Cationic copolymerization of diglycidyl ether of bisphenol A with phthalide or 3,3′‐diphtalide catalyzed by lanthanide triflates

Mixtures of the diglycidylether of bisphenol A (DGEBA) and phthalide (PT) or 3,3′‐diphthalide (DPT) were cured using ytterbium or lanthanum triflate as catalyst. The curing was studied by differential scanning calorimetry (DSC) and Fourier transform infrared in attenuated‐total‐reflection mode (FTIR/ATR). FTIR/ATR was used to monitor the competitive reactive processes and quantify the evolution of the epoxide and lactone groups. The T_g of the crosslinked materials increased when the proportion of lactone in the curing mixture decreased. The kinetics was studied with DSC experiments and isoconversional procedures. The differences in the reactivity of the systems were related to the Lewis acidity of the lanthanide salt used as initiator. The increase in the proportion of lactone leads to an increase in the reaction rate. The shrinkage was determined from the densities before and after curing and its evolution was studied by thermomechanical analysis. The materials obtained were characterized by thermogravimetry and dynamic mechanical thermal analysis. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1711–1721, 2006     

Cationic copolymerization of cycloaliphatic epoxy resin with a spirobislactone with lanthanum triflate as initiator: I. Characterization and shrinkage

3,4‐Epoxycyclohexylmethyl 3,4‐epoxycyclohexane carboxylate (ECH) was cured with different proportions of 1,6‐dioxaspiro [4,4]nonane‐2,7‐dione (s(γ‐BL)) using lanthanum triflate as a catalyst. The shrinkage undergone during curing was monitored by means of thermomechanical analysis (TMA) in isothermal experiments. Fourier transform infrared spectroscopy in attenuated‐total‐reflection mode (FTIR/ATR) was used to study the evolution of lactone, epoxide, and intermediate spiroorthoester (SOE) groups to identify the different reactions that take place during the curing process. DSC was used to study the thermal characteristics of the curing process and to assess the glass‐transition temperature (T_g) of the cured material. The dynamic mechanical properties of the cured material were determined based on the data obtained by DMTA. An increase in the proportion of s(γ‐BL) led to a decrease in the gelation time and the shrinkage after gelation. By combining the data obtained by TMA and FTIR/ATR, it was also possible to identify the reactive processes responsible for the shrinkage. It was observed that an increase in the proportion of s(γ‐BL) also increases the speed of the curing process and modifies the structure of the material, thus giving rise to more flexible materials. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3421–3432, 2005     

Crosslinking study of mixtures of DGEBA and 1,3‐dioxan‐2‐one catalyzed by lanthanide triflates

Ytterbium and lanthanum triflates were used as catalysts to cure diglycidylether of bisphenol A with different proportions of 1,3‐dioxan‐2‐one. The curing was studied by differential scanning calorimetry (DSC) and Fourier transform infrared in the attenuated‐total‐reflection mode (FTIR/ATR). FTIR/ATR was used to monitor the competitive reactive processes and to quantify the evolution of the groups involved in the curing process. We observed the formation of a five‐membered cyclic carbonate that remains unreacted at the chain ends, because of an equilibrium process between the spiroorthocarbonates that had formed as intermediate species. The kinetics were studied by DSC experiments and analyzed with isoconversional procedures. The system catalyzed by ytterbium triflate had a higher curing rate. Thermogravimetric analysis and dynamic mechanical thermal analysis experiments were used to evaluate the properties of the materials obtained. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5799–5813, 2005     

Structural and phenomenological study on the cationic curing of mixtures of epoxy resin and 5,5‐dimethyl‐1,3‐dioxane‐2‐one

Ytterbium and lanthanum triflates were used as initiators to cure a mixture of diglycidylether of bisphenol A (DGEBA) and 5,5‐dimethyl‐1,3‐dioxane‐2‐one (DMTMC). The evolution of the curing was studied by differential scanning calorimetry (DSC) and Fourier transform infrared in the attenuated‐total‐reflection mode (FTIR/ATR). FTIR/ATR was used to monitor the competitive reactive processes and to quantify the evolution of the groups involved in the curing process. We observed the formation of a five‐membered cyclic carbonate, which remains unreacted at the chain ends because of an equilibrium process between the spiroortho carbonates that had formed as intermediate species and also the loss of CO₂, which was quantified by thermogravimetry. The kinetics were studied by DSC and analyzed by isoconversional procedures. Thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA) experiments were used to evaluate the properties of the thermosets obtained. The phenomenological changes that take place during curing were studied and represented in a time‐temperature‐transformation (TTT) diagram. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4546–4558, 2006     

