Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
  • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
  • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
  • C08G73/1003—Preparatory processes
  • C08G73/1007—Preparatory processes from tetracarboxylic acids or derivatives and diamines
  • C08G73/1028—Preparatory processes from tetracarboxylic acids or derivatives and diamines characterised by the process itself, e.g. steps, continuous
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
  • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
  • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
  • C08G73/1003—Preparatory processes
  • C08G73/1007—Preparatory processes from tetracarboxylic acids or derivatives and diamines
  • C08G73/1028—Preparatory processes from tetracarboxylic acids or derivatives and diamines characterised by the process itself, e.g. steps, continuous
  • C08G73/1032—Preparatory processes from tetracarboxylic acids or derivatives and diamines characterised by the process itself, e.g. steps, continuous characterised by the solvent(s) used
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G73/00—Macromolecular compounds obtained by reactions forming a linkage containing nitrogen with or without oxygen or carbon in the main chain of the macromolecule, not provided for in groups C08G12/00 - C08G71/00
  • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
  • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors

Definitions

• the invention relates to the preparation of crystalline polyimides by solvothermal synthesis.
• Polyimides are valuable materials for various applications. Their synthesis is usually carried out by polycondensation of diamines with dianhydrides in solution, in the melt or even in a solid state. Surprisingly, it was found several years ago that - despite the elimination of water during the condensation reaction - even water can be used as a solvent for the polyimide synthesis when so-called “hydrothermal conditions” prevail, including a reaction under pressure at temperatures above 100 ° C. (See Hodgkin et al., "Water as a Polymerization Solvent-cyclization of Polyimides: Le Chatelier Confounded", Polym. Prep. (American Chemical Society, Division of Polymer Chemistry) 41, 208 (2000), and WO 99/06470).
• COF covalent organic frameworks
• the aim of the invention was the development of an economical process for the production of highly pure, highly crystalline polyimides which are as pure as possible.
• This object is achieved by providing a process for the solvothermal synthesis of crystalline polyimides by solution polymerization of monomers in a suitable solvent by mixing the solvent and the monomers and heating the mixture under pressure to temperatures above the respective boiling point at atmospheric pressure, characterized in that Substantially completely crystalline polyimides can be prepared by
• the solvent is heated to solvothermal conditions, after which the monomers are added to initiate the reaction, or a2) the monomers are mixed with the solvent and the mixture is heated to solvothermal conditions within 5 minutes, the reaction temperature T R being kept in a solid state during the polymerization under the polymerization temperature or the polymerization temperature T P of the monomers;
• step a2) the polymerization is carried out at a reaction temperature T R which is at least 5 ° C, more preferably at least 10 ° C, below the T P to obtain as fully as possible crystalline polyimides.
• step a1) of the process according to the invention therefore no limitation of the reaction temperature is required.
• reaction temperature in the customary common heating according to step a2) of the process according to the invention is, of course, in diametrical contradiction to the accepted doctrine according to which the imidation reaction is to be carried out at the highest possible temperatures (Dao 1999, supra, Dao 2007, supra).
• the present invention is not limited to the use of diamines and di- anhydrides as monomers, but it can also higher-value amines and / or anhydrides are used, such as tri- or tetraamines or anhydrides.
• higher-valent monomers are even preferred according to the invention.
• the reaction mechanism in the polycondensation of higher-valent monomers or of mixtures of di- and higher-valent monomers and the principle of the invention are, of course, essentially the same as for divalent educts, for which reason the latter examples are used in the later examples for illustration purposes.
• stoichiometric salts (monomer salts, "AH salts") having a molar ratio between diamine and dianhydride of 1: 1 are formed in a step a) preceding additional step from the monomers to reduce the proportion of unreacted monomers in to keep the polyimide as low as possible.
• AH salts stoichiometric salts
• salts having other molar ratios corresponding to the valence of the monomers are obtained, ie approximately at a ratio of 3: 2 when diamines are combined with trianhydrides (or vice versa dianhydrides with triamines), etc.
• the solvent is limited in the process of the invention only in so far as the solubility of the monomers or of the stoichiometric salt thereof should be sufficiently low therein and, above all, the boiling point is below the T P of the two monomer components.
