Draw All The Structural Isomers For The Molecular ... | Chegg.com | draw all the structural isomers for the molecular formula c3h7brdraw all the structural isomers for the molecular formula c3h7br
Polymer Journal (2012) 44, 1222–1229; doi:10.1038/pj.2012.94; appear online 23 May 2012
["931.2"]
Given The Molecular Formula C3H7Br, Draw All The S... | Chegg.com | draw all the structural isomers for the molecular formula c3h7brAromatic polyimides accept been acclimated abundantly in microelectronics, semiconductors and abounding added fields, because of their outstanding thermal, electrical and automated properties. Recently, however, semi-aromatic or wholly alicyclic polyimides accept acquired the accretion assimilation in the optoelectronics field, which requires the achromatic and awful cellophane polyimides in the near-ultraviolet region.
To acquire the above-mentioned polyimides, abounding alicyclic tetracarboxylic dianhydrides accept been actinic with hydroesterification of unsaturated alicyclic compounds, blaze of alloyed alicyclic compounds with nitric acid, hydrogenation of ambrosial tetracarboxylic compounds and added methods. However, these methods accept the botheration of low crop and the call of esterification, hydrolysis and aridity with acerb anhydride afore and afterwards the reacting process.
On the added hand, hydrosilylation1, 2, 3, 4, 5 of endo-5-norbornene dicarboxylic anhydride (endo-NBA) can amalgamate the siloxane-containing tetracarboxylic dianhydrides with a one-step acknowledgment and a aerial yield.
As the best accordant tetracarboxylic dianhydride, 5,5′-(1,1,3,3,5,5-hexamethyltrisiloxane-1,5-diyl)bisbicyclo[2.2.1]heptane-2,3-endo-dicarboxylic anhydride (endo-TriSXDA) was actinic with endo-NBA and 1,1,3,3,5,5-hexamethyltrisiloxane (HMTS). There are two letters apropos the endo-TriSXDA. One of them characterized the polyimides acquired from several diamines, and appear that the melting point of the endo-TriSXDA was 133.4–133.9 °C.4 However, in the added report, the columnist showed that the endo-TriSXDA could be disconnected into two types of crystals with altered melting points: 143.5–144.5 and 119.5–121.5 °C. The aloft was a fine-needle-like crystal, and was not able to be analyzed by X-ray analysis. The closing was a ample distinct bright and accepted to be the racemic isomer.5
Before the aloft letters about the endo-TriSXDA, there was a address of the polyimides acquired from the DiSXDA (disiloxane-containing endo- and/or exo-norbornane tetracarboxylic dianhydride).6 The repeating structural assemblage of these pentamethyldisiloxane end-capped polyimides, which were actinic with the disiloxane equilibration reaction, was the aforementioned as that of the polyimides acquired from DiSXDA and m-phenylenediamine. Here, alone bottle alteration temperature (Tg) by cogwheel scanning calorimetry was appear about the backdrop of these polyimides. In addition, the atomic weight of the polyimide acquired from endo-DiSXDA and m-phenylenediamine was low, and alike the Tg was not reported.
Thus, it is advantageous to analyze endo- from exo-structures back synthesizing trisiloxane-containing tetracarboxylic dianhydrides, as apparent in Scheme 1. It is additionally important to analyze the accord amid the anatomy and backdrop of polyimides acquired from these tetracarboxylic dianhydrides.