Novel thermosets obtained by UV‐induced cationic copolymerization of DGEBA with an spirobislactone

The photocuring process of the diglycidyl ether of bisphenol A (DGEBA) with the bislactone 1,6‐dioxaspiro[4,4]nonane‐2,7‐dione (s(γ‐BL)) was studied. Triarylsulfonium hexafluoroantimonate was employed as photoinitiator. FTIR/ATR was used to study the evolution of epoxy, lactone, and intermediate spiroorthoester groups to identify the different reactions that take place during the photocuring process. Photo‐DSC and DSC were used to study the thermal evolution of the photocuring process and to assess the T_g of the fully cured material. Thermogravimetric analysis (TGA) was used to determine the thermal stability of the fully cured material. The thermomechanical properties of the materials were investigated using dynamic mechanical‐thermal analysis. Shrinkage undergone during photocuring and gelation was studied with TMA. A strong influence of the photocuring temperature on the photocuring process of the DGEBA‐ s(γ‐BL) system was observed. Differences in the reactivity of the different species were observed with respect to the thermally cured system using ytterbium triflate as cationic thermal initiator. As a consequence, photocured materials exhibited a superior thermal stability and lower flexibility. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5446–5458, 2007     

N,N‐dimethylaminopyridine as initiator in the copolymerization of diglycidylether of bisphenol A with six‐membered cyclic carbonates

N,N‐Dimethylaminopyridine (DMAP) was used as initiator to cure mixtures of diglycidylether of bisphenol A (DGEBA) and 1,3‐dioxan‐2‐one (TMC) or 5,5‐dimethyl‐1,3‐dioxan‐2‐one (DMTMC). The curing was studied by differential scanning calorimetry (DSC) and Fourier transform infrared in the attenuated‐total‐reflection mode (FTIR/ATR). FTIR/ATR was used to monitor the competitive reactive processes and to quantify the evolution of the groups involved in the curing. We observed the formation of five‐membered cyclic carbonates and anionic carbonate groups that remain unreacted at the chain ends. The formation of these groups was explained by the attack of the anionic propagation species on the methylene carbon of the carbonate group, which leads to an alkyl‐oxygen rupture. By performing the cure in the thermobalance we could evaluate the loss of CO₂ produced in the samples containing carbonates. The kinetics were studied by DSC and analyzed with isoconversional procedures. The addition of carbonates slows down the curing rate. Thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA) experiments were used to evaluate the properties of the materials obtained. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2873–2882, 2006     

Morphological change of poly (ε‐caprolactone) with a wide range of molecular weight via formation of inclusion complex with α‐cyclodextrin

The effect of molecular weight of poly(ε‐caprolactone) (PCL) on the formation and stability of inclusion complexes (ICs) between α‐cyclodextrin (α‐CD) and PCL was investigated by FTIR, WAXD, and DSC measurements. ICs between α‐CD and PCLs with a wide range of number‐average molecular weight, M_n = 1.21 × 10⁴ – 1.79 × 10⁵, were prepared by mixing the aqueous solution of CD and acetone solution of PCL followed by stirring at 60 °C for 1h and at the room temperature for 1 day. FTIR, WAXD, and DSC measurement showed the PCL chains were included into the α‐CD cavity, and the crystallization of PCL was suppressed in the α‐CD cavity. Stoichiometry and yield of each IC varied with the molecular weight of guest PCL, and the effect of IC formation on the crystallization behaviour of guest polymer decreased with the increase of molecular weight of guest polymer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1433–1440, 2005     

Fractionation of ethylene/1‐pentene copolymers using a combination of SEC‐FTIR and SEC‐HPer DSC

The short chain branching distribution (SCBD) and thermal properties of ethylene/1‐pentene copolymers were studied using SEC‐FTIR and SEC‐HPer DSC. The copolymers, synthesized with Cp₂ZrCl₂/MAO, were fractionated using size exclusion chromatography (SEC). The infrared analysis of the fractions showed that the copolymers had—on average—higher 1‐pentene concentration in the low molecular weight range. Furthermore, the thermal properties of the SEC deposits of these copolymers on a Germanium disc were studied using high performance differential scanning calorimetry (HPer DSC). Single SEC separations were used to accumulate fractions in the microgram range that were directly analyzed with regard to their thermal properties, thus allowing us to study SCBD as well as thermal behavior simultaneously. When these fractions (with masses ranging from 10–80 μg) were analyzed using HPer DSC, good melting and crystallization temperature distributions were obtained, proving that HPer DSC can be used as a complementary method to SEC‐FTIR. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2956–2965, 2007     

