Fabrication and drug release properties of poly(5‐benzyloxy‐trimethylene‐co‐glycolide) microspheres

Poly(5‐benzyloxy‐trimethylene carbonate‐co‐glycolide) random copolymers were synthesized through the ring‐opening polymerization of 5‐benzyloxy‐trimethylene carbonate and glycolide (GA). The copolymers with different compositions, PBG‐1 with 17% GA units and PBG‐2 with 45% GA units, were obtained. Using these copolymers, microsphere drug delivery systems with submicron sizes were fabricated using an “ultrasonic assisted precipitation method.” The in‐vitro drug release from these microspheres was investigated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and properties of random copolymers of 2,2‐dimethyltrimethylene carbonate and ethylene carbonate catalyzed by lanthanide tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)

Random copolymers of 2,2‐dimethyltrimethylene carbonate and ethylene carbonate (EC) were synthesized with lanthanide tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)s [Ln(DBMP)₃; Ln = La, Nd, Sm, or Dy] as catalysts, among which La(DBMP)₃ showed the highest activity. Poly(2,2‐dimethyltrimethylene carbonate‐co‐ethylene carbonate)s [poly(DTC‐co‐EC)]s with high molecular weights were prepared at room temperature and characterized with ¹H‐NMR and size exclusion chromatography. The thermal behavior and crystalline properties of the poly(DTC‐co‐EC)s were analyzed with differential scanning calorimetry, thermogravimetric analysis, and X‐ray diffraction. The crystallinity and melting temperatures of the poly(DTC‐co‐EC)s both decreased with increasing EC content in the copolymers. The mechanical properties of these copolymers were also investigated with dynamic mechanical analysis and tensile strength measurements, which revealed that a reduction of the glass‐transition temperature and great enhancement of the tensile properties could be achieved with higher EC contents. These improvements in the thermal and mechanical properties indicate potential applications in biomedical research for novel polycarbonates. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A biodegradable diblcok copolymer poly(ethylene glycol)‐block‐poly(L‐lactide‐co‐2‐methyl‐2‐carboxyl‐propylene carbonate): Docetaxel and RGD conjugation

A diblcok copolymer monomethoxy poly (ethyleneglycol)‐block‐poly(L ‐lactide‐co‐2‐methyl‐2‐carboxyl‐propylene carbonate) (MPEG‐b‐P(LA‐co‐MCC)) was obtained by copolymerization of L ‐lactide (LA) and 2‐methyl‐2‐benzoxycarbonyl‐propylene carbonate (MBC) and subsequent catalytic hydrogenation. The pendant carboxyl groups of the copolymer MPEG‐b‐P(LA‐co‐MCC) were conjugated with antitumor drug docetaxel and tripeptide arginine‐glycine‐aspartic acid (RGD), respectively. ¹H‐NMR spectra confirmed the structure of the copolymer MPEG‐b‐P(LA‐co‐MCC/docetaxel) and MPEG‐b‐P(LA‐co‐MCC/RGD). In vitro antitumor assay indicates that the MPEG‐b‐P(LA‐co‐MCC/docetaxel) conjugate shows high cytotoxic activity against HeLa cancer cells. Cell adhesion and spreading experiment shows that copolymer MPEG‐b‐P(LA‐co‐MCC/RGD) is of benefit to cell adherence and is a promising biodegradable material for cell and tissue engineering. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Liver‐targeting doxorubicin‐conjugated polymeric prodrug with pH‐triggered drug release profile

