High optical transparency, low dielectric constant and light color of novel organosoluble polyamides with bulky alicyclic pendent group

Novel optically transparent, low dielectric and highly organosoluble alicyclic polyamides derived from bulky alicyclic diamine containing trifluoromethyl group on either side, 1,1-bis[4-(2-trifluoromethyl-4-aminophenoxy)phenyl]-4-tert-butylcyclohexane (BTFAPBC), were prepared. The polyamides were obtained in almost quantitative yields and showed inherent viscosity values between 0.55 and 0.72 dL g⁻¹ in DMAc solution. Most of the polyamides showed excellent solubility in polar solvents such as N-methyl-2-pyrrolidinone (NMP), N,N′-dimethyl acetamide (DMAc), N,N′-dimethyl formamide (DMF), pyridine, cyclohexanone, γ-butyrolactone and chloroform. The cut-off wavelength for polyamides ranged from 350 to 388 nm. Polyamides with alicyclic tert-butylcyclohexyl cardo and trifluoromethyl substituents exhibited low dielectric constants ranging from 3.29 to 3.98 (at 100 Hz) compared with commercially available polyamides [Amodel^®, 4.2-5.7 at 100 Hz]. Polyamides showed glass transition temperatures in the range of 244-266 °C and possessed a coefficient of thermal expansion (CTE) of 60-75 ppm °C⁻¹. Thermogravimetric analysis data showed that the polyamides were stable up to 430 °C and the 10% weight loss temperature was found to be in the range of 437-466 °C in nitrogen atmosphere. The polyamide films had a tensile strength in the range of 66-103 MPa, elongation at break in the range of 5-8%, and tensile modulus in the range of 1.5-2.2 GPa. Due to their properties, the polyamides could be considered as engineering plastic and photoelectric materials.     

Synthesis and characterization of novel fluorinated polyimides derived from 4,4′-[2,2,2-trifluoro-1-(3,5-ditrifluoromethylphenyl)ethylidene]diphthalic anhydride and aromatic diamines

A novel fluorinated aromatic dianhydride, 4,4′-[2,2,2-trifluoro-1-(3,5-ditrifluoromethylphenyl) ethylidene] diphthalic anhydride (9FDA), was synthesized, which was employed to polycondense with various aromatic diamines, including 4,4′-oxydianiline, 1,4-bis(4-aminophenoxy) benzene, 3,4′-oxydianiline and 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene to produce a series of fluorinated aromatic polyimides. The fluorinated polyimides obtained had inherent viscosities ranged of 0.61-1.14 dL/g and were easily dissolved both in polar aprotic solvents and in low boiling point common solvents. High quality polyimide films could be prepared by casting the polyimide solution on glass plate followed by thermal baking to remove the organic solvents and volatile completely. Experimental results indicated that the fluorinated polyimides exhibited good thermal stability with glass transition temperature ranged of 245-283 °C and temperature at 5% weight loss of 536-546 °C. Moreover, the polyimide films showed outstanding mechanical properties with the tensile strengths of 87.7-102.7 MPa and elongation at breaks of 5.0-7.8%, good dielectric properties with low dielectric constants of 2.71-2.97 and low dissipation factor in the range of 0.0013-0.0028.     

Synthesis and characterization of novel polyimides derived from 2-amino-5-[4-(4′-aminophenoxy)phenyl]-thiazole with some of dianhydride monomers

A new kind of aromatic unsymmetrical diamine monomer containing thiazole ring, 2-amino-5-[4-(4′-aminophenoxy)phenyl]-thiazole (APPT), was synthesized. A series of novel polyimides were prepared by polycondensation of APPT with various aromatic dianhydrides via one-step process. The resulting polyimides held inherent viscosities of 0.40-0.71 dL/g and were easily dissolved in strong dipolar solvents. Meanwhile, strong and flexible polyimide films were obtained, which had thermal stability with the glass transition temperatures (T_g) of 268.2-328.8 °C in nitrogen, the temperature at 5% weight loss of 452-507 °C in nitrogen and 422-458 °C in air, and the residue at 800 °C of 54.18-63.33% in nitrogen, as well as exhibited outstanding mechanical properties with the tensile strengths of 105.4-125.3 MPa, elongations at breakage of 6-13%. These films also held dielectric constants of 3.01-3.18 (10 MHz) and showed predominantly amorphous revealed by wide-angle X-ray diffraction measurements.     