Pt‐catalyzed chemical modification of α,ω‐bis(hydrido)polydimethylsiloxanes and copoly(methylhydridosiloxane/dimethylsiloxane) with vinylheptaphenylcyclotetrasiloxane

Pt‐catalyzed hydrosilylation between vinylheptaphenylcyclotetrasiloxane and a series of α,ω‐bis(hydrido)polydimethylsiloxanes and copoly(methylhydridosiloxane/dimethylsiloxane) was used to prepare chemically modified materials. These modified polymers were characterized by IR, UV, and ¹H, ¹³C, and ²⁹Si NMR spectroscopy and gel permeation chromatography (GPC). The molecular weights, determined by GPC, UV, and NMR end‐group analysis, showed the anticipated increases. The thermal properties of the polymers were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The crystallinity, determined by DSC, was either reduced or completely eliminated for the modified polymers. The thermal stabilities, measured in both air and nitrogen by TGA, were slightly higher than the thermal stability of α,ω‐bis(trimethylsiloxy)polydimethylsiloxane. Significantly increased bulk viscosities were observed for all the modified polymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3007‐3017, 2005     

New poly(ether‐ester) thermosets obtained by cationic curing of DGEBA and 7,7‐dimethyl‐6,8‐dioxaspiro[3.5] nonane‐5,9‐dione with several Lewis acids as initiators

Scandium, ytterbium, and lanthanum triflates and boron trifluoride monoethylamine were used as cationic initiators to cure a mixture 2:1 (mol/mol) of diglycidylether of bisphenol A (DGEBA) and 7,7‐dimethyl‐6,8‐dioxaspiro[3.5]nonane‐5,9‐dione (MCB). The evolution of the epoxy and lactone during curing and the linear ester groups in the final materials were evaluated by Fourier Transform Infrared in the attenuated‐total‐reflection mode. The kinetic parameters of the curing process were calculated from DSC analysis applying isoconversional procedures. The shrinkage on curing and the thermal degradability of the materials on varying the initiator used were evaluated. The expandable character of MCB was confirmed. The materials obtained were more degradable than conventional epoxy resins due to the tertiary ester groups incorporated in the network by copolymerization. © 2008 Wiley Periodicals, Inc J Polym Sci Part A: Polym Chem 46: 1229–1239, 2008     

New thermosets obtained by the cationic copolymerization of diglycidyl ether of bisphenol A with γ‐caprolactone with an improvement in the shrinkage. I. Study of the chemical processes and physical characteristics

Diglycidyl ether of bisphenol A was cured with different proportions of γ‐caprolactone with ytterbium triflate as an initiator. The curing was studied by means of differential scanning calorimetry and Fourier transform infrared in the attenuated total reflection mode. The latter was used to monitor the competitive reactive processes and to quantify the conversions of the epoxide, lactone, and intermediate spiroorthoester groups. A partial depolymerization process from the cured material to free γ‐caprolactone was also identified. The formation of a stable carbocation and the coordinative capability of ytterbium triflate were the reasons for this unexpected process. The thermal and dynamic mechanical properties of the cured materials were determined with differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical thermal analysis. An increase in the proportion of γ‐caprolactone resulted in an increased curing rate, a decrease in the shrinkage after gelation, and a significant decrease in the glass transition temperature. The introduction of ester linkages into the three‐dimensional structure led to more thermally degradable thermosets. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1968–1979, 2007     

Studies on poly(ε‐caprolactone)/thiodiphenol blends: The specific interaction and the thermal and dynamic mechanical properties