The aim of the research presented was to develop a potential liver‐targeting prolonged‐circulation polymeric prodrug of doxorubicin (Dox) with a pH‐triggered drug release profile. In particular, linear dendritic block copolymers composed of polyamidoamine dendrimer (PAMAM) and poly(ethylene glycol) (PEG; number‐average molecular weight of 2000 g mol^?1) with or without galactose (Gal) were synthesized. Dox was coupled to the copolymers via an acid‐labile hydrazone linker. These prodrugs, designated Gal‐PEG‐b‐PAMAM‐Dox_n and mPEG‐b‐PAMAM‐Dox_m, showed accelerated Dox release as the pH decreased from 8.0 to 5.6. Cytotoxicity of the prodrugs was lower than that of free Dox due to the gradual drug release nature. Compared to mPEG‐b‐PAMAM‐Dox_m, Gal‐PEG‐b‐PAMAM‐Dox_n showed rather high cytotoxicity against Bel‐7402, suggestive of its galactose receptor‐mediated enhanced tumor uptake. This galactose receptor‐mediated liver‐targeted profile was further confirmed by the prolonged retention time in hepatoma tissue monitored using magnetic resonance imaging. Gal‐PEG‐b‐PAMAM‐Dox_n showed better in vivo antitumor efficacy than free Dox, suggesting its great potential as a polymeric antitumor prodrug. Copyright © 2010 Society of Chemical Industry     

Preparation of acrylamide‐based poly‐HIPEs with enhanced mechanical strength using PVDBM‐b‐PEG‐emulsified CO2‐in‐water emulsions

Poly(vinyl acetate‐alt‐dibutyl maleate)‐block‐poly(ethylene glycol) (PVDBM‐b‐PEG) copolymers were synthesized via reversible addition–fragmentation chain transfer radical polymerization and used as emulsifiers to form stable CO₂‐in‐water high internal phase emulsions (C/W HIPEs). Then, highly interconnected cellular polyacrylamide (PAM) and poly(acrylamide‐co‐N‐hydroxymethyl acrylamide) [P(AM‐co‐HMAM)] poly‐HIPEs with enhanced mechanical strength were prepared based on the stable C/W HIPEs. The porous structures of the PAM poly‐HIPEs, as well as morphology and compressive modulus, could be influenced by the surfactant concentration and the length of the CO₂‐philic tails of the surfactants. PAM poly‐HIPEs with the smallest average pore diameter (11.12 ± 0.62 μm) and the highest compressive modulus (22.65 ± 0.10 MPa) could be obtained by using the short CO₂‐philic chains of the PVDBM‐b‐PEG surfactant at a high concentration (1.0 wt %). Moreover, with the copolymerization of N‐hydroxymethyl acrylamide (HMAM) comonomers with acrylamide, the compressive modulus of the obtained P(AM‐co‐HMAM) poly‐HIPEs was three times higher than that of PAM poly‐HIPEs. Both PAM and P(AM‐co‐HMAM) poly‐HIPEs were employed as scaffolds to guide H9c2 cardiac muscle cellular growth. Fluorescence images showed that a smaller average pore size and a narrower pore‐size distribution were helpful for cell growth and proliferation on these materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46346.     

Ultrasonochemical‐assisted fabrication and evaporation‐ induced self‐assembly (EISA) of POSS‐SiO2@Ag core/ABA triblock copolymer nanocomposite film

Poly(ethylene glycol)‐octafunctionalized polyhedral oligomeric silsesquioxane (POSS) (M_n = 5576.6 g/mol) alloying agent stabilized amphiphilic silica@silver metalloid nanocomposite blended with a triblock copolymer poly(p‐dioxanone‐co‐caprolactone)‐block‐poly(ethylene oxide)‐block‐poly(p‐dioxanone‐co‐caprolactone) (POSS‐SiO₂@Ag/PPDO‐co‐PCL‐b‐PEG‐b‐PPDO‐co‐PCL) has been synthesized in both water and in organic medium utilizing ultrasonochemical reaction. The POSS stabilized pre‐made metalloid was successfully dispersed in amphiphilic PPDO‐co‐PCL‐b‐PEG‐b‐PPDO‐co‐PCL (ABA) triblock copolymer matrix of molecular weight 45.9 × 10⁴ g/mol. The mechanism of synthesis of high concentration of SiO₂@Ag nanocomposite from TEOS/AgNO₃ (in the presence of NH₄OH as catalyst/NaBH₄ as reductant) nonmetal/metal precursors and the successful EISA of POSS‐SiO₂@Ag/ABA nanocomposite into films has been discussed. The successful synthesis of metalloid nanocomposite was morphologically accessed by field emission‐scanning electron microscopy, transmission electron microscopy and atomic force microscopy. Surface plasmon resonance was ensured from UV–visible spectral analysis. Identity and the crystallinity of as prepared nanocomposite were studied by X‐ray diffractometer. Structural and luminescence properties of the nanocomposite were examined by Fourier transform infrared spectroscopy and photoluminescence. Thermogravimetric analysis was carried out to study the thermal stability of the resulting hybrid nanocomposite. The resultant inorganic–organic nanocomposite can be easily suspended in water and would be useful in variety of applications. POLYM. COMPOS., 31:1620–1627, 2010. © 2009 Society of Plastics Engineers     

