A high temperature polymer of phthalonitrile‐substituted phosphazene with low melting point and good thermal stability

A phthalonitrile‐substituted phosphonitrilic monomer has been synthesized from phosphonitrilic chloride trimer and then polymerized with addition of 4‐(hydroxylphenoxy)phthalonitrile (HPPN). The chemical structures of the phosphonitrilic monomer and polymer were characterized by Fourier Transform Infrared spectroscopy (FT‐IR) and proton Nuclear Magnetic Resonance spectroscopy (¹H NMR). Curing behaviors and thermal stabilities of the polymer were investigated through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Analysis showed that the monomer has large processing temperature window and good thermal stability. Apparent activation energy, initial curing temperature (T_i), curing temperature (T_p), and termination curing temperature (T_f) of the phosphonitrilic polymer were explored. Dynamic mechanical analysis (DMA), glass transition temperature (T_g) were studied, and limiting oxygen index (LOI) were estimated from the van Krevelen equation, which indicates the polymer process high modulus and good flame retardance. Micro‐scale combustion calorimetry (MCC) was also used for evaluating the flammability of the polymers. Postcuring effects were explored, showing excellent thermal and mechanical properties with postcuring. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42606.     

Tailoring terpenoid plasma polymer properties by controlling the substrate temperature during PECVD

Polymers derived from natural, minimally‐processed materials have recently emerged as a more sustainable alternative to synthetic polymers, with promising applications in biocompatible and biodegradable devices. Plasma‐enhanced deposition is well‐suited to one‐step, fast, and efficient synthesis of highly crosslinked inert polymers directly from natural resources, however, fabrication of biologically active polymers remains a challenge. Plasma processing parameters influence the properties such as surface energy, roughness, morphology, and chemical composition of deposited polymers and thus their final applications. This article reports on the important role of substrate temperature (T_S) in the chemical composition, wettability, refractive index, and crosslinking density of plasma polymers derived from terpenoids. Experiments are conducted as a function of deposition power P_d, and substrate temperature, T_S. T_S varied from 40 to 280 °C and is externally controlled. Atomic force microscopy analysis reveals the change in deposition mechanism attributed to shadowing effect at higher T_S and P_d. Increase in band gap (E_g) with high T_s deposition for terpenoid based plasma polymers is observed. Swelling behavior analyzed by in situ ellipsometry affirms the enhanced crosslink density with increasing deposition rate. Fourier transform infrared analysis exhibits the formation of additional chemical moieties with increasing T_S. Increase in deposition rate with increasing T_S at higher P_d supports the theory of direct incorporation of depositing particles as dominant mechanism of plasma polymerization in this study. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45771.     

Europium‐containing cholesteric liquid crystalline polymers in the side chain

Europium‐containing cholesteric liquid crystalline polymers were graft copolymerized using poly(methylhydrogeno)siloxane, cholesteryl 4‐(allyloxy)benzoate (M₁), cholesteryl acrylate (M₂), and a europium complexes monomer (M₃). The chemical structures of the monomers were characterized by Fourier transform infrared and ¹H‐nuclear magnetic resonance. The mesomorphic properties and phase behavior were investigated by differential scanning calorimetry, thermo gravimetric analysis, polarizing optical microscopy, and X‐ray diffraction. With an increase of europium complexes units in the polymers, the glass transition temperature (T_g) did not change significantly; the isotropic temperature (T_i) and mesophase temperature range (ΔT) decreased. All polymers showed typical cholesteric Grandjean textures, which was confirmed by X‐ray diffraction. The temperatures at which 5% weight loss occurred (T_d) were greater than 300°C for the polymers. The introduction of europium complexes units did not change the liquid crystalline state of polymer systems; on the contrary, the polymers were enabled with the significant luminescent properties. With Eu³⁺ ion contents ranging between 0 and 1.5 mol %, luminescent intensity of polymers gradually increased and luminescent lifetimes were longer than 0.45 ms for the polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40866.     