For hydrosilylation to amalgamate alicyclic tetracarboxylic dianhydrides, endo-NBA (mp 166.5–167.5 °C), HMTS (Shin-Etsu Chem., Tokyo, Japan; LS-8130), Platinum Circuitous (Sigma-Aldrich, St Louis, MO, USA; Platinum(0)−1,3-divinyl–1,1,3,3-tetramethyldisiloxane complex, band-aid in xylene, 2% Pt) as the agitator and toluene as the bread-and-butter were commercially accessible and acclimated afterwards actuality refined. For the amalgam of polyimides, 4,4′-oxydianiline (ODA), 2-hydroxypyridine as the agitator and 1,2-dichrolobenzene as the bread-and-butter were additionally commercially accessible and acclimated as commercially formulated. In addition, acetone and booze were acclimated for bottomward the polyimides, 1-methyl–2-pyrrolidinone was acclimated as the bread-and-butter for advancing poly(amic acid), and N,N-dimethylacetamide was acclimated as the bread-and-butter for advancing polyimide films; these were additionally commercially accessible and acclimated as commercially formulated. The exo-NBA (mp 148.0–149.5 °C), which was accessible through the thermal isomerization of endo-NBA, was actinic as declared in the literature.7
The melting credibility of the dicarboxylic anhydrides and tetracarboxylic dianhydrides were abstinent application a capillary-type accoutrement at a heating bulk of 2 °C min−1. The bendability of exo-TriSXDA was abstinent application a rotational cone-plate-type EH-viscometer by Tokyo Keiki Inc., Tokyo, Japan. The apparatus of hydrosilylation admixture and the abstention of tetracarboxylic dianhydrides were angled by gel alteration chromatography (GPC) able with polystyrene gel columns (Hitachi Chem., Hitachi-shi, Japan; Gelpack GL-A110, two 500 mm columns in series, with a Mw exclusion absolute of ca. 1500), and a Hitachi L-300 RI detector was acclimated with tetrahydrofuran as an eluent at a breeze bulk of 1.0 ml min−1. Infrared (IR) spectra were acquired with a Varian 3100FT-IR spectrometer (Varian, Palo Alto, CA, USA) by attenuated absolute assimilation (ATR) method. Basal analyses were performed with an Elementar vario MICRO cube (Elementar, Hanau, Germany). The nuclear alluring resonance (NMR) spectra were recorded application tetramethylsilane as an centralized accepted in CDCl3 on a Bruker BioSpin AV400M (Bruker BioSpin, Rheinstetten, Germany; 1H NMR: 400 MHz). The number- and weight-average atomic weights (Mn and Mw) of the polyimides were angled by GPC able with polystyrene gel columns (Hitachi Chem.; Gelpack GL-R440, GL-R450 and GL-400M in series) and a Hitachi L-300 RI detector, and application tetrahydrofuran at a breeze bulk of 2.0 ml min−1. The arrangement was calibrated application polystyrene standards at allowance temperature. A thermomechanical assay was agitated out with a Seiko TMA/SS-6200 (Seiko, Chiba-shi, Japan) in compactness access at a heating bulk of 10 °C min−1. Cogwheel scanning calorimetry was performed with a Seiko DSC-6200 at a heating bulk of 10 °C min−1 in air. A thermogravimetric assay was fabricated with a Seiko TG/DTA-6200 at a heating bulk of 10 °C min−1 in air. Ultraviolet–vis spectra of the polyimide films were recorded on a Hitachi U-3310 spectrometer. Automated backdrop were abstinent with a Shimadzu AGS-5kNG (Shimadzu, Kyoto, Japan) with a 5 mm min−1 cartoon speed. Measurements were performed at ambient altitude for blur specimens (10 mm wide, 20 mm continued and 20–30 μm thick), and the after-effects of at atomic bristles samples were averaged.
Synthesis of meso and racemic isomers of endo-TriSXDA were appear in the antecedent paper.5 The amalgam of exo-TriSXDA is declared as follows: exo-NBA (65.66 g, 400 mmol) and toluene (260 g) were placed in a 1 l, four-necked, round-bottomed flask, able with a alluring stirrer, a 50 ml bottomward funnel, a nitrogen basin and a thermometer. Back the temperature of the acknowledgment admixture accomplished to 55 °C, 1.566 g of the Pt agitator band-aid (Pt: 0.161 mmol) was added to the flask, and HMTS (41.69 g, 200 mmol) was dripped for 2 h into the flask. The acknowledgment admixture was maintained at 55 °C for 1 h. A GPC assay accepted that the acknowledgment had been completed, abrogation no exo-NBA, HMTS or their intermediates (because HMTS reacted with one atom of exo-NBA) in the mixture. Afterwards cooling to the allowance temperature, activated carbon was added to the admixture to achromatize and abolish the catalyst. The achromatic clarify had no bright precipitation. Afterwards drying, a awful adhesive aqueous (99.2 g, 185 mmol, yield: 92.5%) with the bendability of 38.4 Pa • s at 40 °C was obtained. The abstention was 99.5% by GPC analysis.
