Chemosynthesis and characterization of fully biomass‐based copolymers of ethylene glycol, 2,5‐furandicarboxylic acid,and succinic acid

Poly(ethylene 2,5‐furandicarboxylate‐co‐ethylene succinate) (PEFS) copolymers of 2,5‐furandicarboxylic acid (FDCA) and succinic acid with 11.98–91.32 mol % FDCA composition were synthesized via melt polycondensation in the presence of ethylene glycol using tetrabutyl titanate as a catalyst. PEFSs' molecular weight, thermal properties, and molar composition were determined by Fourier transform infrared spectroscopy, gel permeation chromatography, intrinsic viscosity, ¹H NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and wide‐angle X‐ray diffraction (WAXD) measurements. From experimental conditions, we obtained random copolymers with number‐average molecular weights exceeding 25,600, determined by GPC and ¹H NMR analyses. DSC analysis revealed that PEFS copolymers' melting temperatures differed depending on EF units' percentage. TGA studies confirmed that all PEFS copolymers' thermal stability exceeded 300°C. From WAXD analysis, it is observed that the PEFS copolymer crystal structure was similar to that of PES when EF unit was 11.98 mol % and to that of PEF when EF units were 74.35 and 91.32 mol %. These results benefit this novel biodegradable copolymer to be used as a potential biomaterial. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1415‐1420, 2013     

Polymer blends of poly(ethylene‐2,6‐naphthalate) with polystyrene compatibilized by styrene‐glycidyl methacrylate copolymers. I. Rheology,morphology, and mechanical properties

The compatibilization of blends of poly(ethylene‐2,6‐naphthalate) (PEN) with polystyrene (PS), through the styrene‐glycidyl methacrylate copolymers (SG) containing various glycidyl methacrylate (GMA) contents, was investigated in this study. SG copolymers are able to react with PEN terminal groups during melt blending, resulting in the formation of desirable SG‐g‐PEN copolymers in the blend. These in situ formed copolymers tend to reside along the interface preferentially as the result of interfacial reaction and thus function as effective compatibilizers in PEN/PS blends. The compatibilized blends exhibit higher viscosity, finer phase domain, and improved mechanical properties. It is found that the degree of grafting of the in situ formed SG‐g‐PEN copolymer has to be considered as well. In blends compatibilized with the SG copolymer containing higher GMA content, heavily grafted copolymers would be produced. The length of the styrene segment in these heavily grafted copolymers would be too short to penetrate deep enough into the PS phase to form effective entanglements, resulting in the lower compatibilization efficiency in PEN/PS blends. Consequently, the in situ formation of SG‐g‐PEN copolymers with an optimal degree of grafting is the key to achieving the best performance for the eventually produced PEN/PS blends through SG copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 967–975, 2003     

Effect of glycols on the properties of polyester polyols and of room‐temperature‐curable casting polyurethanes

A series of liquid polyester polyols (PEs) from adipic acid (AA), phthalic anhydride (PA) and trihydroxymethylpropane (TMP), and such glycols as ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG), butanediol (BD) and hexanediol (HD), were prepared. Polyurethanes (PUs) were obtained from the PEs and polyaryl polymethylene isocyanate (PAPI) at room temperature. The effects of the structures of the glycols on viscosity, glass transition temperature and crystallinity of the PEs, and the mechanical, thermal and boiling‐water‐resistant properties of PUs were studied. The experiments showed that the viscosities and glass transition temperatures of the PEs decreased as the length of the glycol chains increased. The polyester based on HD lost flowability because of crystallization. The tensile strength and hardness of the PUs obtained decreased with increasing the length of the glycol chains, while the resistance to thermal deformation and boiling water increased. Thermogravimetric analysis demonstrated that thermal degradation of the polyurethane based on DEG proceeded in one step and for the others in two steps. The initial degradation temperature of the polyurethane based on EG was the lowest and that of the polyurethane based on BD was the highest. The residue of the former at 450 °C was the greatest, while that of the latter was the lowest. Copyright © 2004 Society of Chemical Industry     