Crystal structure,curing kinetics,and thermal properties of bisphenol fluorene epoxy resin

Diglycidyl ether of 9,9‐bis(4‐hydroxyphenyl) fluorene (DGEBF) monomer was successfully synthesized and characterized in detail. The crystal structure of DGEBF was measured by single‐crystal X‐ray diffraction analysis. Curing kinetics of DGEBF with 4,4‐diaminodiphenyl sulfone (DDS), thermal properties, and decomposition kinetics were investigated using nonisothermal differential scanning calorimetry (DSC) according to Kissinger, Ozawa and Crane methods. The glass transition temperature (T_g), thermal properties of cured polymer were estimated by DSC, dynamic mechanical analysis, and thermogravimetric analyses. Epoxy value of DGEBF monomer up to theoretical value leads to higher crosslink density of cured polymers. The cured DGEBF/DDS system exhibited obvious higher T_g and better thermal stability compared to those of DGEBF/diamine systems reported previously. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Novel propargylether‐terminated monomers containing pyridine and phenyl pendent group: Synthesis,cure, and properties

Two novel propargylether‐terminated resins containing pyridine and bulky phenyl pendent group were prepared from propargyl bromide and different diphenols, and highly thermal stable polymers were obtained by the thermal cure of the monomers. The chemical structures of these novel monomers were well confirmed by FTIR, ¹H‐NMR and elemental analysis. Curing and thermal behavior of the resins were investigated using differential scanning calorimetry (DSC) and dynamic thermogravimetry in argon atmosphere. DSC curves of these two monomers showed a single endothermic peak corresponding to the conformation of chromene ring and homopolymerization of the chromene ring. The temperature at 5% weight loss (T_d5) was higher than 440°C under argon and the highest glass transition temperature (T_g) reached 362°C. The rheological behavior and solubility of the monomer were also investigated. The monomers showed excellent flow‐ability, broad processing window, and great solubility. These results showed that the two resins could be ideal candidates for high‐temperature resistant resins. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40469.     

Synthesis of a novel difunctional NLO azo‐dye chromophore and characterizations of crosslinkable copolymers with stable electrooptic properties

The synthesis and the nonlinear optical (NLO) properties of crosslinkable copolymers based on a novel NLO azo‐dye chromophore bearing two functions: one used the free‐radical copolymerization, that is, the methacrylate group, and the other one used for the crosslinking process, that is, the carboxylic acid function, are described. Copolymerization of this new monomer with glycidyl methacrylate leads to novel soluble crosslinkable NLO copolymers bearing free epoxy and carboxylic groups. The poling process, before crosslinking, is achieved at a temperature (T_p) close to the glass transition temperature, T_g (<70°C), of the copolymers. At this temperature, no reaction takes place between epoxy and carboxylic acid functions. In fact, crosslinking begins to start at a higher temperature, T_c (T_c ≫ T_p ≈ T_g). After the optimization of the poling and crosslinking processes, the NLO crosslinked polymer with 30 mol % of the chromophore exhibits a T_g of 157°C and a high quadratic susceptibility (d₃₃) of 30 pm/V at 1320 nm. This coefficient is stable at 85°C for several weeks. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 974–982, 1999     