The effects of several low molecular weight compounds with hydroxyl groups on the physical properties of poly(ε‐caprolactone) (PCL) were investigated by Fourier transform infrared (FTIR) spectroscopy and high‐resolution solid‐state ¹³C NMR. PCL and 4,4′‐thiodiphenol (TDP) interact through strong intermolecular hydrogen bonds and form hydrogen‐bonded networks in the blends at an appropriate TDP content. The thermal and dynamic mechanical properties of PCL/TDP blends were investigated by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis, respectively. The melting point of PCL decreased, whereas both the glass‐transition temperature and the loss tangent tan δ of the blend increased with an increase in TDP content. The addition of 40 wt % TDP changed PCL from a semicrystalline polymer in the pure state to a fully amorphous elastomer. The molecules of TDP lost their crystallizability in the blends with TDP contents not greater than 40 wt %. In addition to TDP, three other PCL blend systems with low molecular weight additives containing two hydroxyl groups, 1,4‐dihydroxybenzene, 1,4‐di‐(2‐hydroxyethoxy) benzene, and 1,6‐hexanediol, were also investigated with FTIR and DSC, and the effects of the chemical structure of the additives on the morphology and thermal properties are discussed. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1848–1859, 2000     

Synthesis and characterization of biodegradable triblock copolymers based on bacterial poly[(R)‐3‐hydroxybutyrate] by atom transfer radical polymerization

Biodegradable poly(tert‐butyl acrylate)–poly[(R)‐3‐hydroxybutyrate]–poly (tert‐butyl acrylate) triblock copolymers based on bacterial poly[(R)‐3‐hydroxybutyrate] (PHB) were synthesized by atom transfer radical polymerization. The chain architectures of the triblock copolymers were confirmed by ¹H NMR and ¹³C NMR spectra. Gel permeation chromatography analysis was used to estimate the molecular weight characteristics and lengths of the PHB and poly(tert‐butyl acrylate) blocks of the copolymers. The thermal properties of the copolymers were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA showed that the triblock copolymers underwent stepwise thermal degradation and had better thermal stability than their respective homopolymers, whereas DSC analyses showed that a microphase‐separation structure was formed only in the triblock copolymers with the longer PHB block. As a similar result, from wide‐angle X‐ray diffraction experimentation, the crystalline phase of PHB could not be seen evidently in the triblock copolymers with the shorter PHB block. The enzymatic hydrolysis of the copolymer films was carried at 37 °C and pH 7.4 in a potassium phosphate buffer with an extracellular PHB depolymerase from Penicillum sp. The biodegradability of the triblock copolymers increased with an increase in the PHB block content. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4857–4869, 2005     

Synthesis and characterization of poly(higher‐α‐olefin)s with a nickel(α‐diimine)/methylaluminoxane catalyst system: Effect of chain running on the polymer properties

Homopolymerization of octadecene‐1 at different reaction conditions has been studied. Significant chain running can be seen at higher polymerization temperatures. Interestingly, insertion of octadecene‐1 into a sterically hindered nickel‐cation/carbon (secondary) bond is observed. The microstructure of the polymer was established using NMR spectroscopy. The effects of chain running on polymer melting, crystallization behavior, and dynamic mechanical thermal properties were studied using DSC and DMTA. The extent of chain running (i.e., 2,ω‐, 1,ω‐enchainments) decreases with an increase in the carbon number of α‐olefins. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 191–210, 2007     

New associative EHEC‐g‐PAam copolymers: Their syntheses,characterization, and rheological behavior

The syntheses and rheological behavior of ethyl hydroxyethyl cellulose (EHEC)‐based graft‐copolymers were studied. Copolymers were prepared by grafting EHEC with acrylamide (Aam) via reversible addition fragmentation chain transfer (RAFT) polymerization. Hydroxyl groups of EHEC were esterified with a carboxylic acid functional chain transfer agent (CTA) to prepare EHEC‐macroCTAs with different degrees of substitution. EHEC‐macroCTAs were characterized by ATR‐FTIR, ¹³C NMR, and SEC, and elemental analysis was used to quantify the degree of CTA substitution. EHEC‐macroCTAs with different degrees of substitution were copolymerized with acrylamide by “grafting from” technique. Formation of new cellulose‐based copolymers was comprehensively confirmed by ¹H NMR, ATR‐FTIR, and SEC measurements. Further, the associations of EHEC‐g‐PAam copolymers in water were studied at various concentrations and temperatures by means of UV–vis spectroscopy, fluorescence spectroscopy, and rheological measurements. The results indicate that copolymers have both intra and intermolecular association in water depending on the amount of grafts. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1869–1879, 2009     

Poly(N‐phenylmaleimide‐co‐acrylic acid)–copper(II) and poly(N‐phenylmaleimide‐co‐acrylic acid)–cobalt(II) complexes: Synthesis,characterization, and thermal behavior