Synthesis,characterization, and hydrolytic degradation of biodegradable poly(ether ester)‐urethane copolymers based on ε‐caprolactone and poly(ethylene glycol)

In this article, a new kind of biodegradable poly(ε‐caprolactone)‐poly(ethylene glycol)‐poly(ε‐caprolactone)‐based polyurethane (PCEC‐U) copolymers were successfully synthesized by melt‐polycondensation method from ε‐caprolactone (ε‐CL), poly(ethylene glycol) (PEG), 1,4‐butanediol (BD), and isophorone diisocyanate (IPDI). The obtained copolymers were characterized by ¹H‐nuclear magnetic resonance (¹H‐NMR), FTIR, and gel permeation chromatography (GPC). Thermal properties of PCEC‐U copolymers were studied by DSC and TGA/DTG under nitrogen atmosphere. Water absorption and hydrolytic degradation behavior of these copolymers were also investigated. Hydrolytic degradation behavior was studied by weight loss method. ¹H‐NMR and GPC were also used to characterize the hydrolytic degradation behavior of PCEC‐U copolymers. The molecular weight of PCL block and PEG block in soft segment and the content of hard segment strongly affected the water absorption and hydrolytic degradation behavior of PCEC‐U copolymers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Crystallization behavior of biodegradable amphiphilic poly(ethylene glycol)‐poly(L‐lactide) block copolymers

Poly(ethylene glycol)‐poly(L ‐lactide) diblock and triblock copolymers were prepared by ring‐opening polymerization of L ‐lactide with poly(ethylene glycol) methyl ether or with poly(ethylene glycol) in the presence of stannous octoate. Molecular weight, thermal properties, and crystalline structure of block copolymers were analyzed by ¹H‐NMR, FTIR, GPC, DSC, and wide‐angle X‐ray diffraction (WAXD). The composition of the block copolymer was found to be comparable to those of the reactants. Each block of the PEG–PLLA copolymer was phase separated at room temperature, as determined by DSC and WAXD. For the asymmetric block copolymers, the crystallization of one block influenced much the crystalline structure of the other block that was chemically connected to it. Time‐resolved WAXD analyses also showed the crystallization of the PLLA block became retarded due to the presence of the PEG block. According to the biodegradability test using the activated sludge, PEG–PLLA block copolymer degraded much faster than PLLA homopolymers of the same molecular weight. © 1999 John Wiley amp; Sons, Inc. J Appl Polym Sci 72: 341–348, 1999     

Novel copolyesters containing naphthalene structure III. Copolyesters prepared from 2,6‐dimethyl naphthalate,ethylene glycol,and 2,2‐dialkyl‐1,3‐propanediols

Poly(ethylene naphthalate) (PEN) copolymers were prepared by melt polycondensation of dimethyl naphthalate and excess ethylene glycol with 5–40 mol % (in feed) of 1,3‐propanediol or 2,2‐dialkyl‐1,3‐propanediols, where the dialkyl groups are dimethyl, diethyl, and butyl‐ethyl. No significant depression of reduced specific viscosity was observed. The comonomer contents in the copolymers are considerably higher than those in the feed. The effects of the copolymer composition on the structures of the films were investigated using thermal analyses, density measurements, X‐ray diffraction methods, and other physical tests. The crystallinities and densities of heat‐treated films decreased with increasing content of comonomer and length of alkyl side chain in the comonomer. The glass transition temperature (T_g) and melting temperature (T_m) were decreased by the copolymerization, while an increase in the length of the alkyl side chain hardly affected T_ms of the heat‐treated films. Alkali resistance, moisture resistance, dye ability, and thermal shrinkage were increased by the incorporation of comonomer having an alkyl side chain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2754–2763, 2001     

Preparation and biodegradation of hydroxyl terminated poly(fumaric acid‐co‐diethylene glycol) and its segmented polyurethane

