Linear oligoetherols and polyurethanes with carbazole ring

Reaction of 9‐(2‐chloroethyl)carbazole with excess of diethanolamine led to 5‐[2‐(carbazol‐9‐yl)ethyl]‐3‐azapentane‐1,5‐diol. The product is well soluble in ethylene and propylene oxides and reacted with them at temperature 60–90°C to give bifunctional oligoetherols with carbazole ring. Structure of these oligoetherols, their physical properties, and application for synthesis of linear polyurethanes were studied in detail. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Application of glycidol in synthesis of oligoetherols with perhydro‐1,3,5‐triazine ring

A new method of preparation of oligoetherols containing perhydro‐1,3,5‐triazine rings from isocyanuric acid and an excess of glycidol, alkylene carbonates, or oxiranes is presented. The course of reaction was studied at various molar ratios of glycidol to isocyanuric acid. The structure of the products was established, and some physical properties were measured. The oligoetherols were demonstrated to be useful substrates for polyurethane foams of enhanced thermal stability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The effect of the ring opening polymerization and chain spacing on the coefficient of thermal expansion and modulus of polyimide

The features of norbornene (NE) cross‐linked polyimide (PI) were investigated as the ratio of the norbornene monomer was varied. The coefficient of thermal expansion and modulus are important parameters of materials used in the microelectronic industry. Therefore, in this study, 5‐norbornene‐2, 3‐dicarboxylic acid (NE) was introduced as a crosslinking agent to increase the thermal stability at elevated temperatures. 4,4′‐Benzophenonetetracarboxylic dianhydride was utilized as a dianhydride and 4,4′‐diaminodiphenyl ether was introduced as a diamine monomer. By changing the ratio of each monomer, we were able to control the spacing of the chain and ring opening polymerization, which resulted in improved properties. Each sample was thermally cured which led to a ring opening mechanism of the norbornene through the reverse Diels‐Alder reaction. Thermal mechanical analysis was utilized to determine the coefficient of thermal expansion and dynamic mechanical analysis was used to determine the storage modulus (ε′) and loss modulus (ε″) of the PI film. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42607.     

One step synthesis and rapid ring‐opening polymerization of macrocyclic (arylene thioether ketone) oligomers

Well‐crystal macrocyclic (arylene thioether ketone) oligomers were synthesized under high dilution condition by the reaction of Na₂S with bis(4‐fluoro‐phenyl)‐methanone in 1‐methyl‐pyrrolidone (NMP). The oligomers were fully characterized by Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectra (MALDI‐TOF‐MS), high‐pressure liquid chromatography (HPLC), gel permeation chromatography (GPC), ¹H NMR, ¹³C‐NMR, and differential scanning calorimetry (DSC). According to DSC studies, uncatalyzed and rapid ring‐opening polymerization (ROP) of the oligomers took place instantly when they were heated to melting point. Extracted by dichloro‐methane, the obtained polymer neither loses any weight nor dissolves in boiling 1‐chloro‐ naphthalene. These facts indicated that there are no residual oligomers within the resultant polymer. The as‐prepared oligomers could be potentially used as high‐temperature hot‐melt adhesive at a high temperature > 350°C, and matrices for high‐performance composites and nanocomposites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 161–166, 2006     

Synthesis and study of the oligo(ether–ester)s based on butylene oxide

Unsaturated oligo(ether–ester) was prepared by ring‐opening polymerization of butylene oxide (BO) with glycidyl methacrylate (GMA) in the presence of cationic catalyst BF₃^?O(C₂H₅)₂. The effects of mol ratio of the initial components, amount of catalyst, temperature, and reaction times on the copolymerization reaction were examined. Oligo(ether–ester) were achieved in highest yield of 82% after reaction times of 4 h at 0°C. Synthesized copolymer was characterized using spectroscopic (¹H NMR and IR) and chemical analysis methods. The thermal degradation and softing points of oligo(ether–ester)‐styrene composites were studied. It is shown that crosslinking of the unsaturated oligo(ether–ester) with styrene takes place through the use of thermostable materials. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.     