Synthesis and characterization of adamantane-containing poly(enaminonitriles)

The first aliphatic bis(chlorovinylidene cyanide) monomer, 1,3-bis(1-chloro-2,2-dicyanovinyl)adamantane, has been synthesized and polymerized with appropriate diamines to give adamantane-containing aromatic-aliphatic and all aliphatic poly(enaminonitriles) (PEANs) via vinylic nucleophilic substitution polymerization. The PEANs showed excellent solubility in polar aprotic solvents and good thermal stability (10% weight loss in air > 320 °C), despite the aliphatic contents of the polymers. Solution inherent viscosities of 0.23-0.90 dL/g were obtained.Three other new PEANs containing the adamantane-based cardo group were also synthesized via vinylic nucleophilic substitution polymerization from the adamanaine-containing cardo diamine 2,2-bis[4-(4-aminophenoxy)phenyl]adamantane. The cardo PEANs showed better solubility in common organic solvents than the corresponding cardo polyamides. They also showed good thermal stabilities (10% weight loss in air > 339 °C) comparable to those of the corresponding cardo polyamides.     

Color lightness and highly organosoluble fluorinated polyamides, polyimides and poly(amide-imide)s based on noncoplanar 2,2′-dimethyl-4,4′-biphenylene units

A new diamine monomer containing noncoplanar methyl substitution, 2,2′-dimethyl-4,4′-bis(2-trifluoromethyl-4-aminophenoxy)biphenyl (DBTFAPB) was successfully synthesized and used in the preparation of a series of polyamides and polyimides by direct polycondensation with various aromatic dicarboxylic acids and tertacarboxylic dianhydrides. A new noncoplanar dicarboxylic acid monomer containing noncoplanar methyl substitution, 2,2′-dimethyl-4,4′-bis(2-trifluoromethyl-4-trimellitimidophenoxy)biphenyl (DBTFTPB) was also successfully synthesized by refluxing the diamine, DBTFAPB, with trimellitic anhydride in glacial acetic acid. A series of new poly(amide-imide)s were prepared directly from DBTFTPB with various diamines in N-methyl-2-pyrrolidinone (NMP). All the polymers exhibited excellent solubility in solvents, such as N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridine, tetrahydrofuran (THF), cyclohexanone and γ-butyrolactone at room temperature or upon heating at 70 °C. Inherent viscosities of the polymers were found to range between 0.60 and 1.34 dL g⁻¹. Gel permeation chromatography (GPC) of the polymers showed number-average and weight-average molecular weight up to 7.3×10⁴ and 17.9×10⁴, respectively. These polymers showed that the glass transition temperatures were between 230 and 265 °C, and the 10% mass loss temperatures were higher than 460 °C in nitrogen atmosphere. All the polymers could be cast into flexible and tough films from DMAc solutions. They had a tensile strength in the range of 82-124 MPa and a tensile modulus in the range of 1.9-2.9 GPa. These polymers exhibited low dielectric constants ranging from 2.87 to 4.03, low moisture absorption in the range of 0.29-3.20%, and high transparency with an ultraviolet-visible absorption cut-off wavelength in the 347-414 nm range.     

New soluble triphenylamine-based amorphous aromatic polyamides for high performance blue-emitting hole-transporting and anodically electrochromic materials

A newly 4-methoxy-substituted triphenylamine-containing aromatic diacid monomer, 4,4′-dicarboxy-4″-methoxytriphenylamine 2, with blue light (454 nm) fluorescence quantum efficiency 45% was successfully synthesized by the sodium hydride-mediated condensation of 4-methoxyaniline with 4-fluorobenzonitrile, followed by alkaline hydrolysis of the intermediate dicyano compound. A series of novel aromatic polyamides having strong fluorescence emissions in the blue region with high quantum yields up to 40% and one reversible oxidation redox couples at 1.08 V vs. Ag/AgCl in acetonitrile solution have been synthesized and characterized. They exhibited good thermal stability with 10% weight-loss temperatures above 460 °C under a nitrogen atmosphere with relatively high glass-transition temperatures (267-307 °C). All obtained polyamides revealed excellent stability of electrochromic characteristics, changing color from original pale yellowish to blue.     