Hydroxyl terminated poly(fumaric acid‐co‐diethylene glycol), poly(FA‐co‐DEG) was prepared by melt polycondensation. The resultant unsaturated aliphatic polyester was characterized by Fourier transform infrared (FTIR) spectroscopy, hydroxyl value, acid value, and intrinsic viscosity. Its enzymatic degradation and crosslinking behavior as well as the effect of crosslinking degree on enzymatic degradation were also investigated. The crosslinking degree and reduction of carbon–carbon double bonds revealed excellent self‐crosslinking nature of poly(FA‐co‐DEG) at high temperature. The results of enzymatic degradation showed that poly(FA‐co‐DEG) has excellent biodegradability and that the biodegradation can be controlled by the crosslinking degree. Polyurethane was prepared by the reaction of poly(FA‐co‐DEG), 2,4‐toluene diisocyanate (TDI), and 1,4‐butanediol (BD). It was found that the biodegradation of the obtained polyurethane was slower than that of the original unsaturated aliphatic polyester poly(FA‐co‐DEG). The peeling strength of the polyurethane was very high, supporting better adhesion property with enhanced crosslinking. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis of block copolymers via redox polymerization

Polymerization and copolymerization of vinyl monomers such as acrylamide, acrylonitrile, vinyl acetate, and acrylic acid with a redox system of Ce(IV) and organic reducing agents containing hydroxy groups were studied. The reducing compounds were poly(ethylene glycol)s, halogen‐containing polyols, and depolymerization products of poly(ethylene terephthalate). Copolymers of poly(ethylene glycol)s‐b‐polyacrylonitrile, poly(ethylene glycol)s‐b‐poly(acrylonitrile‐co‐vinyl acetate), poly(ethylene glycol)s‐b‐polyacrylamide, poly(ethylene glycol)s‐b‐poly(acrylamide‐co‐vinyl acetate), poly(1‐chloromethyl ethylene glycol)‐bpoly(acrylonitrile‐co‐vinyl acetate), and bis[poly(ethylene glycol terephthalate)]‐b‐poly(acrylonitrile‐co‐vinyl acetate) were produced. The yield of acrylamide polymerization and the molecular weight of the copolymer increased considerably if about 4% vinyl acetate was added into the acrylamide monomer. However, the molecular weight of the copolymer was decreased when 4% vinyl acetate was added into the acrylonitrile monomer. Physical properties such as solubility, water absorption, resistance to UV light, and viscosities of the copolymers were studied and their possible uses are discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1385–1395, 1999     

Surface modification of contact lenses using adsorption of ethylene oxide branched copolymers

To examine methods for reducing the amount of adsorbed protein on the surface of contact lenses during use, cationic copolymers containing poly(ethylene oxide) units were synthesized and evaluated as surface modifiers. Poly(ethylene oxide) graft‐branched copolymers of composition 70 mol % dimethylaminoethyl methacrylate (DM) and 30 mol % methoxy polyethylene glycol methacrylate (Mp0G; p = 2, 4, 9; the average number of the ethylene oxide units) were obtained using nonionic monomers containing poly(ethylene oxide) units. The copolymers very efficiently prevented protein adsorption on a contact lens. Contact angle measurements showed that immersion in tear fluid made the lens surface hydrophobic because of adsorption of proteins with hydrophobic residues. The copolymer pretreatment made the lens surface hydrophilic, even after dipping in artificial tear fluid. These results suggest that adsorption of the poly(ethylene oxide) branched copolymer on the contact lens would make the lens surface hydrophilic and prevent protein adsorption. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Crystallization behavior and crystal structure of poly(ethylene‐co‐trimethylene terephthalate)s

A series of random copolymers were synthesized by the bulk polycondensation of dimethyl terephthalate with ethylene glycol (EG) and propane‐1,3‐diol (PDO) in various compositions. Their composition and thermal properties were investigated. The copolymers with 57.7 mol % or more PDO or 14.4 mol % or less PDO were crystallizable, but those with 36–46.2 mol % PDO were amorphous. The nonisothermal crystallization behavior was investigated with varying cooling rates by DSC. Poly(ethylene terephthalate) (PET) and poly(trimethylene terephthalate) (PTT) homopolymers have relatively lower activation energy than their copolymers. PET‐rich copolymers (EG > 85.9%) exhibited PET crystal structure, and exhibited no PTT crystal structure; and PTT‐rich copolymers (PDO > 41.7%) exhibited PTT crystal structure, and exhibited no PET crystal structure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Behavior of poly(ethylene‐co‐olefin) polymers as elastomeric materials