Remarkable improvement of thermal stability of main‐chain benzoxazine oligomer by incorporating o‐norbornene as terminal functionality

A new main‐chain benzoxazine oligomer with o‐norbornene functionality as end groups has been designed and synthesized. As compared to traditional main‐chain type benzoxazine polymers, this benzoxazine oligomer with o‐norbornene terminal functionality can undergo further crosslinking polymerization after general ring‐opening polymerization of oxazine rings. Another main‐chain benzoxazine oligomer has also been designed based on the reaction of bisphenol‐A, 4,4′‐diaminodiphenylmethane, paraformaldehyde, and phenol for comparison. The structure of the synthesized oligomers is confirmed by ¹H nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy (FTIR). The molecular weight has been determined by using gel permeation chromatography (GPC). The benzoxazine oligomer containing o‐norbornene functionality can polymerize with multiple polymerization mechanisms rather than the single mechanism common to traditional 1,3‐benzoxazine resins. The polymerization mechanisms are monitored by in situ FTIR and differential scanning calorimetry (DSC). Moreover, the thermoset derived from the benzoxazine oligomer containing o‐norbornene functionality exhibits high thermal stability with the transition temperature of 360 °C and a high T_d5 of 404 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45408.     

Synthesis of a novel benzoxazine precursor containing phenol hydroxyl groups and its polymer

A novel benzoxazine precursor containing phenol hydroxyl groups was synthesized from bisphenol A, 4,4′‐diaminodiphenyl methane, and formaldehyde with a molar ratio of 2:1:4. The benzoxazine precursor was characterized with Fourier transform infrared, proton nuclear magnetic resonance, and size exclusion chromatography. The curing reaction was monitored by the gel time, differential scanning calorimetry, and Fourier transform infrared. The obtained polybenzoxazine showed high thermal stability and a high glass‐transition temperature. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A novel polybenzoxazine containing styrylpyridine structure via the Knoevenagel reaction

In this article, a kind of styrylpyridine‐containing polybenzoxazine was obtained via the Knoevenagel reaction between benzaldehyde and methylpyridine groups. The benzoxazine monomer (MPBC) containing the benzaldehyde and methylpyridine groups was synthesized firstly and its structure was characterized by Fourier transform infrared (FTIR) spectra, ¹H NMR and ¹³C NMR. With the aid of differential scanning calorimetry, FTIR, and photoluminescent tests, the interesting curing behaviors were probed. The results showed that the ring‐opening polymerization occurred at lower temperature, and the Knoevenagel reaction further took place at elevated temperature. The amine and phenol moieties were bonded together to form the styrylpyridine structure. Due to these special crosslinking structures, the corresponding polybenzoxazine exhibited excellent thermal stability, and had a special high char yield of 74.5%. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40823.     

Improved synthesis and properties of hydroxyl‐terminated liquid fluorosilicone

The synthesis of hydroxyl‐terminated poly(trifluoropropylmethyl)siloxane (PTFPMS‐OH) by anionic ring‐opening polymerization of 1,3,5‐tris(trifluoropropylmethyl)cyclotrisiloxane (D₃F) was studied in bulk using potassium hydroxide as an initiator in the presence of several reaction stabilizers. The promoting effect of the reaction stabilizers for the polymerization of D₃F was investigated by GPC and NMR analyses. Results showed that the selected reaction stabilizers exhibited a significant promoting effect. This new process of polymerization produced well‐defined α,ω‐dihydroxylated polysiloxane in very high yields. The addition of reaction stabilizers could almost completely suppress back‐biting reactions during the polymerization. It was found that there lies an exponential decay relationship between the molecular weight of PTFPMS‐OH and amount of end‐capping agent. Thus, by adjusting the reaction conditions strictly, the molecular weight of the fluorosilicone could be controlled accurately, and meanwhile a broad “terminate window” could be implemented. Thermogravimetic (TG) analysis indicated that PTFPMS‐OH could be used in a wide range of operational temperatures. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43220.     

Online monitoring of reaction temperature during cationic ring opening polymerization of epichlorohydrin in presence of BF3 and 1,4‐butanediol

This work introduces cationic ring opening polymerization of polyepichlorohydrin (PECH) produced under various reaction conditions (set temperature: ?10 to 40°C, [C]/[I] ratio: 0.1–1, monomer feed rate: 1–4 mL/min). In addition, a correlation between the exothermic reaction temperature and the performance of the PECH was obtained by utilizing a reaction temperature monitoring system, GPC, ¹H‐NMR, and FTIR. During the polymerization, an induction period which affects the polydispersity was observed below 10°C. At lower temperatures and lower [C]/[I] ratios, a higher induction period was observed. The monomer feed rate did not affect the induction period but it highly affected the polydispersity when the induction period occurred. The total molecular weight of PECH increased with decreasing set temperature even though the amount of low molecular weight cyclic oligomer increased. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39912.     