Results of basal assay on C24H36O8Si3 (formula weight: 536.79) were as follows: the affected ethics of C and H were 53.70% and 6.76%, respectively, and those of abstinent ethics were 53.33% and 6.75%, respectively. The ν-values (ATR, cm−1) of the IR spectra of tetracarboxylic dianhydrides were as follows: endo-TriSXDA meso isomer; 1848 and 1772 (C=O), 1258 (Si-CH3), 1080 and 1063 (Si-O-Si), and 900 (C-O-C), endo-TriSXDA racemic isomer; 1857 and 1777 (C=O), 1255 (Si-CH3), 1082 and 1048 (Si-O-Si), and 903 (C-O-C), exo-TriSXDA; 1864 and 1774 (C=O), 1257 (Si-CH3), 1074 and 1034 (Si-O-Si), and 901 (C-O-C). Actinic about-face ethics of 1H NMR spectra (400 MHz, CDCl3) were declared in Amount 1 and Table 2.
The polyimides were actinic with the one-pot adjustment declared in the antecedent paper.4 The afterward were placed into a 100 ml, four-necked, round-bottomed flask, able with a automated stirrer, a Dean–Stark trap, a nitrogen basin and a thermometer, forth with tetracarboxylic dianhydride (5.368 g, 10.00 mmol), ODA (2.002 g, 10.00 mmol), 2-hydroxypyridine (0.230 g) and 1,2-dichrolobenzene (52.20 g). The admixture was acrimonious at 100 °C for 30 min until the monomers and the agitator were absolutely dissolved. The admixture was again acrimonious to 179 °C and refluxed at this temperature for 4 h.
["557.75"]
Haloalkanes, also known as halogenalkanes and as alkyl halides ... | draw all the structural isomers for the molecular formula c3h7brAfter actuality cooled, the band-aid was caked while actuality agitated into 500 g of booze to accelerate a polyimide. The polyimide was again attenuated in acetone (50 g). Booze was dripped boring while actuality agitated into the acetone band-aid until it afar into two layers. The aerial band was removed by decantation, and booze was added to the lower band to accelerate a polyimide. By repeating this procedure, polyimides with the adapted atomic weight were prepared.
Next, the able polyimide was attenuated in the N,N-dimethylacetamide solution. The assimilation was 25%. The polyimide blur was able by casting the band-aid assimilate a bottle bowl and again heating at 65 °C for 30 min, and at 165 °C for 15 min. Afterwards cooling, the bottle bowl was absorbed in baptize and the polyimide blur was bald off in water.
All the polyimides appropriately actinic accept the aforementioned atomic formula, (C36H44N2O7Si3)x and the affected ethics of C, H and N were 61.68%, 6.33% and 4.00%, respectively. The after-effects of basal analyses and atomic weight of the anniversary polyimide were as follows: endo-TriSXDA meso isomer/ODA polyimide: C=61.17%, H=6.31% and N=3.86%; Mn=19 800 and Mw=31 900. The endo-TriSXDA racemic isomer/ODA polyimide: C=61.05%, H=6.31% and N=3.92%; Mn=15 700 and Mw=27 500. The exo-TriSXDA/ODA polyimide: C=61.25%, H=6.26% and N=3.91%; Mn=76 500, Mw=110 000. The ν-values (ATR, cm−1) of anniversary polyimide was as follows: endo-TriSXDA meso isomer/ODA polyimide: 1773 and 1707 (C=O), 1499 (Ph), 1376 and 1168 (C-N-C), 1237 (br, Ph-O-Ph), 1034 (br, Si-O-Si). The endo-TriSXDA racemic isomer/ODA polyimide: 1778 and 1707 (C=O), 1499 (Ph), 1376 and 1168 (C-N-C), 1237 (br, Ph-O-Ph) and 1033 (br, Si-O-Si). The exo-TriSXDA/ODA polyimide: 1775 and 1707 (C=O), 1500 (Ph), 1378 and 1177 (C-N-C), 1239 (br, Ph-O-Ph) and 1034 (br, Si-O-Si). Actinic about-face ethics of 1H NMR spectra (400 MHz, CDCl3) were declared in Amount 3 and Table 2.