Accelerated controlled radical polymerization of methacrylates

BACKGROUND: Nitroxide adducts 1,1‐ditertbutyl‐1‐(1‐methyl‐1‐cyanoethoxy)‐amine (AIBN/DBN), 1,1‐ditertbutyl‐1‐(benzoylperoxy)‐amine (BPO/DBN) and 2,2,6,6,‐tetramethyl‐4‐oxo‐1‐(1‐methyl‐1‐cyanoethoxy)‐piperidine (AIBN/4‐OXO‐TEMPO) were prepared and evaluated as stabilized unimolecular initiators for controlled radical polymerization of methacrylate monomers using sulfuric acid as an accelerating additive. Their effectiveness was evaluated from polymerization rates, molecular weight control and dispersity (D) of the polymers. Thermal stabilities of the polymers were also examined. The monomers used were methyl methacrylate, triethylene glycol dimethacrylate (TEGDMA) and ethoxylated bisphenol A dimethacrylate (EBPADMA). RESULTS: Polymerization was accomplished at 70 and 130 °C in 5 min to 144 h. The value of D of poly(methyl methacrylate) (PMMA) was 1.05–1.22. The glass transition temperature (T_g) for PMMA was 122–127 °C. The activity of the chain ends was established by chain extension and controlled polymerization was established by plotting M_n versus monomer conversion. First‐order kinetics in monomer consumption was established and an electron paramagnetic resonance study was conducted. Decomposition temperature (T_d) for PMMA was 360–380 °C, for poly(TEGDMA) was 300–380 °C and for poly(EBPADMA) was 360–440 °C. Photoinitiation without additive yielded no polymer. Thermal initiation by AIBN/4‐OXO‐TEMPO was the fastest. CONCLUSIONS: The initiators are applicable in low‐temperature additive‐enhanced controlled polymerization of methacylates and dimethacrylates, producing polymers with excellent attributes and a low value of D. Copyright © 2008 Society of Chemical Industry     

Synthesis and characterization of poly(urethane‐ester)s based on calcium salt of mono(hydroxybutyl)phthalate

Calcium‐containing poly(urethane‐ester)s (PUEs) were prepared by reacting diisocyanate (HMDI or TDI) with a mixture of calcium salt of mono(hydroxybutyl)phthalate [Ca(HBP)₂] and hydroxyl‐terminated poly(1,4‐butylene glutarate) [HTPBG₁₀₀₀], using di‐n‐butyltin‐dilaurate as catalyst. About six calcium‐containing PUEs having different composition were synthesized by taking the mole ratio of Ca(HBP)₂:HTPBG₁₀₀₀:diisocyanate (HMDI or TDI) as 3:1:4, 2:2:4, and 1:3:4. Two blank PUEs were synthesized by the reaction of HTPBG₁₀₀₀ with diisocyanate (HMDI or TDI). The polymers were characterized by IR, ¹H NMR, Solid state ¹³C‐CP‐MAS NMR, TGA, DSC, XRD, solubility, and viscosity studies. The T_g value of PUEs increases with increase in the calcium content and decreases with increase in soft segment content. The viscosity of the calcium‐containing PUEs increases with increase in the soft segment content and decreases with increase in the calcium content. X‐ray diffraction patterns of the polymers show that the HMDI‐based polymers are partially crystalline and TDI‐based polymers are amorphous in nature. The dynamic mechanical analysis of the calcium‐containing PUEs based on HMDI shows that with increase in the calcium content of polymer, modulus (g′ and g″) increases at any given temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1720–1727, 2006     

Effects of crosslinking degree and carbon nanotubes as filler on composites based on glycidyl azide polymer and propargyl‐terminated polyether for potential solid propellant application

Triazole crosslinked polymers were prepared by reacting glycidyl azide polymer (GAP) with the propargyl ‐ terminated poly(tetramethylene oxide) (PTMP) at different molar ratios of azide versus alkyne. Based on the optimum mechanical properties of the GAP/PTMP ‐ 2.5, a series of GAP/PTMP nanocomposites reinforced by either multi ‐ walled carbon nanotubes (MWCNTs) or carboxy ‐ functionalized multiwalled carbon nanotubes (MWCNTs ‐ COOH) were prepared with different mass ratios. The glass transition temperatures (T_{g, PTMP}) assigned to PTMP of the GAP/PTMP composites almost kept at a constant range when the molar ratio of azide versus alkyne was from 1.0 to 2.5. When the loading MWCNTs was 1.0 wt %, the tensile strength and elongation at break achieved a maximum of 1.77 MPa and 36.3%, respectively. The nanocomposites with nearly similar T_{g, PTMP} indicated no phase separation in the crosslinked polymers. The results revealed that the improved properties of GAP ‐ based materials could be achieved by changing the molar ratio of azide versus alkyne and the nanofillers content. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45359.     