Biodegradable block copolymers with poly(ethylene oxide) and poly(glycolic acid‐valine) blocks

Biodegradable ABA triblock copolymers with poly(ethylene oxide) and poly(glycolic acid‐valine) blocks were synthesized via ring‐opening polymerization of cyclo(glycolic acid‐valine) using Ca‐alcoholates of hydroxytelechelic PEO as the initiator. The L‐valine residue racemized during copolymerization of cyclo(glycolic acid‐valine). The crystallization of the block copolymers decreases with decreasing PEO content in the triblock copolymers and with increasing length of the poly(glycolic acid‐valine) block. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2916–2919, 2002     

Polyurethane foams with 1,3‐pyrimidine ring

Attempts of obtaining of polyurethane foams using polyetherols with 1,3‐pyrimidine ring (obtained in reactions of 6‐aminouracil with oxiranes) are reported. Properties of the foams are investigated, especially their thermal stability. The foams show an improved thermal stability up to 200°C for a long time. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and properties of novel hybrid resins based on acetylene‐functional benzoxazine and polyvinylsilazane

A serial of addition‐curable hybrid resins for resin matrix of advanced composites are prepared by thermal prepolymerization between acetylene‐functional benzoxazine(BZ) and polyvinylsilazane(PSN) with various weight ratios. Processing capability of BZ‐PSN resin is investigated by measuring viscosity. Cure behavior is investigated by differential scanning calorimetry (DSC) and Fourier transform infrared (FT‐IR) spectra. Thermal property of cured BZ‐PSN resin is investigated by Thermogravimetric analysis (TGA) and Dynamic mechanical analysis (DMA). BZ‐PSN resin shows a low viscosity of 40–180 mPa·s between 60 and 90°C, and maintains the low viscosity for 6 h, indicating that the resin is suitable for resin transfer molding (RTM) process to fabricate composites. DSC results show that BZ‐PSN resin can be cured completely at about 250°C without adding any other curing additives. FT‐IR shows the reaction between BZ and PSN take place. TGA shows that thermal stability of cured BZ‐PSN resin is increased with the content of polyvinylsilazane increasing both in nitrogen and in air. DMA shows cured hybrid resins have excellent thermal properties. The excellent processability and thermal properties suggest that BZ‐PSN resin is a promising candidate for resin matrix of advanced composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3794–3799, 2013     

Polyester resins with carbazole ring

3‐(9‐Carbazolyl)propane‐1,2‐diol was obtained in the reaction of 9‐(2,3‐epoxypropyl)carbazole with water. The obtained diol was further used for modification of unsaturated polyester resin to produce enhanced thermal and heat resistance in comparison with classic resins. The properties of polyesters and polyester resins modified with 3‐(9‐carbazolyl)propane‐1,2‐diol were studied in detail. When 3‐(9‐carbazolyl)propane‐1,2‐diol is used instead of propylene glycol the unsaturated polyester resins possess enhanced thermal stability.© 2013 Society of Chemical Industry     

Hydroxyalkylation of barbituric acid. II. Synthesis of polyetherols with pyrimidine ring

The route of synthesis of new polyetherols with pyrimidine ring from barbituric acid (BA) was presented. The polyetherols were obtained in two steps: synthesis of hydroxymethyl derivative of BA followed by reaction of the latter with neat ethylene or propylene oxides. Physical properties of the products and preliminary application for fabrication of thermal stability polyurethane foams were determined. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

In Situ synthesis of multiblock copolymers of poly(ϵ‐caprolactone) with different poly(ether diols) based polyurethane by reactive extrusion

Polyurethanes with multiblock copolymers of poly(?‐caprolactone) (PCL) and poly(tetramethylene oxide) glycol (PTMG) or poly(ethylene glycol) (PEG) as a soft segment were synthesized in situ via reactive extrusion from ?‐caprolactone (CL) and 4,4′‐diphenylmethane diisocyanate (MDI). The titanium alkoxide mixture generated from an ester‐exchange reaction between titanium propoxide [Ti(OPr)₄], and excessive PTMG or PEG was used as an initiator and catalyst. Compared to the reported fabrication of polycaprolactone‐based polyurethane (PCLU), the in situ reactive extrusion preparation not only explored a new rapid route for the fabrication of PCLU but also offered a simplified, controllable approach for the production of PCLU in a successive mass scale. A series of PTMG–PCLUs and PEG–PCLUs with different PCL block‐average degrees of polymerization (DP_n's) were prepared by only an adjustment of the relative concentration of CL in the reaction system, with a certain constant molar ratio of MDI to titanium alkoxide. ¹H‐NMR, gel permeation chromatography, and differential scanning calorimetry results indicate that all of the CL monomers were converted in the polymerization, and the molecular weight of the copolymers was about 8 × 10⁴ g/mol with a polydispersity index of approximate 2.4. With an increase in the PCL block‐average DP_n in PTMG–PCLU from 25 to 40, the tensile strength increased from 16.5 to 22.7 MPa, and the melting point increased from 46.1 to 49.5°C. It was also verified by PEG–PCLU prepared with organic Ti of lowered content in the initiator mixture that the mechanical properties could be greatly affected and dropped with decreasing content of organic Ti in the initiator mixture. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Supercritical fluid extraction of cyclic oligomers from depolymerizing PBT