N-phenylimide was acquired from endo-TriSXDA meso isomer (10 mmol) and aniline (40 mmol), with the aforementioned adjustment as that acclimated for polyimide synthesis. Afterwards cooling, the acknowledgment band-aid was caked into a 1:1 (by weight) admixture of baptize and methanol. The resultant blurred aerial band of band-aid was removed, and the balance aniline and 1,2-dichrolobenzene were removed from the lower pale-yellow band by exhaustion beverage to aftermath a anemic yellowish-brown burnished solid of endo-TriSXDA meso N-phenylimide. The crop was 79.6%. The affected elementary compositions of C, H and N of C36H46N2O6Si3 were 62.94%, 6.75% and 4.08%,respectively, and the agnate abstinent ethics were 62.13%, 6.69% and 3.92%, respectively. The ν-values (ATR, cm−1) of IR spectrum were as follows: 1773 and 1706 (C=O), 1497 (Ph), 1371 and 1174 (C-N-C), 1256 (Si-CH3) and 1032 (br, Si-O-Si). Actinic about-face ethics of 1H NMR spectrum (400 MHz, CDCl3) were declared in Amount 4 and Table 2.
In the aforementioned manner, a anemic yellowish-brown burnished solid of exo-TriSXDA N-phenylimide was produced. The crop was 92.6%. After-effects of analyses for C, H and N of this admixture were 62.30%, 6.69% and 3.97%, respectively. The ν-values (ATR, cm−1) of IR spectrum were as follows: 1773 and 1702 (C=O), 1499 (Ph), 1378 and 1183 (C-N-C), 1256 (Si-CH3) and 1035 (br, Si-O-Si). Actinic about-face ethics of 1H NMR spectrum (400 MHz, CDCl3) were declared in Amount 4 and Table 2.
The amalgam of exo-TriSXDA/ODA poly(amic acid) is declared as follows: exo-TriSXDA (6.321 g, 11.78 mmol), ODA (2.358 g, 11.77 mmol) and 1-methyl–2-pyrrolidinone (49.2 g) were placed in a 100 ml, four-necked, round-bottomed flask. The acknowledgment admixture was maintained at 30 °C for 4 h. The band-aid was caked into baptize of 300 ml to accelerate a poly(amic acid). A agglomeration of poly(amic acid) was attenuated in acetone (40 g), and then, acetone band-aid was dripped boring into baptize while actuality agitated. Powdered poly(amic acid) was broiled at allowance temperature for 5 h by exhaustion (80 Pa). The crop was 61.6%. The affected elementary compositions of C, H and N of (C36H48N2O9Si3)x were 58.67%, 6.56% and 3.80%,respectively, and agnate abstinent ethics were 57.85%, 6.49% and 3.74%, respectively. The ν-values (ATR, cm−1) of IR spectrum were as follows: 3324 (br, O-H), 1703 (br, C=O), 1532 (N-H), 1499 (Ph), 1256 (Si-CH3), 1229 (Ph-O-Ph) and 1035 (br, Ph and Si-O-Si). The 1H NMR spectrum (400 MHz, acetone-d6) is apparent in Amount 3.
The hydrosilylation of endo- and exo-NBA proceeded stoichiometrically afterwards any byproducts, as accepted by GPC analyses. Comparing the acuteness of endo- and exo-NBA, it was begin that the exo-NBA acknowledgment was completed in a beneath aeon (9 h vs 3 h), admitting the closing accepting bisected the bulk of agitator (822 p.p.m. vs 402 p.p.m.: molar arrangement [Pt]/[NBA]) and a lower acknowledgment temperature (90 °C vs 55 °C). The appreciably college acuteness of exo-NBA comparing with endo-NBA agreed with the address on the hydrosilylation of endo- and exo-NBA with dimethylchlorosilane beneath the aforementioned conditions, in which the time to complete the acknowledgment for exo-NBA is 30 min or less, in adverse to 48 h for endo-NBA.8 According to the accession paper, the lower action of the endo-NBA was due to the allegation in the everyman alone atomic alternate (LUMO) and its anemic π-acceptor alternation with the platinum atom.9
As declared in the introduction, the endo-TriSXDA was disconnected into two types of crystals. The bright of lower melting point was accepted to be the racemic isomer by X-ray analysis, and that of college melting point was anticipation to be a meso isomer according to the acknowledgment mechanism. On the contrary, exo-TriSXDA, which was an acutely awful adhesive aqueous at allowance temperature, showed no assurance of condensate alike afterwards 3 years standing. From the bulk of yield, this is accepted to be a admixture of meso and racemic isomers.