Synthesis and characterization of novel polyimides derived from 1,1-bis[4-(4′-aminophenoxy)phenyl]-1- [3″,5″-bis(trifluoromethyl)phenyl]-2,2,2-trifluoroethane

A novel fluorinated aromatic diamine monomer, 1,1-bis[4-(4′-aminophenoxy)phenyl]-1-[3″,5″-bis(trifluoromethyl)phenyl]-2,2,2-trifluoroethane(9FTPBA), was synthesized by coupling 3′,5′-bis(trifluoromethyl)-2,2,2-trifluoroacetophenone with 4-nitrophenyl phenyl ether under the catalysis of trifluoromethanesulfonic acid, followed reduced by reductive iron and hydrochloric acid. A series of new fluorine-containing polyimides having inherent viscosities of 0.96-1.23 dl/g was synthesized from the novel diamine with various commercially available aromatic dianhydrides using a standard two-stage process with thermal imidization and chemical imidization of poly(amic acid) films. All the fluorinated polyimides were soluble in many polar organic solvents such as NMP, DMAc, DMF, and m-cresol, as well as some of low boiling point organic solvents such as chloroform and acetone. The polymer films have good thermal stability with the glass transition temperature of 223-225 °C, the temperature at 5% weight loss of 535-568 °C in nitrogen, and have outstanding mechanical properties with the tensile strengths of 68-89 MPa, initial moduli of 2.14-2.19 GPa, and elongations at breakage of 3.2-10.5%.     

Synthesis and properties of novel sulfonated polyimides bearing sulfophenyl pendant groups for fuel cell application

A novel sulfonated diamine bearing sulfophenyl pendant groups, namely, 4,4′-bis (4-aminophenoxy)-3,3′-bis(4-sulfophenyl) biphenyl and a series of sulfonated polyimides (SPIs) based on it were successfully synthesized. The SPIs had high viscosity and gave tough, flexible and transparent membranes. The SPI membranes showed anisotropic membrane swelling in water with 2.5-4 times larger swelling in thickness direction than in plane one. They displayed reasonably high proton conductivity. For example, the conductivities for the SPI with an ion exchange capacity of 1.80 mequiv/g were 104 and 7.3 mS/cm in water and 50% RH, respectively, at 60 °C. They maintained high mechanical strength and proton conductivity even after aging in water at 130 °C for 500 h, showing the high water stability comparable to the best SPI reported so far. In polymer electrolyte fuel cells (PEFCs) operated at 90 °C and 50% RH, they showed fairly high cell performances and have high potential for PEFC applications.     

Synthesis and properties of novel side-chain-sulfonated polyimides from bis[4-(4-aminophenoxy)-2-(3-sulfobenzoyl)]phenyl sulfone

A novel side-chain-sulfonated aromatic diamine of bis[4-(4-aminophenoxy)-2-(3-sulfobenzoyl)]phenyl sulfone (BAPSBPS) was synthesized. Sulfonated copolyimides were synthesized by random and sequenced block copolymerization of 1,4,5,8-naphthalene tetracarboxylic dianhydride, BAPSBPS and nonsulfonated diamine. They displayed good solubility in common aprotic solvents and high desulfonation temperature of 350 °C, suggesting the high stability of sulfonic acid groups. The reduced viscosity was in the range of 0.4-1.8 dl/g at 0.5 g/dl and 35 °C. Flexible and tough membranes with reasonably high mechanical strength were prepared. They showed anisotropic membrane swelling with larger swelling in thickness than in plane. They displayed reasonably high proton conductivity (σ), taking their lower ion exchanging capacity (IEC) into account. For example, the membrane with IEC of 1.54 mequiv/g showed σ values of 81 and 11 mS/cm in water and 70% RH, respectively, at 60 °C.     