Synthesis of soluble and thermally stable polyamides from diamine containing (quinolin‐8‐yloxy) aniline pendant group

A novel diamine monomer having pendant 4‐(quinolin‐8‐yloxy) aniline group was successfully synthesized via aromatic substitution reaction of 8‐quinolinol with p‐fluoronitrobenzene followed by Pd/C catalyzed hydrazine reduction, amidation reaction between 4‐(quinolin‐8‐yloxy) aniline and 3,5‐dinitrobenzoylcholoride followed by Pd/C catalyzed hydrazine reduction. The diamine monomer was fully characterized by using FTIR, ¹H‐NMR, ¹³C‐NMR, and elemental analysis. The diamine monomer was polymerized with various aromatic and aliphatic dicarboxylic acids to obtain the corresponding polyamides. The polyamides had inherent viscosity in the range of 0.30–0.41 dL/g and exhibited excellent solubility in the polar aprotic solvents such as DMAc, NMP, N,N‐dimethylformamide, Pyridine, and DMSO. The glass transition temperatures (T_g) of the polymers are high (up to 313°C) and the decomposition temperatures (T_i) range between 200 and 370°C, depending on the diacids residue in the polymers backbone. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and properties of ester or cyano group substituted ring-opening polymers and their hydrogenated derivatives

Ester or cyano substituted tetracyclo [4.4.0.1^2,5.1^7,10]dodec-3-enes (1) were synthesized and their metathesis ring-opening polymerization was examined. The tungsten-based ternary catalyst system polymerized them very well. The polymers showed high glass transition temperatures (T_g) and no evidence of crystallization (e.g., the T_g of the polymer derived from 8-methyl-8-methoxycarbonyl substituted monomer (1a) was 207°C, and colorless transparent films could be casted from the solution of the polymer). The stability of these high T_g polymers were too unstable, so practical thermal molding methods could not be applied to them. The hydrogenation of these polymers with a palladium catalyst decreased T_g and greatly increased thermal stability. The physical and thermal properties of the hydrogenated polymers were thoroughly investigated. Monomer 1 was successfully copolymerized with other cyclic olefins. The resultant copolymers were hydrogenated, giving thermally stable polymers. In all cases examined in this study, a decrease of T_g by hydrogenation was about 35°C, regardless of the monomer structure. These results indicate that the main-chain mobility is the major contribution to the decrease of T_g. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 367–375, 1997     

Flexible all‐aromatic polyesterimide films with high glass transition temperatures

A series all‐aromatic poly(esterimide)s with different molar ratios of N‐(3′‐hydroxyphenyl)‐trimellitimide (IM) and 4‐hydroxybenzoic acid (HBA) (IM/HBA = 0.3/0.7 and 0.7/0.3) was prepared with the aim to design flexible high T_g films. Melt‐pressed films, either from high molecular weight polymer or cured phenylethynyl precursor oligomers, exhibit T_gs in the range of 200 °C to 242 °C and are brittle. After a thermal stretching procedure, the films became remarkably flexible and very easy to handle. In addition, the thermally stretched 3‐IM/7‐HBA and 7‐IM/3‐HBA films show tensile strengths of 108 MPa and 169 MPa, respectively. Thermal treatment increased the T_g of 3‐IM/7‐HBA from 205 °C to 248 °C, whereas the T_g of 7‐IM/3‐HBA increased from 230 °C to 260 °C. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 133, 44774.     

Synthesis and characterization of novel polyimides starting from 1,2‐bis(p‐dimethylaminobenzylideneimino)alkane homologues and various dianhydrides

The objective of this research was the preparation of polyimides from 1,2‐bis(p‐dimethylaminophenylimino)alkane homologues and various dianhydrides in N‐methylpyrrolidone by one‐stage polycondensation. The monomers were prepared via condensation of p‐dimethylaminobenzaldehyde and the corresponding diamines, 1,4‐diaminobutane, 1,3‐diaminopropane and 1,2‐diaminoethane. The influence of the incorporation of this moiety into the polymer backbone on the properties of the polyimides has been evaluated. The thermogram of the polyimides indicated that PI‐10 to PI‐32 had T_g values ranging from 181 to 290 °C. The inherent viscosities of the polymers ranged from 0.99 to 2.05 dl g^?1, and the highest solubility was obtained without significant loss of the thermal properties. Copyright © 2004 Society of Chemical Industry     