The properties of two new ethylene‐α‐olefin copolymers, namely, ethylene–1‐hexene copolymer (EHC) and ethylene–1‐octadecene copolymers (EOC), synthesized via metallocene catalysts were evaluated. The copolymerization was carried out in an autoclave reactor with Et(Indenyl)₂ZrCl₂/methylaluminoxane as a catalyst system. These single‐site catalysts (metallocene type) allow one to obtain very homogeneous copolymers with excellent control of the molecular weight distribution and proportion of comonomer incorporation. So, copolymers with 18 mol % comonomer in the case of EHC and 12 mol % for EOC were shaped, and activities around 100,000 kg of polymer mol^?1 of Zr bar^?1 h^?1 were reached. The properties of these copolymers were compared with other commercial elastomers, such as ethylene–propylene copolymers synthesized by Ziegler–Natta catalysts and an ethylene–octene copolymer obtained via metallocene catalysts. The results show that these new copolymers, in particular, EOC, had excellent elastomeric properties. Furthermore, they had a relatively low viscosity, which implied a good response during processing. Moreover, the effectiveness of these copolymers as impact modifiers for polyolefins was also studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3008–3015, 2004     

Synthesis and aggregation behavior of four types of different shaped PCL‐PEG block copolymers

Biodegradable, amphiphilic, linear (diblock and triblock) and star‐shaped (three‐armed and four‐armed) poly[(ethylene glycol)‐block‐(ε‐caprolactone)] copolymers (PEG–PCL copolymers) were synthesized by ring‐opening polymerization of ε‐caprolactone (CL) with stannous octoate as a catalyst, in the presence of monomethoxypoly(ethylene glycol) (MPEG), poly(ethylene glycol) (PEG), three‐armed poly(ethylene glycol) (3‐arm PEG) or four‐armed poly(ethylene glycol) (4‐arm PEG) as an initiator, respectively. The monomer‐to‐initiator ratio was varied to obtain copolymers with various PEG weight fractions in a range 66–86%. The molecular structure and crystallinity of the copolymers, and their aggregation behavior in the aqueous phase, were investigated by employing ¹H‐NMR spectroscopy, gel permeation chromatography and differential scanning calorimetry, as well as utilizing the observational data of gel–sol transitions and aggregates in aqueous solutions. The aggregates of the PEG–PCL block copolymers were prepared by directly dissolving them in water or by employing precipitation/solvent evaporation technique. The enthalpy of fusion (ΔH_m), enthalpy of crystallization (ΔH_crys) and degrees of crystallinity (χ_c) of PEG blocks in copolymers and the copolymer aggregates in aqueous solutions were influenced by their PEG weight fractions and molecular architecture. The gel–sol transition properties of the PEG–PCL block copolymers were related to their concentrations, composition and molecular architecture. Copyright © 2006 Society of Chemical Industry     

Studies on the synthesis of block copolymers of acrylonitrile and ethylene oxide

The synthesis of polyacrylonitrile–poly(ethylene oxide) block copolymers was carried out with the use of modified initiator containing azo groups, being a product of reaction between poly(ethylene oxide) (mol wt 6000) with azobisisobutyronitrile. Effects of initiator concentration, temperature, and synthesis time on the yield, composition, and intrinsic viscosity of the copolymers were examined. To confirm the segmental structure of the obtained products, precipitation, fractionation, gel permeation chromatography, infrared, and ¹H nuclear magnetic resonance methods were used. © 1993 John Wiley & Sons, Inc.     