Ring opening polymerization of aliphatic cyclic carbonates in the presence of natural amino acids

Poly(dimethyl trimethylene carbonate) (PDTC) and poly(trimethylene carbonate) (PTMC) were synthesized by ring‐opening polymerization (ROP) of dimethly trimethylene carbonate (DTC) and trimethylene carbonate (TMC) in the presence of five kinds of natural amino acids (L ‐alanine, L ‐valine, L ‐leucine, L ‐proline, and L ‐phenylalanine). PDTCs with number‐average molecular weight (M_n) from 6700 to 18,900 g/mol and PTMCs with M_n from 7200 to 17,800 g/mol were obtained at a feed ratio of [monomer]/[L ‐phenylalanine] ranging from 50 to 200. The results of ¹H nuclear magnetic resonance and titration proved amino acid connecting onto the polymer backbone. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of composition on morphology structure and cell affinity of poly(caprolactone‐co‐glycolide)‐co‐poly(ethylene glycol) microspheres

Poly(caprolactone‐co‐glycolide)‐co‐poly(ethylene gylcol) copolymers (PCEG) with various composition were synthesized by copolymerization of GA, CL, and PEG. PCEG microspheres were fabricated by oil‐in‐water (o/w) emulsion and solvent‐evaporation technique. Effect of chemical composition on hydrophilicity, crystallinity, and degradation of the PCEG was investigated. It was demonstrated that morphology structure of the microspheres was greatly influenced by chemical composition and hydrophilicity of the PCEG polymer. PCEG microspheres could change from a smooth structure to a regular porous structure and an irregular structure. Moreover, the pore size of them increased with increment of PEG content and length. Cell attachment and growth on the PCEG microspheres were evaluated by using mouse NIH 3T3 fibroblasts as model cells in vitro. The result showed that the PCEG microspheres with large porous structure were more favorable for cell attachment and growth. Thus the PCEG microspheres with rapid degradation rate and large porous structure possess potential use as injectable scaffolds in tissue engineering. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42861.     

Synthesis and characterization of biodegradable block copolymers of poly(propylene fumarate‐co‐sebacate)‐co‐poly(ethylene glycol) and poly(ethylene fumarate‐co‐sebacate)‐co‐poly(ethylene glycol)

The synthesis of two low molecular weight linear unsaturated oligoester precursors, poly(propylene fumarate‐co‐sebacate) (PPFS) and poly(ethylene fumarate‐co‐sebacate) (PEFS), are described. PPFS, PEFS, and poly(ethylene glycol) are then used to prepare poly(propylene fumarate‐co‐sebacate)‐co‐poly(ethylene glycol) (PPFS‐co‐PEG) and poly(ethylene fumarate‐co‐sebacate)‐co‐poly(ethylene glycol) (PEFS‐co‐PEG) block copolymers. The products thus obtained are investigated in terms of the molecular weight, composition, structure, thermal properties, and solubility behavior. A number of design parameters including the molecular weights of PPFS, PEFS, and PEG, the reaction time in the polymer synthesis, and the weight ratio of PEG to PPFS or to PEFS are varied to assess their effects on the product yield and properties. The hydrolytic degradation of PPFS‐co‐PEG and PEFS‐co‐PEG in an isotonic buffer (pH 7.4, 37°C) is investigated, and it is found that the fumarate ester bond cleaves faster than does the sebacate ester bond. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 295–300, 2004     