Soluble and curable poly(phthalazinone ether amide)s with terminal cyano groups and their crosslinking to heat resistant resin

Soluble and curable aromatic polyamides have great potential use as processable and heat-resistant polymeric materials. In this study, a novel series of soluble aromatic polyamides (CN-PPAs) containing phthalazinone moiety and crosslinkable terminal cyano groups were synthesized by polycondensation of 1,2-dihydro-2-(4-carboxyphenyl)-4-[4-(4-carboxyphenoxyl)phenyl]-phthalazinone (DHPZ-DC) with calculated 4,4′-oxydianiline (ODA), followed by end-capping with 4-cyanobenzoic acid (CBA). Thermal crosslinking of CN-PPAs, catalyzed by zinc chloride, was then performed in the presence of terephthalonitrile (TPH) via heating either their films or powders up to 300-340 °C. The uncured synthesized polymers have good solubility while the cured samples become insoluble in common organic solvents. Spectra and elemental analysis measurements demonstrate cyclization reaction of terminal cyano groups to form s-triazine rings. The presence of TPH and ZnCl₂ is effective in promoting thermal crosslinking and s-triazine forming reaction of the CN-PPAs under normal pressure. The resulting cured samples exhibit no T_g up to 400 °C by DSC and have excellent thermal stability. This kind of cyano-terminated poly(phthalazinone ether amide) may be a good candidate as matrix for high performance polymeric materials.     

Synthesis and characterization of novel soluble fluorinated aromatic polyamides derived from fluorinated isophthaloyl dichlorides and aromatic diamines

Two series of fluorinated aromatic polyamides derived from two novel monomers, 5-(4-trifluoromethylphenoxy)isophthaloyl dichloride (3FPC) and 5-(3,5-bistrifluoromethyl-phenoxy)isophthaloyl dichloride (6FPC) with various aromatic diamines were synthesized and characterized. Experimental results indicated that the fluorinated aromatic polyamides showed good solubility in many organic solvents. The solubility of the polyamides was affected by the trifluoromethyl substituents and the pendent phenoxy groups in the polymer backbone. The fluorinated polyamides have good thermal stability with the glass transition temperature of 206-285 °C, the temperature at 5% weight loss of 442-460 °C in nitrogen. The polyamide films also exhibited good mechanical properties and excellent electrical and dielectric properties. The fluorinated groups in the polymer backbone have played an important role in the improvement of electrical and dielectric performance of polymer.     

Synthesis and properties of organosoluble polyimides based on 1,1-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]cyclohexane

New aromatic diamine with cyclohexane cardo group substituted with trifluoromethyl group in the side chain, 1,1-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]cyclohexane (II), was prepared through the nucleophilic substitution reaction of 1,1-bis(4-hydroxyphenyl)cyclohexane and 2-chloro-5-nitrobenzotrifluoride in the presence of potassium carbonate, to yield the intermediate dinitro compound I, followed by catalytic reduction with hydrazine and Pd/C to afford the diamine II. Fluorinated polyimides (IVa-g) were prepared from the II with various aromatic dianhydrides via thermal or chemical imidization of poly(amic acid). These polyimides had inherent viscosity ranging from 0.72 to 1.16 dl/g and showed excellent solubility in a variety of organic solvents. They were soluble in a concentration of 10% in the amide polar solvent, and 1-5% in the other testing solvents. IV films showed good mechanical properties, excellent thermal stability. The 10% weight loss temperature was above 476 °C in nitrogen or air, and the glass transition temperature was recorded at 214-278 °C. In comparison of the IV series with the analogous nonfluorinated polyimides (V series) based on 1,1-bis[4-(4-aminophenoxy)phenyl]cyclohexane (II′), IV series revealed better solubility, lighter-colored and lower dielectric constants and moisture absorptions. Their films had cut-off wavelengths in the range of 364-414 nm, b^* value (a yellowness index) ranging from 3.3 to 66.3, dielectric constants of 3.02-3.55 (1 MHz), with moisture absorption of 0.16-0.36 wt%.     

Synthesis and properties of aliphatic spirodilactam diphenol containing polyesters

A series of aromatic polyesters containing 1,6-diazaspiro[4,4]-nonane-2,7-dione were synthesized under phase-transfer conditions. The copolymers were obtained in essentially quantitative yield, theses were soluble in common organic solvents, and would readily form clear, colorless films from solution. The optimum conditions of polymerization, was obtained via polycondensation at room temperature and reaction time of 4 h in chloroform. All polymers were characterized by FTIR, GPC, viscosity, water contact angle, water absorption, TGA, DSC and TMA. The prepared polyesters showed excellent thermal stability, as measured by TGA (10 wt% loss), are only moderate due to the alicyclic component and range from 365 to 401 °C in air; however, glass transition temperatures are quite high (245-309 °C). The inherent viscosities of these solutions ranged from 0.77 to 1.40 dl g⁻¹, depending on the polyester structure. The structures of the polyesters were confirmed by FTIR spectroscopy.     