Figure 1 shows the 1H NMR spectra of the tetracarboxylic dianhydrides. The amplitude of the ambit 0.00–0.15 p.p.m. is scaled up. The allegation of the protons in the amount is based on the after-effects of the Oak Ridge thermal ellipsoid artifice affairs (ORTEP) of X-ray analysis5 and allegory the two-dimensional spectra of absurd accustomed affluence bifold breakthrough alteration agreement (INADEQUATE), heteronuclear distinct breakthrough adherence and nuclear overhauser accessory spectroscopy. The spectra of meso and racemic isomer of endo-TriSXDA were begin to be about the same, and the alone aberration lies with the methyl accumulation protons of the centermost silicon in the accomplished field. The abstracts absorbed to these methyl groups represent their actinic about-face values. The two methyl groups of the meso isomer are nonequivalent; therefore, these protons were empiric as two abstracted peaks. On the added hand, those of the racemic isomer are equivalent. Therefore, these protons were empiric as a distinct peak.
And then, added after-effects of analyses for the NMR spectra were as follows. The H6a proton (i.e., methylene proton upfield) is in the exo-position of the norbornane arena for endo-TriSXDA, admitting it is in the endo-position for exo-TriSXDA. The two methyl accumulation protons (i.e., –CH310 and –CH311) affirmed with the ancillary silicon abide abreast the chiral centermost (i.e, no. 5 carbon). Therefore, these protons appearance altered actinic about-face values. From the accord amid these protons and the norbornane arena protons for the NOESY spectra, it is accepted that the silicon atom does not circle freely.
The after-effects of polymerization and precipitation are abbreviated in Table 1. As the repetitions of precipitation application acetone and booze increased, the crop of polyimides decreased. The accord amid the crop of all polyimides as logarithmic amount and the cardinal of precipitations are apparent in Amount 2a. A acceptable beeline accord can be apparent (correlation accessory r=0.970). Amount 2b shows the accord amid Mn and polydispersity (Mw/Mn) of polyimides. As the amount indicates, Mn added with again precipitation and Mw/Mn approached against 1.0. In addition, college assimilation and exo-structure produced the college Mn polyimides.
["298.76"]
structural isomerism | draw all the structural isomers for the molecular formula c3h7brWith commendations to the blur accumulation of polyimides, endo-polyimides from both meso and racemic isomers maintained the blur anatomy until centermost through the dehydration process. However, back the dehydration temperature exceeded the Tg, the endo-polyimides developed abundant accomplished cracks, preventing the accumulation of films. This is apparently attributable to a change in anatomy consistent from atomic movements at temperatures aloft the Tg. This abnormality additionally corresponds to the agee or baloney of a repeating assemblage structure, which is inferable via the NMR assay as mentioned beneath and the best abiding structures of tetracarboxylic dianhydrides from breakthrough actinic adding as mentioned in the aftermost section.
In the IR spectra of three polyimides, the ample assimilation abreast 3300 cm−1 based on the O-H accession beating of carboxyl accumulation was not empiric at all.
Figure 3 shows the 1H NMR spectra of the polyimides and exo-TriSXDA/ODA poly(amic acid) as contrast. The poly(amic acid) was abstinent with hexadeuteroacetone as solvent, because it is baffling in deuterochloroform. The amplitude of the ranges 0.00–0.20 and 6.6–7.7 p.p.m. is scaled up.
The spectrum of poly(amic acid) is acutely circuitous compared with the spectra of polyimides. The acumen is because of the actuality of isomers, which alter in the position area the amide and the carboxyl accumulation joins the norbornane ring. The methyl accumulation protons accept the three times college acuteness than the carboxyl accumulation proton and are accessible to be observed. However, there is not the methyl accumulation protons advancing from poly(amic acid) in the spectra of polyimides. In addition, the actuality of the carboxyl accumulation proton was investigated, but there was not the bright aiguille in the downfield added than 8 p.p.m.
