–2236, 2001     

Structural and mechanical characterization of poly(ether ether ketone) (PEEK) and sulfonated PEEK films: Effects of thermal history,sulfonation, and preparation conditions

In this work, virgin and sulfonated poly(ether ether ketone) films (PEEK and SPEEK, respectively) have been studied by dynamic mechanical analysis, modulated differential scanning calorimetry, wide‐angle X‐ray diffraction, birefringence, and optical microscopy. The properties of the unmodified polymer have been addressed to assess the original morphological characteristics and the changes induced by sulfonation. In general, the introduction of ionic groups in the polymer backbone alters dramatically the intrinsic properties of the parent material. The particular thermomechanical response exhibited by PEEK and SPEEK samples, characterized by a hysteresis loop, can be explained by the reversible and irreversible relaxation–orientation of the microstructure, even in the sub‐T_g region. The results showed that the preparation conditions largely determine the nonequilibrium morphological features of both compression‐molded PEEK films and solvent‐cast SPEEK membranes. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 756–774, 2006     

Polymeric coatings for photostability enhancement of poly(p‐phenylene vinylene) derivative films

Poly(p‐phenylene vinylene) (PPV) derivatives are an important class of conjugated polymers, known for their applications as electroluminescent materials for light‐emitting devices and sensors. These derivatives are highly susceptible to photodegradation by the combined action of oxygen and light. Here, the use of various commercial polymers as protective coatings against the photodegradation of PPV derivatives was explored. Cast films of two similar PPV derivatives, poly[(2‐methoxy‐5‐n‐hexyloxy)‐p‐phenylene vinylene] and poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐p‐phenylene vinylene], were submitted to photodegradation by exposure to white light under atmospheric conditions in order to verify if the type of side chain (linear or branched) had an effect on the photodegradation. No significant differences in the photodegradation behaviour between the two polymers were noticed. The following commercial polymers were tested as protective coatings for the PPV derivative cast films: 99 and 80% hydrolysed poly(vinyl alcohol) (PVA) and starch. The best results were achieved using coatings of 99% hydrolysed PVA, which increased about 700 times the time necessary for complete degradation of the PPV derivative films. The results show the effectiveness of this coating in minimizing and, possibly, controlling the effects of the photodegradation of PPV derivative films, which can be useful in many applications, e.g. oxygen sensors. Copyright © 2009 Society of Chemical Industry     

Increase of photoluminescence from fullerene‐doped polymers under laser irradiation

Photoluminescence (PL) from fullerene (C₆₀ and C₇₀)‐doped polymers such as poly(methyl methacrylate) (PMMA), polystyrene (PS), poly(methyl phenyl silane) (PMPS) and poly(phenyl silsesquioxane) (PPSQ) increases gradually under laser irradiation in air (but not in vacuum and in nitrogen) and eventually becomes visible to the naked eye. Concomitantly, the PL peak is broadened and, in most cases, blue‐shifted. No such PL increases are observed for pure C₆₀ films made by vacuum vapor deposition and pure polymer films. Among the polymers used, fullerene‐doped PMMA has the greatest PL increase after several hours of laser irradiation and fullerene‐doped PMPS has the highest rate of PL increase at the initial stage of the laser irradiation. To gain an insight into the mechanism of the PL increase, laser‐irradiated fullerene‐doped PMMA samples were analyzed by UV‐Vis spectrophotometer, FT‐IR, mass spectrometry, GPC and NMR. The results show that the PL increase can be attributed to CH₆₀O_n‐polymer (or C₇₀O_n‐polymer) and oxidized fullerene‐polymer adducts formed by some laser‐induced photochemical reactions among fullerenes, oxygen and polymers.     

Barrier properties of blends based on liquid crystalline polymers and polyethylene

Blends of an extrusion‐grade polyethylene and two different liquid crystalline polymers of Vectra type were prepared by melt mixing using poly(ethylene‐comethacrylic acid) as compatibilizer. Oxygen and water vapor permeability, transparency and welding strength of compression molded and film blown specimens were studied. The compression molded blends showed gas permeabilities conforming to the Maxwell equation assuming low permeability liquid crystalline polymer spheres in a high permeability polyethylene matrix. One of the liquid crystalline polymers with suitable rheological properties formed a more continuous phase in the film blown blends and a substantial decrease in oxygen and water vapor permeability was observed in these blends. The compression molded blends with 50% liquid crystalline polymer and some of blow molded blends showed very high gas permeabilities. It is believed that voids forming continuous paths through the structure were present in these samples. The blends showed significantly higher opacity than pure polyethylene.     