Synthesis and characterization of a novel stimuli‐responsive magnetite nanohydrogel based on poly(ethylene glycol) and poly(N‐isopropylacrylamide) as drug carrier

A novel stimuli‐responsive magnetite nanohydrogel (MNHG), namely [poly(ethylene glycol)‐block‐poly(N‐isopropylacrylamide‐co‐maleic anhydride)₂]‐graft‐poly(ethylene glycol)/Fe₃O₄ [PEG‐b‐(PNIPAAm‐co‐PMA)₂]‐g‐PEG/Fe₃O₄, was successfully developed. For this purpose, NIPAAm and MA monomers were block copolymerized onto PEG‐based macroinitiator through atom transfer radical polymerization technique to produce PEG‐b‐(PNIPAAm‐co‐PMA)₂. The synthesized Y‐shaped terpolymer was crosslinked through the esterification of maleic anhydride units using PEG chains to afford a hydrogel. Afterward, magnetite nanoparticles were incorporated into the synthesized hydrogel through the physical interactions. The chemical structures of all synthesized samples were characterized using Fourier transform infrared and proton nuclear magnetic resonance spectroscopies. Morphology, thermal stability, size, and magnetic properties of the synthesized MNHG were investigated. In addition, the doxorubicin hydrochloride loading and encapsulation efficiencies as well as stimuli‐responsive drug release ability of the synthesized MNHG were also evaluated. The drug‐loaded MNHG at physiological condition exhibited negligible drug release values. In contrast, at acidic (pH 5.3) condition and a little bit higher temperature (41 °C) the developed MNHG showed higher drug release values, which qualified it for cancer chemotherapy due to especial physiology of cancerous tissue in comparison with the surrounding normal tissue. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46657.     

Non‐catalyst synthesis and in vitro drug release property of poly(5,5‐dimethyl‐1,3‐dioxan‐2‐one)‐block‐methoxy poly(ethylene glycol) copolymers

A series of poly(5,5‐dimethyl‐1,3‐dioxan‐2‐one)‐block‐methoxy poly(ethylene glycol) (PDTC‐b‐mPEG) copolymers were synthesized by the ring‐opening polymerization of 5,5‐dimethyl‐1,3‐dioxan‐2‐one (DTC) in bulk, using methoxy poly(ethylene glycol) (mPEG) as initiator without adding any catalysts. The resulting copolymers were characterized by Fourier transform infrared spectra, ¹H NMR and gel permeation chromatography. The influences of some factors such as the DTC/mPEG molar feed ratio, reaction time and reaction temperature on the copolymerization were investigated. The experimental results showed that mPEG could effectively initiate the ring‐opening polymerization of DTC in the absence of catalyst, and that the copolymerization conditions had a significant effect on the molecular weight of PDTC‐b‐mPEG copolymer. In vitro drug release study demonstrated that the amount of indomethacin released from PDTC‐b‐mPEG copolymer decreased with increase in the DTC content in the copolymer. © 2013 Society of Chemical Industry     

Application of microwave‐assisted click chemistry in the preparation of functionalized copolymers for drug conjugation

The aim of this study is to develop azido‐carrying biodegradable polymers and their postfunctionalization with alkynyl compounds via click chemistry and to investigate their potential use in drug delivery. Azido polymers were prepared by ring‐opening polymerization of cyclic carbonate monomer, 2,2‐bis(azidomethyl)trimethylene carbonate (ATC) with lactide using stannous octoate as catalyst. Several alkynyl compounds were selected to investigate the feasibility and reaction condition of click chemistry. With microwave‐assisting, the reaction time of click chemistry was shortened to 5 min. By using poly(ethylene glycol) (PEG) as macroinitiator, amphiphilic block copolymer mPEG‐b‐P(LA‐co‐ATC) was obtained and it could self‐assemble into micelles by solvent replacement method. The pendant groups were used for conjugating anticancer drugs gemcitabine and paclitaxel and fluorescent dye Rhodamine B. 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide was used to assay the cytotoxicity of the conjugate micelles against SKOV‐3 and HeLa cell lines. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