Synthesis,characterization, and properties of novel aromatic polyamides containing phthalazinone moiety

A unsymmetrical and kink non-coplanar heterocyclic dicarboxylic acid monomer, 4-[4-(4-carboxy phenoxy)-naphthyl]-2-(4-carboxyphenyl)phthalazin-1-one (3) was successfully synthesized with high purity and high yields. A series of novel polyamides containing phthalazinone were prepared from the newly synthesized dicarboxylic acid with various aromatic diamines by means of the phosphorylation polycondensation reaction. Molecular weights of the obtained polyamides were evaluated viscometrically, and the inherent viscosities (η_inh) measured were in the range 0.54–0.69 dL/g. These polyamides were amorphous and readily soluble in many organic solvents, such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimetheylformamide, dimethyl sulfoxide, pyridine, and m-cresol etc., and they could easily be solution-cast into transparent, flexible films with good mechanical properties, with tensile strength ranging from 63.9 to 81.6 MPa and elongation at break from 7.2 to 11.4%. These polymers still kept good thermal stability with high-glass transition temperatures in the range of 283–338 °C, and the decomposition temperature in nitrogen for a 10% weight-loss temperatures in excess of 490 °C, and char yield at 800 °C in nitrogen ranged from 56 to 63%. Furthermore, the polyamides films were essentially colorless; their cut-off wavelengths were between 365 and 379 nm.     

Simultaneous growth of diamond thin films and carbon nanotubes at temperatures ?550 °C

Diamond thin films (on silicon wafers) and carbon nanotubes (CNTs) (on Inconel plates) were simultaneously synthesized at temperatures ?550 °C without any additional catalyst. The synthesis was achieved in a microwave plasma enhanced chemical vapor deposition (CVD) reactor with graphite etching in a gas mixture of hydrogen and methane. The substrate stage consisted of an Inconel 600 plate and a stainless steel plate separated by a 53 mm long quartz tube. Silicon wafers were placed on the stainless steel plate located at the upper part of the substrate stage, while Inconel plates were placed at the lower part of the substrate stage. During the deposition, the substrates were heated only by the plasma and the substrate temperature was controlled by the applied microwave power, which ranged from 350 W to 950 W. The backside temperatures of Si wafers ranged from 290 °C to 550 °C, higher than the corresponding temperatures of Inconel 600, which ranged from 220 °C to 350 °C. The Raman spectroscopic and electron microscopic results show that the thin films deposited on Si consist of well faceted polycrystalline diamond, and that the black soot deposited on Inconel plates is composed of multiwall carbon nanotubes as long as one millimeter.     

Synthesis and properties of soluble fluorinated poly(ether imide)s with different pendant groups

Two types of new fluorinated diamine monomer, [1,4-(4-amino-2-trifluoromethyl-phenoxy)-2-(3′-trifluoromethylphenyl) benzene (III)] and [1,4-(4-amino-2-trifluoromethyl-phenoxy)-2-(3′-methylphenyl) benzene (IV)] were synthesized and polymerized with aromatic dianhydrides. A series of soluble poly(ether imide)s (PEIs) were prepared from the diamines and dianhydrides by two-step chemical imidization methods. Experimental results indicated that all the PEIs had glass transition temperature between 230 °C and 247 °C, the temperature at 5% weight loss between 527 °C and 598 °C under nitrogen. The membranes hand tensile strengths in the range of 74-101 MPa, tensile modulus in the range of 1.9-2.6 GPa, and elongation at break from 20 to 28%. The cast membranes also exhibited high optical transparency, with a UV-vis absorption edge of 354-406 nm. Moreover, these PEIs membranes possessed low dielectric constants of 2.63-3.20 (at 1 MHz) and low water uptakes (<0.75 wt%).     