• preference is given to using water or else one or more alcohols or a mixture of water and alcohol (s) as solvent, in particular water, so that the present invention, in particularly preferred embodiments, a process for the hydrothermal synthesis of polyimides provides.
• an aromatic diamine and / or an aromatic tetracarboxylic dianhydride is / are preferably used in the present invention. Even more preferably, both components are aromatic, since on the one hand this increases the rigidity of the polymer chains, which promotes crystallization, and on the other hand reduces the solubility in the inventively preferred solvents water and alcohol.
• the monomer used is a stoichiometric salt of an aromatic diamine and of an aromatic tetracarboxylic dianhydride or of higher aromatic amines and anhydrides.
• the process of the invention comprises the separate heating of the solvent to solvothermal conditions and the subsequent addition of the monomers to the hot solvent, since such an in-solution migration of the monomers before reaching the solvothermal conditions is completely excluded.
• the joint heating of monomers and solvent as rapidly as possible in some cases may also be preferred over a1).
• Fig. 1 is the TGA curve of the monomer mixture according to Brunei et al. (so.).
• Fig. 2 is the XRD pattern of the polyimide obtained in Example 1 of the invention.
• Fig. 3 is a SEM photograph of the polyimide of Example 1 of the invention.
• Fig. 4 is the XRD pattern of the polyimide obtained in Example 3 of the invention.
• Fig. 5 is an SEM photograph of the polyimide of Example 3 of the invention.
• Fig. 6 is the XRD pattern of the polyimide obtained in Example 4 of the invention.
• Fig. 7 is the XRD pattern of the polyimide obtained in Example 5 of the invention.
• Fig. 8 is the XRD pattern of the polyimide obtained in Example 6 of the invention.
• Fig. 9 is the XRD pattern of the polyimide obtained in Example 8 of the invention.
• Fig. 10 is the XRD pattern of the polyimide obtained in Example 9 of the invention.
• Fig. 11 is the XRD pattern of the polyimide obtained in Example 10 of the invention.
• Fig. 12 is the XRD pattern of the polyimide obtained in Example 11 of the invention.
• PMA pyromellitic acid, benzene-1, 2,4,5-tetracarboxylic acid
• PMDA pyromellitic dianhydride, benzene-1, 2,4,5-tetracarboxylic dianhydride
• PPPDI poly (p-phenylene pyromellitic diimide)
• PPBTDI poly (p-phenylenebenzophenone tetracarboxylic acid diimide)
• PBBTDI poly (p-biphenylenebenzophenonetetracarboxylic acid diimide)
• PBTPPDI poly (benzenetri (p-phenylene) pyromellitic diimide)
• the monomer salt was distilled in 15 ml. Water, placed in a non-stirred autoclave and heated to HT conditions and finally to 200 ° C within 4.5 min. After 1 h at this reaction temperature, the autoclave was rapidly cooled to room temperature and the PPPDI formed was filtered off, washed with distilled water and dried in vacuo at 40 ° C overnight.
• XRD powder XRD
• complete crystallinity of the product which was present in the form of two solid crystalline phases, ie no amorphous contents, was observed, the degree of crystallinity ⁇ 0 ⁇ thus being> 99% shows the XRD pattern of the polyimide obtained SEM showed a very homogeneous, ordered morphology of the resulting PPPDI, which is further evidence of the extremely high degree of crystallinity
• Figure 3 shows the SEM uptake of the polyimide.
• Example 1 The procedure of Example 1 was substantially repeated except that the monomer salt was formed from 8.72 g of PMDA and 4.33 g of PDA in 400 distilled water. This monomer salt (T P 205 ° C.) was subsequently reacted in a stirred reactor in an autoclave to HT conditions within 4 minutes and finally likewise if heated to 200 ° C and the product is isolated as in Example 1 and dried. The purity and crystallinity of this PPPDI determined by means of IR and XRD were in accordance with the product from Example 1: ⁇ 0 ⁇ > 99%.
• the high rigidity of the resulting polyimide is crucial for this high degree of crystallinity of the resulting PPPDI, since the repeating units in the polymer molecule are largely planar due to mesomeric effects.