TAT‐modified mixed micelles as biodegradable targeting and delivering system for cancer therapeutics

A mixed micellar system of novel function was designed and synthesized by co‐assembling TAT (cell penetrating peptide)‐modified poly (ethylene glycol)‐poly(l ‐lactide) (PEG‐PLA) copolymer with the drug‐conjugated poly(ethylene glycol)‐b‐poly(l‐ lactide‐co‐2‐methyl‐2‐carboxyl‐propylene carbonate) (mPEG‐b‐P(LA‐co‐MCC)) copolymer. UV‐Vis, Matrix‐assisted laser desorption/ionization time‐of‐flight, and XPS were used to ensure the successful modification of the copolymers with TAT and anti‐tumor drugs. The size of spherical nanomicelles increased from 50 to 60 nm as of empty polymeric micelles to 100–150 nm as of drug‐loaded ones, determined by dynamic light scattering and TEM. Daunorubicin was selected as model drug for in vitro evaluations on different cell lines. 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay clearly indicated an improved cell growth inhibition of the TAT‐modified mixed micelles. While green fluorescent protein was used as a marker for the mixed micelle, small amount of DMSO was necessary to enhance the accumulation of the mixed micelles in cell lines Caski. Mediated by TAT, mixed micelles containing Apoptin (a tumor‐specific apoptosis drug) showed higher level of tumor cell internalization and growth inhibition than that of mixed micelles without TAT modification. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4598–4607, 2013     

Synthesis and properties of polycarbonate copolymers of trimethylene carbonate and 2‐phenyl‐5,5‐bis(hydroxymethyl) trimethylene carbonate

The polycarbonate copolymers poly[trimethylene carbonate‐co‐2‐phenyl‐5,5‐bis(hydroxymethyl) trimethylene carbonate] [P(TMC‐co‐PTC)] were synthesized by the ring‐opening polymerization of trimethylene carbonate (TMC) and 2‐phenyl‐5,5‐bis(hydroxymethyl) trimethylene carbonate (PTC) with tin(II) 2‐ethylhexanoate and aluminum isopropoxide as the catalysts. These copolymers were further reduced by a palladium/carbonate (Pd/C; 10%) catalyst to produce partly deprotected copolymers. These two types of copolymers were characterized by ¹H‐NMR, Fourier transform infrared spectroscopy, UV spectroscopy, gel permeation chromatography, differential scanning calorimetry, and an automatic contact angle meter. The influences of the feed molar ratio of the monomers, the catalyst concentration, the reaction time, and the reaction temperature on the copolymerization process were also studied. The copolymerization of the TMC and PTC monomers was a nonideal copolymerization, and the copolymerization reactivity ratio of TMC was higher than that of PTC. In vitro degradation tests indicated that the partly deprotected copolymers possessed faster degradation rates and more hydrophilicity than the corresponding unreduced copolymers. Moreover, the degradation of these two type copolymers increased when the pH value of the buffer solutions decreased. In vitro drug‐release experiments showed that these two types of copolymers had steady drug‐release rates and good controlled release properties. Moreover, the partly deprotected copolymers had faster drug‐release rates than the corresponding unreduced copolymers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and characterization of cholic acid‐containing biodegradable hydrogels by photoinduced copolymerization