Preparation and characterization of binary blends composed of poly(dioctylfluorene‐alt‐hexylsulfonylthiophene) and nonconjugated polymers

The solutions and the thin films of poly[9,9‐dioctyl‐2,7‐fluorene‐alt‐2,5–(3‐hexyl‐sulfonylthiophene)] (PFSO₂T) and its binary blends with other nonconjugated polymers such as poly(methyl methacrylate) (PMMA), polycarbonate (PC), and ethylene vinyl acetate copolymer (EVA) can be prepared by different concentrations from a polymer solution. Binary polymer blends can increase the absorbance and photoluminescence intensities in the solid state due to nonconjugated polymers can act as dispersion agents which can reduce the interchain interaction or the aggregation of the conjugated polymers. Photoluminescence intensity of the thin films of fluorescent polymers blending with ethylene vinyl acetate copolymers exhibited six times higher than that of the neat fluorescent polymers. The PFSO₂T/EVA binary blends reveal the least extent of optical degradation of around 20% compared to those binary blends in both absorption and emission intensities after the irradiation under the UV‐light for 20 h. The cross‐sectional morphology of fluorescent polymers blending with ethylene vinyl acetate copolymers reveals little aggregation and better phase separation among the other binary polymer blends. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44969.     

Surface modification of LDPE with PE‐PEO graft copolymer

Films of LDPE containing 1–10 wt % of various polymeric additives were prepared by different techniques. Three poly(ethylene‐graft‐ethylene oxide)s synthesized by grafting poly(ethylene‐co‐acrylic acid) with poly(ethylene oxide) monomethyl ether (MPEO), and two pure MPEOs having molecular weights 750 and 2000 were used as additives. The additives were mixed with LDPE both by blending in a common solvent and by melt mixing. The blends were then solvent cast from xylene onto glass Petri dishes or compression molded between glass plates. The film surfaces were studied by water contact angle measurements and by X‐ray photoelectron spectroscopy (XPS), and melting points and heats of melting were recorded by differential scanning calorimetry (DSC). The blends had a two‐phase morphology, with enrichment of the graft copolymers at the glass–polymer interface, as shown by contact angle values and XPS spectra. Large differences in the interface accumulation between the different film samples were observed. Films prepared by compression molding of solution‐mixed blends exhibited much lower surface accumulation of graft copolymer at the glass–polymer interface than did the solvent cast or melt‐mixed/compression‐molded samples. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 316–326, 2000     

Synthesis and characterization of p‐perfluoro{1‐[2‐(2‐fluorosulfonyl‐ethoxy)propoxy]}ethylated poly(α‐methyl styrene)

p‐Perfluoro{1‐[2‐(2‐fluorosulfonyl‐ethoxy)propoxy]}ethylated poly(α‐ methyl styrene) 3 was synthesized via electron transfer of perfluoro‐di{2‐[2‐(2‐fluorosulfonyl‐ethoxy)propoxy]}propionyl peroxide 2 and poly(α‐methyl styrene) 1 at different reactant molar ratios (2 : 1). The modified polymer 3 was characterized by various techniques. The ring p‐substitution was proved by FTIR and ¹⁹FNMR. The desulfonation appeared at above 124°C was found by TGA. The molecular weight determined by GPC increased with the increase of reactant molar ratio, and the polydispersity values indicated there was no degradation of the parent polymer chain in the reaction. Followed by hydrolysis and acidification, the modified polymer 3 could be further quantitatively converted into its sulfonic form 4. Ion exchange capacity of novel polyelectrolyte 4 can be controlled by changing reactant molar ratio (2 : 1). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3615–3618, 2006     

Hydrolytic degradation and crystallization behavior of linear 2‐armed and star‐shaped 4‐armed poly(l‐lactide)s: Effects of branching architecture and crystallinity