Cyclic oligomers of polyester show great potential for a reaction‐injection‐molding process, because of their initial low viscosity and rapid ring‐opening polymerization at low temperatures (180°C) without exothermic reaction or condensates. In this work, we report the synthesis of cyclic oligo(butylene terephthalate) (COBT) from linear poly(butylene terephthalate) by a formation–extraction process employing supercritical fluids (SCF) CO₂ and pentane at T = 230°C and P = 250 bar. Following this, depressurization of SCF leads to easy recovery of the COBTs. When compared with SCF CO₂, SCF pentane is found to be an attractive solvent because of its higher solubilizing capacity (0.8 mg COBT dimer/g pentane) for the COBTs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4487–4492, 2006     

Synthesis of polylactide with varying molecular weight and aliphatic content: Effect on moisture sorption

Polylactide (PLA) is a bio‐based, biodegradable polymer, which is derived from lactic acid and has numerous potential applications, some of which are limited by its moisture barrier and thermal properties. Prior studies have been inconsistent about how moisture sorption in PLA varies with crystallinity and molecular weight. This research is a systematic study of how moisture sorption in PLA depends on molecular weight and aliphatic content via end‐group modification. PLA with varying aliphatic content was synthesized by ring‐opening polymerization of L ‐lactide initiated with different long‐chain aliphatic alcohols. The terminating end groups were also modified from hydroxyl to acetoxy to eliminate hydrophilic end groups. Molecular weight was controlled by varying the ratio of L ‐lactide monomer to alcohol initiator, and triethylaluminum was used as the catalyst for precise control over molecular weight. The molecular weight and end‐group compositions were verified by gel permeation chromatography and nuclear magnetic resonance. Moisture sorption of the modified PLA samples was measured with a quartz crystal microbalance. Quartz crystal microbalance experiments revealed that both molecular weight and aliphatic content contributed to the sorption properties of PLA. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of nanocomposites based on polylactides tethered with polyhedral oligomeric silsesquioxane

A series of polylactides tethered with polyhedral oligomeric silsesquioxane (POSS–PLAs) were synthesized via the ring‐opening polymerization of L ‐lactide with 3‐hydroxypropylheptaisobutyl polyhedral oligomeric silsesquioxane (3‐hydroxypropylheptaisobutyl POSS) at a concentration of 0.02–2.00 mol % in the presence of a stannous(II) octoate catalyst. 1 H‐NMR spectra and a composition analysis of the POSS–PLA hybrids confirmed that 3‐hydroxypropylheptaisobutyl POSS served as an initiator for L ‐lactide in the ring‐opening polymerization. X‐ray diffraction patterns evidenced that polyhedral oligomeric silsesquioxane (POSS) molecules of POSS–PLA hybrids were well dispersed without the formation of their crystalline aggregates. The POSS–PLA hybrid with 0.50 mol % POSS content was solution‐blended with a neat polylactide (PLA) homopolymer to obtain PLA/POSS–PLA nanocomposites with various POSS–PLA contents of 1–30 wt %. The X‐ray diffraction results of the PLA/POSS–PLA nanocomposites demonstrated that the POSS–PLA was well dispersed in the neat PLA matrix. The thermal and thermooxidative degradation properties of the nanocomposites were found to be improved at POSS–PLA contents of 1–20 wt %, compared to the neat PLA. The crystallization rates and crystallinities of the PLA/POSS–PLA nanocomposites were faster and higher, respectively, with increasing POSS–PLA content because of the nucleation effect of the POSS molecules in the neat PLA matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and applications of oligoetherols with perhydro‐1,3,5‐triazine ring and boron

A new method of preparation of oligoetherols containing perhydro‐1,3,5‐triazine rings and boron atoms is presented. The oligoetherols were obtained in the reaction of 1,3,5‐tris(2‐hydroxyethyl) isocyanurate with boric acid followed by reaction with alkylene carbonates. The structure and physical properties of the products render them good candidate for preparing the polyurethane foams. The foams were obtained and their properties were compared with those synthesized from isocyanuric acid and alkylene carbonates. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013