A cholic acid (CA)‐containing biodegradable hydrogel (PLA‐PEG‐PLA‐co‐MACAH) was synthesized from the photoinduced copolymerization of a CA‐modified methacrylate monomer (MACAH), bearing a spacer of hexane‐1,6‐diol spacer between the methacryloyl and the cholanoate moieties, and a macromonomer (PLA‐PEG‐PLA‐DA), bearing two acryloyl end groups derived from a poly(lactic acid)‐b‐poly(ethylene glycol)‐b‐poly(lactic acid) triblock copolymer. The structure of MACAH was confirmed by FTIR, ¹H‐NMR, and MS. The hydrogel PLA‐PEG‐PLA‐co‐MACAH was characterized by scanning electron microscopy and X‐ray diffraction. The experiment results showed that the swelling ratios of the hydrogels decreased with the increase of the CA fraction. The investigation on the in vitro degradation of the hydrogel showed that the CA‐containing hydrogels degraded much slower than the hydrogels without CA component. The bioactivity of the synthesized hydrogels was assessed by the simulated body fluid method. The observed formation of hydroxyapatite on the scaffold of the hydrogels indicated that the hydrogels possess good bioactivity. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and properties of a biodegradable polymer as a novel drug delivery system

Poly (DL ‐lactic acid‐co‐glycolic acid)‐co‐poly(ethylene glycol) was synthesized by bulk ring‐opening polymerization of DL ‐lactide/glycolide/poly(ethylene glycol) using stannous chloride as an initiator. The molecular structure of the copolymer was analyzed by IR, ¹H NMR, and DSC. The degradation behavior of copolymer was assayed by the reduction of molecular weight, the loss‐in‐mass, and the changes of pH value for degradation medium. The different contents of PGA and PEG in the molecules of the copolymer could control the degradation rate of polymer. Human Serum Albumin (HSA) was chosen as the model hydrophilic drug and encapsulated in the copolymer. The HA‐loaded copolymer microspheres were characterized by the diameter, diameter distribution of the microspheres, and the loading efficiency. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3150–3156, 2003     

Temperature‐responsiveness and sustained delivery properties of macroporous PEG‐co‐PNIPAAm‐co‐PCL hydrogels

A series of novel thermosensitive macroporous poly (ethylene glycol) (PEG)‐co‐poly(N‐isopropylacrylamide) (PNIPAAm)‐co‐poly (ε‐caprolactone) (PCL) hydrogels were synthesized via in situ free radical polymerization. Poly(ethylene glycol diacrylate) (PEGDAc) and poly(ε‐caprolactone diacrylate) (PCLDAc) were prepared as macrocrosslinkers. All compounds were investigated by Nuclear Magnetic Resonance (NMR) and Fourier transform‐infrared spectroscopy (FT‐IR). Differential Scanning Calorimetry (DSC) results showed the lower critical solution temperatures (LCSTs) of the gels were at around 31°C. The macroporous gels not only had considerable swelling ratios, but also exhibited rapid swelling kinetics and response sensitivity. Above mentioned hydrogels showed a remarkable oscillatory swelling–deswelling transition, making them have potential application in long‐term drug delivery. POLYM. ENG. SCI., 55:223–230, 2015. © 2014 Society of Plastics Engineers     

Biodegradations of statistical copolymers composed of D,L‐lactide and cyclic carbonates

Syntheses and biodegradation of statistical copolymers of D ,L ‐lactide (D ,L ‐LA) with trimethylene carbonate (TMC), rac‐1‐methyltrimethylene carbonate (1‐MTMC) and 2,2‐dimethyltrimethylene carbonate (2,2‐DTMC) were investigated at various monomer ratios using SmMe(C₅Me₅)₂THF as an initiator at 80 °C for 24 h in toluene. Biodegradations of poly(D ,L ‐LA‐co‐racemo‐1‐MTMC) (95/5) and poly(D ,L ‐LA‐co‐2,2‐DTMC) (98/2) with a compost at 60 °C proceed rapidly. Enzymatic degradations of these polymers were also performed using cholesterol esterase, lipoprotein lipase and proteinase K. Only poly(D ,L ‐LA‐co‐TMC) was biodegraded with cholesterol esterase, while poly(TMC), poly(1‐MTMC), poly(2,2‐DTMC) and poly(D ,L ‐LA) were barely degraded with these enzymes. Biodegradations of poly(D ,L ‐LA‐co‐TMC) (87/13) and poly(D ,L ‐LA‐co‐racemo‐1‐MTMC) (95/5) are rapid using proteinase K. Physical properties of these copolymers were also described. © 2003 Society of Chemical Industry     