“Linear” aliphatic polyesters composed of two poly(l ‐lactide) arms attached to 1,3‐propanediol and “star‐shaped” ones composed of four poly(l ‐lactide) arms attached to pentaerythritol (2‐L and 4‐L polymers, respectively) with number‐average molecular weight (M_n) = 1.4–8.4 × 10⁴g/mol were hydrolytically degraded at 37°C and pH = 7.4. The effects of the branching architecture and crystallinity on the hydrolytic degradation and crystalline morphology change were investigated. The degradation mechanism of initially amorphous and crystallized 2‐L polymers changed from bulk degradation to surface degradation with decreasing initial M_n; in contrast, initially crystallized higher molecular weight 4‐L polymer degraded via bulk degradation, while the degradation mechanism of other 4‐L polymers could not be determined. The hydrolytic‐degradation rates monitored by molecular‐weight decreases decreased significantly with increasing branch architecture and/or higher number of hydroxyl groups per unit mass. The hydrolytic degradation rate determined from the molecular weight decrease was higher for initially crystallized samples than for initially amorphous samples; however, that of 2‐L polymers monitored by weight loss was larger for initially amorphous samples than for initially crystallized samples. Initially amorphous 2‐L polymers with an M_n below 3.5 × 10⁴g/mol crystallized during hydrolytic degradation. In contrast, the branching architecture disturbed crystallization of initially amorphous 4‐L polymers during hydrolytic degradation. All initially crystallized 2‐L and 4‐L polymers had δ‐form crystallites before hydrolytic degradation, which did not change during hydrolytic degradation. During hydrolytic degradation, the glass transition temperatures of initially amorphous and crystallized 2‐L and 4‐L polymers and the cold crystallization temperatures of initially amorphous 2‐L and 4‐L polymers showed similar changes to those reported for 1‐armed poly(l ‐lactide). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41983.     

Controlled dispersion of a porphyrin/fullerene donor‐acceptor complex in semiconducting polymer thin films: Intermolecular interactions of polymers with porphyrin and fullerene

Thin films composed of semiconducting polymers [poly(2‐vinyl naphthalene), poly(4‐diphenyl aminostyrene), poly(1‐vinyl pyrene), and poly(3‐hexyl thiophene‐2,5‐diyl)], zinc(II)?5,10,15,20‐tetra‐(2‐naphthyl)porphyrin, and [6,6]‐phenyl‐C₆₁‐butyric acid methyl ester blends were prepared to investigate the controlled dispersion of porphyrin molecules in semiconducting polymer thin films. Tailoring the intermolecular interactions between the polymer/fullerene, polymer/porphyrin, and porphyrin/fullerene systems was found to be an effective method of controlling the dispersion. When the polymer/porphyrin interactions were enhanced, intermixed porphyrin/fullerene donor–acceptor complex domains were formed, whereas under conditions where the polymer/porphyrin interactions were weakened, the complex assembled at the borders between the polymer and fullerene phases. This concept could potentially be applied to various combinations of porphyrin/fullerene systems in semiconducting polymer thin films to develop polymer solar cells with excellent performance. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41629.     

The nature of polymer grafts and substrate shape on the surface degradation of poly(l‐lactide)

Surface grafting of functional polymers is an effective method to alter material properties and degradation behavior. Two different substrate shapes of poly(l ‐lactide) (PLLA), i.e., films and microparticles, were surface‐grafted with hydrophilic monomers, and their surface degradation was monitored. Surface grafting with a hydrophilic and acidic polymer graft [acrylic acid (AA)] induced large alterations in the surface morphology and topography of the films. In contrast, hydrophilic and neutral polymer grafts [acrylamide (AAm)] had no significant effect on the surface degradation behavior, while the PLLA reference and co‐monomeric (AA/AAm) polymer‐grafted samples exhibited intermediate surface degradation rates. The grafted PAA chains induced a local acidic environment on the surface of the substrates, which in turn catalyzed the surface degradation process. This effect was more pronounced in the films than in the microparticles. Thus, the nature of the grafted chains and substrate geometry were shown to affect the surface degradation behavior of PLLA substrates. © 2015 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42736.