Thus, it is accepted that the imidization was completed.
The three spectra of the polyimides in Amount 3 were all altered to anniversary other. The methyl accumulation protons of the centermost silicon in the endo-TriSXDA meso isomer/ODA polyimide (endo-meso polyimide) presented two acutely abstracted peaks. The aberration in actinic about-face amount amid the peaks was 0.011 p.p.m., which was beyond than the aberration for the endo-TriSXDA meso isomer. The methyl accumulation protons of the centermost silicon in the endo-TriSXDA racemic isomer/ODA polyimide (endo-racemic polyimide) showed the aforementioned aiguille as the endo-TriSXDA racemic isomer. For the exo-TriSXDA/ODA polyimide (exo-polyimide), the H2 and H3 protons were confused against the upfield to overlap with the H4 proton, but the methyl accumulation proton showed a altered actinic about-face amount from the endo-polyimides; this was additionally the case for the tetracarboxylic dianhydride. From these results, it can be assured that the polyimides maintained the anatomy of the tetracarboxylic dianhydrides.
The allegory in detail of the actinic about-face ethics of the protons amid the tetracarboxylic dianhydrides and the polyimides reveals that the actinic about-face ethics of protons added than the methyl, H2 and H3 protons additionally changed. The changes in actinic about-face ethics are advised to be a aftereffect of the transformation of protons into a polyimide, which causes the change in cyberbanking and alluring careful state. To affirm the above-mentioned speculation, N-phenylimides of endo-TriSXDA meso isomer and exo-TriSXDA were actinic as archetypal compounds. The 1H NMR spectra and changes in actinic about-face ethics are apparent in Amount 4 and Table 2. Comparing actinic about-face ethics amid the N-phenylimide and polyimide of exo-TriSXDA, the amount changes occurred alone in the H1, H6b and H7a protons. For the endo-TriSXDA meso isomer, however, such changes occurred in best of the protons. Therefore, it can be accepted that the changes in the actinic about-face amount were acquired not alone by imidization, or a change in the cyberbanking state, but additionally by polymerization, which apparently generated agee or baloney in the anatomy of the repeating assemblage of a polyimide. It additionally explains why endo-polyimides did not appearance the aerial atomic weight.
The solubility of the polyimides was activated qualitatively in several solvents and the after-effects are abbreviated in Table 3. All the polyimides were baffling in booze and afar into two abstracted layers in toluene. However, they attenuated readily in the added solvents.
The Tg by cogwheel scanning calorimetry and the 5% weight accident temperature (Td5) by thermogravimetric assay of endo-polyimides are apparent in Table 4. There are no differences in the ethics of thermal backdrop amid the meso and racemic isomers.
The exo-polyimides had acceptable blur formability in adverse with endo-polyimides alike back Mw was 56 200. Because they are acrid in acetone, polyimides of assorted Mw were able by repeating the apportioned precipitation. Table 5 shows the characteristics of the acquired exo-polyimides.
Many of the appropriate ethics abide about banausic by Mw. However, the amount of addendum at breach beneath compactness testing added with Mw, extensive a connected amount back Mw became 88 000 or higher.
["343.38"]
structural isomerism | draw all the structural isomers for the molecular formula c3h7brDespite the change in addendum with Mw, the amount of compactness backbone did not change, because the addendum accomplished the crop point at about 7% elongation. In added words, compactness backbone is equated with crop strength, and addendum is equated with breach strain.
As apparent in the table, the Tg of the exo-polyimide was 10–15 °C college than that of the endo-polyimides. This aftereffect is allusive to the ahead appear case of the endo- and exo-polyimides, which use DiSXDA and m-phenylenediamine for repeating structural unit, area the Tg amount of 187 °C was the aforementioned for the endo- and exo-polyimides.6 The acumen of the aforementioned Tg for endo- and exo-polyimides of m-phenylenediamine may appear from the adamant allocation abutting to dimethylsiloxane chain. Thus, the Tg of the polyimides may be mainly angled by the micro-Brownian motion of the adjustable dimethylsiloxane chain.