• Example 2 Analogously to the procedure of Example 1 were 0.48 g (1, 5 mmol) of BTDA in 15 ml of dist. Water with 0, 1 1 PDA with stirring - but reacted at room temperature - to the monomer salt [H 2 PDA 2+ BTA 2 ], whose T P was determined by TGA at 149 ° C and then in an autoclave in 15 ml of water without stirring heated to HT conditions and finally to 140 ° C within 5 min and then polycondensed for 12 h to the polyimide PPBTI.
• Example 3 Analogously to the procedure of Example 3 were 0.48 g (1, 5 mmol) of BTDA in 15 ml of dist. Water with 0.22 g of Bz with stirring to the monomer salt [H 2 Bz 2+ BTA 2 " ] reacted whose T P was determined by TGA with 172 ° C and then in non-stirred autoclave in 15 ml of water within 4.5 It was then heated to HT conditions and finally to 160 ° C.
• Example 3 was substantially repeated, but heating was by means of microwave radiation, so that the hydrothermal conditions were reached after less than 2 minutes, and the polymerization reaction was essentially complete after only 1 h.
• Fig. 7 shows the powder XRD pattern of the obtained dried PPBTDI.
• the areas under the curve of the crystalline peaks and the underlying Gaussian curve give a degree of crystallinity ⁇ 0 ⁇ of about 93%, which is thus a whole 31 percentage points above the 62% of the product from example 3.
• the significantly faster microwave heating - 2 min in Example 5 instead of 4 min in Example 3 - thus caused a significant increase in crystallinity by 50%, as apparently even lower levels of the monomer salt could go into solution before HT conditions were reached ,
• Fig. 8 shows the powder XRD pattern of the obtained dried PBBTDI.
• the areas under the curve of the crystalline peaks and the underlying Gaussian curve give a degree of crystallinity ⁇ 0 ⁇ of about 80%, which is thus a full 19 percentage points higher than the 61% of the product from example 4.
• Example 2 was essentially repeated, except that the monomer salt was suspended in 400 ml of ethanol instead of in water for polymerization.
• the reaction (after heating within 4.5 min on HT conditions and finally to 200 ° C) and workup were also carried out analogously to Example 2.
• Example 8 Preparation of Crosslinked Polyimide Poly (benzenetri (p-phenylene) romellitic diimide), PBTPPDI, using microwave radiation
• Example 3 The procedure of Example 3 was essentially repeated, except that 0.06 g (0.3 mmol) PMDA with 0.07 g (0.2 mmol) TAPB to the monomer salt [(H 3 TAPB 3+ ) 2 (PMA 2 " ) 3] were reacted, whose T P was determined by TGA at 152 ° C and then in the non-stirred autoclave in 15 ml of water by means of microwaves within 2 min to HT conditions, and finally heated to 140 ° C and thereafter for 12 hours to polyimide PBTPPDI was polycondensed.
• the monomer salt was prepared according to Example 1 a), but in a 10-fold approach.
• the salt thus obtained was distilled in 100 ml.
• Water was dispersed, and the dispersion was transferred to a high-pressure steel pipette, which was connected to a stirrer equipped with a 1 liter steel reactor, but separated by a valve from the reaction chamber, in the 400 ml dist. Water were submitted.
• the apparatus was placed in an autoclave and the water in the reaction chamber under the appropriate autogenous pressure to 200 ° C heated. Upon reaching this reaction temperature, the valve was opened and the monomer dispersion was preheated by inert gas pressure in less than 30 seconds Solvent injected.
• Example 1 The purity and crystallinity of this PPPDI determined by IR and XRD were consistent with the product of Example 1 (the XRD pattern is shown in Figure 10). There were no vibrations of the monomers or the monomer salt and no amorphous shares recognizable, so that a degree of crystallinity ⁇ 0 ⁇ was found by nearly 100%.
• reaction temperature need not be kept in a solid state below the polymerization temperature T P of the monomers, although in some cases this may nevertheless be preferred.
• the invention thus provides an improved process for the preparation of polyimides by solvothermal synthesis which provides products of significantly higher crystallinity than was possible in the prior art.

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• 2015
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