A comparison of triazole cross‐linked polymers based on poly‐AMMO and GAP: Mechanical properties and curing kinetics

Triazole cross‐linked polymers based on poly(3‐azidomethyl‐3‐methyl oxetane) (poly‐AMMO) and glycidyl azide polymer (GAP) were prepared using bis‐propargyl‐1,4‐cyclohexyl‐dicarboxylate (BPHA) as curing agent, respectively. Swelling tests demonstrated that cross‐linking densities of the resulted polymers both increased with the increase of BPHA. Triazole cross‐linked polymers based on poly‐AMMO showed superior tensile strength and elongation at break than those of GAP at comparable stoichiometry. The curing kinetics was also investigated by FTIR, and GAP exhibited faster reaction rate when reacted with BPHA than that of poly‐AMMO. In addition, with the increase of cross‐linking density, the glass transition temperature (T_g) of as‐prepared polymers significantly increased, and poly‐AMMO‐based polymers showed stronger T_g‐raising effect than GAP‐based polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43341.     

Synthesis of branched benzoxazine monomers with high molecular mass,wide processing window,and properties of corresponding polybenzoxazines

Four cyclotriphosphazene‐based benzoxazine monomers (I, II, III, and IV) with relatively high molecular weight were synthesized by a nucleophilic substitution reaction, and their chemical structures were confirmed by ¹H‐NMR and ³¹P‐NMR. A new term, oxazine value (OV, similar to epoxy value), was first proposed to explain the structure–property relationship of the cured polymers. The polymerization behaviors of the four monomers were studied by differential scanning calorimetry and Fourier transform infrared spectroscopy. The maximum exothermic peaks of the four monomers are in the range 244–248 °C. All monomers possess a wide processing window despite their high molecular weight. The thermal stability, glass‐transition temperature (T_g), and mechanical properties of each cured polymer were studied by thermogravimetric analysis and dynamic mechanical thermal analysis. The char yield at 850 °C, T_g, and storage moduli of PIV (polybenzoxazine obtained from monomer IV) are 60.0%, 218 °C, and 9.0 GPa, respectively. The surface property and humidity absorption character of the cured polybenzoxazines were also studied. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44453.     

The glass‐forming ability and thermal stability of novolac–phenolic resin

Glass‐forming ability and thermal stability of novolac–phenolic resin with different contents of curing agent hexamethylenetramine (HMTA) are investigated. Melt fragility (M_g) and T_gd (T_gd = T_g/T_d) are proposed to characterize glass‐forming ability and thermal stability of the novolac–phenolic resin, respectively. It is found that M_g has a negative linear relationship with T_gd. The lower M_g represents the better glass‐forming ability of liquid phenolic resin while the higher T_gd represents the better thermal stability of the fully cured phenolic resin. Further more, M_g establishes a kinetic relationship between glass‐forming ability of liquid uncured and thermal stability of fully cured novolac–phenolic resin in terms of comparing with T_gd. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Synthesis and characterization of network liquid crystal elastomers and thermosets

A new series of network liquid crystal polymers were synthesized by graft copolymerization of the difunctional mesogenic monomer 4‐allyloxy‐benzoyloxy‐4′‐allyloxybiphenyl (M) upon polymethylhydrosiloxane (PMHS). Monomer M acted not only as a mesogenic unit but also as a crosslinker for the network polymers. The chemical structures of the polymers were confirmed by IR spectroscopy. DSC, TGA, and X‐ray scattering were used to measure their thermal properties and mesogenic properties. The glass transition temperature (T_g) of these network liquid crystal polymers was increased when the monomer was increased, and T_d (temperature of 5% weight loss) at first went up and reached a maximum at P₁, then went down. The slightly crosslinked polymers (P₀, P₁) show rubber‐like elasticity, so it was called liquid‐crystal elastomer. Network polymers will lose elasticity property with a highly crosslinked degree, and turn into thermosetting polymers (P₄, P₅). All polymers exhibited a smectic texture by X‐ray scattering. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1104–1109, 2002     