On the added hand, the polyimides advised in this cardboard are actinic from ODA, which has an ether band as angled bond. Comparing with polyimides actinic from m-phenylenediamine mentioned above, the sizes of the adamant allocation are small. In adverse to acerb angled adamant allocation of endo-polyimide, the adamant allocation of the exo-polyimide is extended. As a result, the polymer alternation of the exo-polyimide calmly takes an continued structure. Thus, the exo-polyimide may accept a denser ample anatomy compared with endo-polyimides, and the Tg may additionally become college due to the furnishings of the adjoining polymer chain.
The above-mentioned aftereffect agrees with the address by Matsumoto et al,10 in which the ethics of Tg of polyimide actinic application either norbornane-2,3-endo; 5,6-exo-tetracarboxylic dianhydride as angled anatomy and norbornane-2,3-exo; or 5,6-exo-tetracarboxylic dianhydride as continued anatomy with 1,3-bis(4-aminophenoxy)benzene were evaluated, and the Tg of the closing (225 °C) was appear to be 14 °C college than that of the aloft (211 °C).
Also, as apparent in Table 5 of automated properties, the college Mw resulted in the college elongation. The adjustable blur formability of exo-polyimides may appear from the aerial addendum due to the continued polymer structure. The modulus and addendum in Table 5 are three times college than endo-polyimide, for which the modulus, backbone and addendum were appear to be 0.56 GPa, 52 MPa and 7.9%,4 respectively, admitting accession cardboard appear that the modulus of endo-polyimide estimated from the backbone and addendum is 1.6 GPa,11 which is about the aforementioned amount in Table 5.
Figure 5 shows the ultraviolet–visible manual spectra of the polyimides. The films for altitude were able by dehydration on a bottle bowl at 80 °C for 30 min. The altitude of the endo-meso polyimide was acutely difficult because the blur was fragile. The absolute amicableness was 290 nm for both endo-meso and exo-polyimide films, and they became cellophane at aloft 350 nm. However, the exo-polyimide showed a college accuracy at about 300 nm.
The above-mentioned essentials are as follows: (1) the synthesizing action of endo-TriSXDA is added acute than exo-TriSXDA; (2) the changes in the actinic about-face amount of endo-polyimide were acquired not alone by imidization, but additionally by polymerization; (3) the atomic weight of endo-polyimides is lower than exo-polyimide; (4) the endo-polyimides are inferior to adeptness to anatomy a film.
It is anticipation that these after-effects are due to the atomic anatomy of tetracarboxylic dianhydrides as calmly illustrated in Scheme 1. To accept the added reasonable structure, the best abiding structures were acquired from breakthrough actinic adding application the Gaussian 09 software implementing the B3LYP anatomic with the 6–31 G(d) base set.
Figure 6 shows the anniversary optimized anatomy of exo- and endo-TriSXDA meso isomer. The two anhydride groups of exo-TriSXDA are amid at the ends of molecules, and the atomic anatomy is extended. On the added hand, the anhydride groups of endo-TriSXDA are amid closely, and the atomic anatomy is spherically shrunk. The anatomy of endo-TriSXDA is acutely altered from that apparent in the Scheme 1. Thus, the application about the atomic anatomy is advantageous to accept the backdrop of the endo- and exo-polyimides.
The exo-TriSXDA actinic through the hydrosilylation of exo-NBA and HMTS was a awful adhesive liquid, but by contrast, endo-TriSXDA from endo-NBA were crystal. Polyimides actinic from these tetracarboxylic dianhydrides and ODA maintained the aboriginal stereo structure. The exo-polyimide had the accomplished adequacy to anatomy film, enabling the barometer of abounding characteristics. On the added hand, in the case of endo-polyimides, alone thermal characteristics were able to be abstinent because of their poor film-formability. The endo-meso and endo-racemic polyimides showed the aforementioned Tg and Td5. In the case of exo-polyimide, best of those ethics were connected and irrespective of the Mw amount back the Mw exceeded 56 000, except for the addendum at break, which added with Mw and accomplished a abiding amount back Mw exceeded 88 000. Comparing the characteristics of the endo- with exo-polyimide, it was begin that the Tg of the closing was college than the former, and carnality versa apropos Td5. It can be assured that the aloft after-effects are acquired by the aberration in endo- and exo-TriSXDA structures.
["931.2"]
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