The free‐radical copolymerization of N‐phenylmaleimide (N‐PhMI) with acrylic acid was studied in the range of 25–75 mol % in the feed. The interactions of these copolymers with Cu(II) and Co(II) ions were investigated as a function of the pH and copolymer composition by the use of the ultrafiltration technique. The maximum retention capacity of the copolymers for Co(II) and Cu(II) ions varied from 200 to 250 mg/g and from 210 to 300 mg/g, respectively. The copolymers and polymer–metal complexes of divalent transition‐metal ions were characterized by elemental analysis, Fourier transform infrared, ¹H NMR spectroscopy, and cyclic voltammetry. The thermal behavior was investigated with differential scanning calorimetry (DSC) and thermogravimetry (TG). The TG and DSC measurements showed an increase in the glass‐transition temperature (T_g) and the thermal stability with an increase in the N‐PhMI concentration in the copolymers. T_g of poly(N‐PhMI‐co‐AA) with copolymer composition 46.5:53.5 mol % was found at 251 °C, and it decreased when the complexes of Co(II) and Cu(II) at pHs 3–7 were formed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4933–4941, 2005     

FTIR, 13C NMR,and GPC analysis of high‐propylene content co‐ and terpolymers with ethylene and higher α‐olefins synthesized with EtInd2ZrCl2/MAO

This article reports the results of propylene/α‐olefin copolymerization and propylene/ethylene/α‐olefin terpolymerization using low concentrations (less than 5 mol %) of long α‐olefins such as 1‐octene, 1‐decene, and 1‐dodecene. Kinetics data are presented and discussed. The highest activity was found with the longest α‐olefin studied (1‐dodecene). A possible explanation is proposed for this and other characteristics of the polymers obtained. The effect of low‐ethylene contents (4 mol % in the gas phase) on the copolymerization of propylene/α‐olefins was also examined. The polymers synthesized were characterized by ¹³C NMR, gel permeation chromatography, DSC, Fourier transform infrared spectroscopy, and wide‐angle X‐ray scattering. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2005–2018, 2001     

Microwave‐assisted synthesis of a novel phosphorus‐containing spiroorthoester,characterization and cationic polymerization

A new phosphorus‐containing spiroorthoester, (1,4,6‐trioxaspiro [4,4] nonan‐2‐yl)‐methyl 3‐[10‐(9,10‐dihydro‐9‐oxa‐9‐phosphaphenanthrene‐10‐oxide)]‐propanoate (SOE‐P), was synthesized under microwave irradiation with a short reaction time (1 h), because classical thermal heating did not lead to the desired product. The structure of the new monomer was confirmed by ¹H, ¹³C, and ³¹P. SOE‐P was homopolymerized and copolymerized with phenylglycidyl ether with ytterbium triflate as a cationic initiator in DSC experiments. These reactions were monitored by FTIR/ATR, and the formation of poly(ether‐ester)s with a pendant bulky phosphorylated group was shown. © 2006Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4722–4730, 2006     

Micro ATR‐FTIR study of the hydration state of poly(N‐tert‐butylacrylamide‐co‐acrylamide) copolymers during phase transition in aqueous media and in the mixture of water–methanol

Coil‐globule transition of poly(N‐tert‐butylacrylamide‐co‐acrylamide) P(NTBAM‐co‐AM) copolymers is investigated in the aqueous solution and in the mixture of water–methanol by micro ATR‐FTIR spectroscopy technique. In this study the microstructure and its changes in the hydration states of the distinct groups of these copolymers are investigated by micro ATR/FTIR technique. The results showed that by heating the solution above the LCST hydrogen bonding between C?O and water was decreased but the hydrogen bonding between polymeric chains increased, which prove the aggregation of polymer chain during phase separation. The chemical shifts of IR bands are also studied in the mixture of water–methanol. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 356–363, 2010     

Study of hydrogen bonding and thermal properties of polybenzoxazine and poly‐(ε‐caprolactone) blends

The thermal properties of physical blends containing benzoxazine monomer and polycaprolactone (PCL) were monitored by DSC and Fourier transform infrared spectroscopy (FTIR). The ring‐opening reaction and subsequent polymerization reaction of the benzoxazine were facilitated significantly by the presence of a PCL modifier. Hydrogen‐bond formation between the hydroxyl groups of polybenzoxazine and the carbonyl groups of PCL was evident from the FTIR spectra. Only one glass‐transition temperture (T_g) value was found in the composition range investigated, and the T_g value of the resulting blend appeared to be higher in the blend with a greater amount of PCL. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 736–749, 2001