Competitive hydrogen bonding mechanisms underlying phase behavior of triple poly(N‐vinyl pyrrolidone)–poly(ethylene glycol)–poly(methacrylic acid‐co‐ethylacrylate) blends

Differential scanning calorimetry (DSC) of triple blends of high molecular weight poly(N‐vinyl pyrrolidone) (PVP) with oligomeric poly(ethylene glycol) (PEG) of molecular weight 400 g/mol and copolymer of methacrylic acid with ethylacrylate (PMAA‐co‐EA) demonstrates partial miscibility of polymer components, which is due to formation of interpolymer hydrogen bonds (reversible crosslinking). Because both PVP and PMAA‐co‐EA are amorphous polymers and PEG exhibits crystalline phase, the DSC examination is informative on the phase state of PEG in the triple blends and reveals a strong competition between PEG and PMAA‐co‐EA for interaction with PVP. The hydrogen bonding in the triple PVP–PEG–PMAA‐co‐EA blends has been established with FTIR Spectroscopy. To evaluate the relative strengths of hydrogen bonded complexes in PVP–PEG–PMAA‐co‐EA blends, quantum‐chemical calculations were performed. According to this analysis, the energy of H‐bonding has been found to diminish in the order: PVP–PMAA‐co‐EA–PEG(OH) > PVP–(OH)PEG(OH)–PVP > PVP–H₂O > PVP–PEG(OH) > PMAA‐co‐EA–PEG(? O? ) > PVP–PMAA‐co‐EA > PMAA‐co‐EA–PEG(OH). Thus, most stable complexes are the triple PVP–PMAA‐co‐EA–PEG(OH) complex and the complex wherein comparatively short PEG chains form simultaneously two hydrogen bonds to PVP carbonyl groups through both terminal OH‐groups, acting as H‐bonding crosslinks between longer PVP backbones. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

The role of the ratio (PEG:PPG) of a triblock copolymer (PPG‐b‐PEG‐b‐PPG) in the cure kinetics,miscibility and thermal and mechanical properties in an epoxy matrix

The aim of this study was to evaluate the role of different poly(ethylene glycol):poly(propylene glycol) (PEG:PPG) molar ratios in a triblock copolymer in the cure kinetics, miscibility and thermal and mechanical properties in an epoxy matrix. The poly(propylene glycol)‐block‐poly(ethylene glycol)‐block‐poly(propylene glycol) (PPG‐b‐PEG‐b‐PPG) triblock copolymers used had two different molecular masses: 3300 and 2000 g mol^?1. The mass concentration of PEG in the copolymer structure played a key role in the miscibility and cure kinetics of the blend as well as in the thermal–mechanical properties. Phase separation was observed only for blends formed with the 3300 g mol^?1 triblock copolymer at 20 wt%. Concerning thermal properties, the miscibility of the copolymer in the epoxy matrix reduced the T_g value by 13 °C, although a 62% increase in fracture toughness (K_IC) was observed. After the addition of PPG‐b‐PEG‐b‐PPG with 3300 g mol^?1 there was a reduction in the modulus of elasticity by 8% compared to the neat matrix; no significant changes were observed in T_g values for the immiscible system. The use of PPG‐b‐PEG‐b‐PPG with 2000 g mol^?1 reduced the modulus of elasticity by approximately 47% and increased toughness (K_IC) up to 43%. Finally, for the curing kinetics of all materials, the incorporation of the triblock copolymer PPG‐b‐PEG‐b‐PPG delayed the cure reaction of the DGEBA/DDM (DGEBA, diglycidyl ether of bisphenol A; DDM, Q3‐4,4′‐Diaminodiphenylmethane) system when there is miscibility and accelerated the cure reaction when it is immiscible. All experimental curing reactions could be fitted to the Kamal autocatalytic model presenting an excellent agreement with experimental data. This model was able to capture some interesting features of the addition of triblock copolymers in an epoxy resin. © 2018 Society of Chemical Industry