On the interrelationship of transreaction with viscoelastic properties of poly(ethylene terephthalate)/poly(ethylene naphthalate) blends in the presence of nanoclay

An attempt was made to explore the effects of the interchange reactions on the viscoelastic behavior of binary blends based on poly(ethylene terephthalate) (PET)/poly(ethylene naphthalate) (PEN) and their nanocomposites. It was seen that with an increase in the number of extrusion runs and mixing temperature, the extent of reaction (X) and degree of randomness (RD) both increased, whereas the average sequence block lengths values were decreased. On the contrary, the blend composition did not play a significant role on X and RD values. Addition of nanoclay inhibited the transreactions in PET/PEN blends. The absence of crystallization peaks implied that the crystalline structure was destroyed as a result of blending and an amorphous system was created possibly due to the transreactions simultaneously with the formation of random copolymers inhibiting the crystallization process. The rheological investigations showed that the addition of PEN into the PEN/PET blends enhanced the storage modulus, loss modulus, and complex viscosity. The viscosity upswing observed at low‐frequency region in the case of nanocomposite systems evidently confirmed the occurrence of transreactions. Nonetheless, a significant increment in the viscoelastic properties was perceived in the presence of nanoclay corroborating the proper nanoclay distribution throughout the PET/PEN blend system. POLYM. ENG. SCI., 53:2556–2567, 2013. © 2013 Society of Plastics Engineers     

Synthesis and characterization of poly(ϵ‐caprolactone)‐b‐poly(ethylene glycol) block copolymers prepared by a salicylaldimine‐aluminum complex

A series of poly(?‐caprolactone)‐b‐poly(ethylene glycol) (PCL‐b‐PEG) block copolymers with different molecular weights were synthesized with a salicylaldimine‐aluminum complex in the presence of monomethoxy poly(ethylene glycol). The block copolymers were characterized by ¹H NMR, GPC, WAXD, and DSC. The ¹H NMR and GPC results verify the block structure and narrow molecular weight distribution of the block copolymers. WAXD and DSC results show that crystallization behavior of the block copolymers varies with the composition. When the PCL block is extremely short, only the PEG block is crystallizable. With further increase in the length of the PCL block, both blocks can crystallize. The PCL crystallizes prior to the PEG block and has a stronger suppression effect on crystallization of the PEG block, while the PEG block only exerts a relatively weak adverse effect on crystallization of the PCL block. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

The changes of transesterification level in PET/PEN blends with the addition of PET–PEN copolymer

The extent of transesterification in poly(ethylene terephthalate) (PET)/poly(ethylene‐2,6‐naphthalate) (PEN) blends with the addition of PET–PEN copolymers was examined by DSC and ¹H‐NMR measurements to evaluate the factor affecting the reaction level at a given temperature and time. Both block (P(ET‐block‐EN)) and random (P(ET‐ran‐EN)) copolymers were used as the copolymers. At a given treatment temperature and time, the level was increased by the addition of P(ET‐block‐EN) into PET/PEN blends. On the other hand, a reverse change was observed when P(ET‐ran‐EN) was mixed with PET/PEN blends. During the treatment, an inhomogeneous phase of the blends changed into the homogeneous one; however, the change showed little effect on the reaction level. The effects of molecular weight on the reaction level were also examined. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of copolymers based on poly(butylene terephthalate) and ethylene oxide‐poly(dimethylsiloxane)‐ethylene oxide

A series of thermoplastic elastomers based on ethylene oxide‐poly(dimethylsiloxane)‐ethylene oxide (EO‐PDMS‐EO), as the soft segment, and poly(butylene terephthalate) (PBT), as the hard segment, were synthesized by catalyzed two‐step, melt transesterification reaction of dimethyl terephthalate (DMT) with 1,4‐butanediol (BD) and α,ω‐dihydroxy‐(EO‐PDMS‐EO). Copolymers with a content of hard PBT segments between 40 and 90 mass % and a constant length of the soft EO‐PDMS‐EO segments were prepared. The siloxane prepolymer with hydrophilic terminal EO units was used to improve the miscibility between the polar comonomers, DMT and BD, and the nonpolar PDMS. The molecular structure and composition of the copolymers were determined by ¹H‐NMR spectroscopy, whereas the effectiveness of the incorporation of α,ω‐dihydroxy‐(EO‐PDMS‐EO) into the copolymer chains was verified by chloroform extraction. The effects of the structure and composition of the copolymers on the melting temperatures and the degree of crystallinity, as well as on the thermal degradation stability and some rheological properties, were studied. It was demonstrated that the degree of crystallinity, the melting and crystallization temperatures of the copolymers increased with increasing mass fraction of the PBT segments. The thermal stability of the copolymers was lower than that of PBT homopolymer, because of the presence of thermoliable ether bonds in the soft segments. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Studies of dimethylacrylates as crosslinkers for styrene