Synthesis, characterization and optical properties of fluorinated poly(aryl ether)s containing phthalazinone moieties

A series of novel fluorinated poly(aryl ether)s containing phthalazinone moieties (FPPEs) have been prepared by a modified synthetic procedure for optical waveguide applications. The obtained random copolymers exhibited excellent solubility in polar organic solvents, high glass transition temperatures (T_gs: 185-269 °C), good thermal stabilities (the temperatures of 1% weight loss: 487-510 °C) and good optical properties. By adjusting the feed ratio of the reactants, the refractive indices of TE and TM modes (at 1550 nm) could be well controlled in the range of 1.575-1.498 and 1.552-1.484, respectively. The optical losses of the FPPEs exhibited relatively low values (less than 0.27 dB/cm at 1310 nm). Additionally, the thermo-optic coefficient (dn/dT) values of the FPPEs at 1310 nm and 1550 nm (TE mode) ranged from −0.97 × 10⁻⁴ °C to −1.33 × 10⁻⁴ °C and from −0.96 × 10⁻⁴ °C to −1.29 × 10⁻⁴ °C, respectively.     

Study of the incorporation of protic ionic liquids into hydrophilic and hydrophobic rigid-rod elastomeric polymers

A series of polymers was synthesized that contain a rigid aromatic backbone connected through triazine linkages that are cross-linked by flexible diamine-terminated poly(ethylene oxide) oligomers. Polymers were made that contained both hydrophilic sulfonated aromatic and hydrophobic pyridinium triflate backbones. Thermal and mechanical properties of the resulting polymer films were studied, as well as uptake of water and protic ionic liquids. Ionic liquid uptake varied from 41 to 440%, depending upon the nature of the polymer. The ionic liquid-doped films were analyzed for proton conductivity at high temperatures (>150 °C) under non-humidified conditions. Conductivities as high as 5×10⁻² S/cm were observed at 150 °C.     

Synthesis and characterization of partly fluorinated poly(phthalazinone ether)s crosslinked by allyl group for passive optical waveguides

It is necessary to introduce cross-linkable groups onto polymer chains as the processability and thermal stability of the polymers for passive waveguide device applications are very dependent on their cross-linking capabilities. Herein a series of novel cross-linkable allyl-containing fluorinated poly(phthalazinone ether)s (Allyl-FPPEs) have been prepared by a modified polycondensation of 4-(4-hydroxylphenyl)(2H)-phthalazin-1-one (DHPZ), decafluorobiphenyl (DFBP), 4,4′-(hexafluoroisopropylidene)diphenol (6F-BPA), and 3,3′-diallyl-4,4′-dihydroxybiphenyl (DA-DHBP) for optical waveguide applications. The obtained random polymers were characterized by FT-IR, NMR and GPC. The resulting polymers having good solubility in polar organic solvents at room temperature, can be easily spin-coated into thin films with attracting optical quality, good thermal stabilities (the temperatures of 1% mass-loss after curing: 455-503 °C), and high glass transition temperatures (T_gs: 167-251 °C) which could further increase by about 20 °C after thermal cross-linking. The crosslinked polymer films exhibit good optical properties. By adjusting the feed ratio of the reactants, the refractive indices of TE and TM modes (at 1550 nm) could be well controlled in the range of 1.4998-1.5618 and 1.4954-1.5520, respectively. The optical losses of the crosslinked polymers possess rather low values, less than 0.3 dB/cm at 1550 nm.     

Properties of films and fibers obtained from Lewis acid-base complexed nylon 6,6

A nylon 6,6 complex with GaCl₃ in nitromethane (4-5 wt% nylon 6,6) was prepared at 50-70 °C over 24 h for the purpose of disrupting the interchain hydrogen bonding between nylon 6,6 chains, resulting in amorphous nylon 6,6, and increasing the draw ratio for improving the performance of nylon 6,6 fibers. After drawing, complexed films and fibers were soaked in water to remove GaCl₃ and regenerate pure nylon 6,6 films and fibers. FTIR, SEM, DSC, TGA, and mechanical properties were used for characterization of the regenerated nylon 6,6 films and fibers. The amorphous complexed nylon 6,6 can be stretched to high draw ratios at low strain rates, due to the absence of hydrogen bonding and crystallinity in these complexed samples. Draw ratios of 7-13 can be achieved for complexed fibers, under low strain rate stretching. This study indicates that nylon 6,6 fibers made from the GaCl₃ complexed state, using a high molecular weight polymer, can reach initial moduli up to 13 GPa, compared to initial moduli of 6 GPa for commercial nylon 6,6 fibers. Lewis acid-base complexation of polyamides provides a way to temporarily suppress hydrogen bonding, potentially increasing orientation while drawing, and following regeneration of hydrogen bonding in the drawn state, to impart higher performance to their fibers.