Low relative dielectric permittivities of polyimides and copolyimides derived from non-coplanar diamines and 4,4′-(hexafluoroisopropyl)diphthalic anhydride

Abstract

Two series of polyimides and copolyimdes were solution cast into transparent, flexible and tough films. The glass transition temperatures T _g obtained from dynamic mechanical analysis were moderate compared with commercial polyimides such as Dupont Vespel®. The T _gs for the majority of polymers derived from monomer 1 (2′,5′-bis(p-aminophenoxy)-[1,1′;4′,1≥]terphenyl) (1A-F) were higher than those of polymers derived from monomer 2 (2,5-bis(p-aminophenoxy)biphenyl) (2A-F). The thermal expansion coefficients of the two series of polymers were moderate and comparable. The maximum elongations and moduli of polymers 2A-F were larger than those of polymers 1A-F possibly because polymers 2A-F were more flexible than polymers 1A-F. The relative dielectric permittivities of both series of polymers were measured and exhibited a low value from 2 49 to 3 01 at 100 kHz. In contrast, the relative permittivities calculated using the Clausius-Mosotti relationship were higher. Incorporation of non-coplanar diamines into the polymer chain causes an increase in free volume, which may account for the decrease in relative permittivities.     

Design of polymers for migration imaging application II: Synthesis and polymerisation of p-isobutyl styrene

A copolymer series was synthesized for migration imaging applications from isobutyl methacrylate and isobutyl styrene such that each homopolymer and all copolymers had glass transition temperature (T_g) near 55°C. The T_g of poly (p-isobutylstyrene) was predicted from literature values of similar polymers to be near 55°C. Poly (p-isobutylstyrene) was synthesised by acetylation of isobutyl benzene, reduction of p-isobutylacetoph-enone to the carbinol, dehydration to p-isobutylstyrene and free radical polymerisation to the polymer. The T_g of the homopolymer was 55°C, in excellent agreement with the predicted value. Copolymers of isobutyl methacrylate and p-isobutyl styrene were synthesised and their T_g's measured across the series by DSC (57°C ± 5°C). refractive index temperature coefficient (42°C ± 5°C). The copolymer series was also characterised by melt viscosity measurements.     

Transport parameters and solubility coefficients of polymers at their glass transition temperatures

Many parameters of polymers exhibit breaks when temperature passes through glass transition. It is also often assumed that fractional free volume (FFV) at the glass transition temperature (T_g) has a standard value (the isofree volume concept). As gas diffusion (D) and permeability (P) coefficients depend on FFV, and mechanism of sorption and permeation is different above and below T_g, a question can be asked if D and P parameters of various gases in polymers have standard values at corresponding T_g, and, if not, how the values of D(T_g) and P(T_g) vary with T_g in different polymers. To examine this problem, two approaches were used: (1) extrapolation to T_g of numerous P and D values measured at ambient temperatures; (2) an analysis of direct data obtained in different polymers at their T_g. In both cases, qualitatively similar results were obtained: the D(T_g) and P(T_g) values increase with growing T_g independently of the nature of gas. Permselectivity P_i(T_g)/P_j(T_g) and selectivity of diffusion D_i(T_g)/D_j(T_g) are reduced when T_g increases. The dependence of the solubility coefficients S(T_g) = D(T_g)/P(T_g) is much weaker than those of D(T_g) and P(T_g). This conclusion was confirmed by the results of direct measurements of S in a wide range of temperature including T_g for several gas/polymer systems. An analysis of the results of positron annihilation studies of free volume in polymers led to the conclusion that the observed increases in the D(T_g) and P(T_g) values with T_g are caused mainly by thermal activation of diffusion processes at T_g. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1691–1705, 2000