Styrene has been thermally copolymerized to low conversions with small quantities of ¹⁴C labelled ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate and poly(ethylene glycol) (mol. wt ≈ 400) dimethacrylate. The competition between intramolecular cyclization and intermolecular crosslinking has been examined via studies of intrinsic viscosity, variation of the proportion of the crosslinker reacted at both vinyl groups with conversion, and changes in the polydispersity ratio. These studies indicate that in the early stages of reaction, reductions in intrinsic viscosity are found to be maximum in PEG(400)DM copolymers, followed by TEGDM—styrene copolymers and least in the EGDM—styrene system. Also, in zero conversion extrapolation analysis, the fraction of the crosslinker reacted at both the ends increases with the molecular weight of the ethylene glycol unit. These observations imply that intramolecular cyclization is favoured by increasing the distance of separation between the two vinyl end groups of the dimethacrylate crosslinker. The increase in the fraction of the crosslinker reacted at both ends with conversion is found to be most rapid in the PEG(400)DM—styrene copolymers and least in the EGDM—styrene copolymers. The increase in polydispersity ratio with conversion is also found to fall into the same sequence. These observations suggest that intermolecular crosslinking is also favoured by increasing separation between the two vinyl groups of the crosslinker, i.e. the reactivity of the double bond attached to the polymer chain is greater both for cyclization and intermolecular reaction when the length of the poly(ethylene glycol) unit is increased.     

Rheological and physical properties of in situ composite based on liquid crystalline polymer and poly(ethylene 2,6‐naphthalate) blends

The in situ composites based on poly(ethylene 2,6‐naphthalate) (PEN) and liquid crystalline polymer (LCP) were investigated in terms of thermal, rheological, and mechanical properties, and morphology. Inclusion of LCP enhanced the crystallization rate and tensile modulus of the PEN matrix, although it decreased the tensile strength in the PEN‐rich phase. The orientation effect of this blend system was composition and spin draw ratio dependent, which was examined by Instron tensile test. Further, the addition of dibutyltindilaurate (DBTDL) as a reaction catalyst was found to increase the viscosity of the blends, enhance its adhesion between the dispersed LCP phases and matrix, and led to an increase of mechanical properties of two immiscible blends. Hence DBTDL is helpful in producing a reactive compatibilizer by reactive extrusion at the interface of this LCP reinforced polyester blend system. The optimum catalyst amount turned out to be about 500 ppm, when the reaction proceeded in the 75/25 PEN/LCP blend system. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2448–2456, 1999     

Structural features of poly(alkylene ether carbonate) diols and intermediates formed during their preparation

Capillary vapor-phase chromatography and carbon-13 nuclear magnetic resonance (NMR) have been used to elucidate the structure of poly(ethylene ether carbonate) diols and certain intermediates produced by the oligomerization of ethylene carbonate (EC) using monoethylene glycol (MEG) or diethylene glycol (DEG) as initiator and catalyzed by sodium stannate trihydrate. These diols are alternating copolymers of carbon dioxide and DEG which also contain smaller amounts of higher glycols as determined by comparing their ¹³C NMR spectra to the spectra of model compounds. Diethylene glycol is an important reaction intermediate and is present in steady-state concentrations. Although both 2-hydroxyethyl carbonate and 2-hydroxyethyl ether end groups are present at an intermediate stage in the reaction, only 2-hydroxyethyl ether end groups are present at high EC conversion. Molecular weight builds as a smooth function of conversion and time.