MALEIMIDE MODIFIED POLYPROPYLENE IMINE DENDRIMERS AND A PROCESS FOR THEIR PREPARATION
The invention relates to poIy(prσpylene imine) type dendrimers, which have been modified by means of a maleimide modification reaction with the nmine groups situated in the shell of the dendrimer, and a method for ιr_a__π__factι__ring the mentioned dendrimers. Maleimide modified poly(propyle_ιe muse) dendrimers can b used as crossϊinlcing agents, in coatings, adhesives and as a matrix material in composites.
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Treelike macromolecules with a highly branched struαcre and with a spherical shape constitute a family of pdymeis, which has been increasingly studied during recent years, These macromolecules having three-dimensional molecular architecture are referred to as dendritic polymers or dendrimers. Dendrimers differ significantly from
15 conventional linear oligo ers and polymers. Linear oligomers, which have sufficient molecular weight in order to be used e.g. in crosslmkable polyester resins, usually contain molecular chains with only two terminal functional groups in each molecule, while the structure of dendrimers is a compact spherical molecule with many blanches which cany a high number of terminal mncύoπal groups on each molecule. The
20 unique physical and chemical properties of dendrimers yields the compounds and products made from them interesting and special properties, as an example of them can be mentioned the exceptional and favourable rheolog al properties polyesters, such as low viscosity, when compared with linear oligomers. Dendrimers are usually marcufactuied by iterative synthesis in cycles, when in each stage die chemical and
25 physical properties of the molecule, such as size, shape, reactivity and solubility, can be adjusted- Oligomers with a strongly branched structure can be used in many applications, such as catalysts, in pharmaceutical industry, as carriers for drugs, in cosmetics industry, adhesives, coatings, composites, agricultural chemicals and as multifunctional crossl___ι ____g agents.
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A series of hypcrbranched (meth)acrylated polyesters with (_LiJ_forcnt number of tsrminal double bonds per molecule has been presented and methods for the manufacture thereof have been disclosed in tie patent application WO 96707688. This
publication discloses a hyperbran aed polyester of a polyol with 3 to 10 reactive hydroxyl groups and an aromatic polycaitooxylic anhydride with 2 to 4- carboxyl groups, each bydroxyl group of the polyol forming an ester linkage with one anhydride group of the polycarboxylic anhydride, and further glycidyl (meth)acrylate or allyl glycidyl ether forming ester linkages with the remaining carboxyl groups of the anhydride and free hydroxyl groups. Further, in the hyperbranched polyester, (meth)acrylic anhydride and/or an aliphatic carboxylic anhydride form ester linkages with free bydroxyl groups. The said hyperbranched polyesters can be used as resins which are curable by UN-radiation.
It is known to m_mufa__u_xe amine terminated dendrimers by using riiπτnτnobmaρe a a core molecule, to the primary amine groups of which two equivalent acrylonitriles (reaction A) are added by Micbael-addmon reaction, after which the catalytic reduction of nitrile groups to primary amine groups is made (reaction B), when the result is a dendrimer od the first generation having four primary amine cennmal groups. After this, die reaction series (A) and (B) is repeated 1 to 4 times, when finally a fifth generation molecule having amine terminal groups, is obtained. These polypropylene imine) dendrimers are commercially available, Astramol (DSM), in different generations and having amine tenninal groups or nitrile terminated groups.
Polyimide based t__£_mosemng resins have achieved great favour in the industry because of their many advantageous properties, especially their good physical properties in elevated temperatures and wet environment. The use of malfrnni if, especially bi_____c___eimides, in thexmosetting resins is known. Maleimide is a versatile reactive group, which can react by different mechanisms, which is especially advantageous in the crosslmbng of .mermosemng resins. The chemical reaction between amino group and maleic acid anhydride is well known fro the literature. aleimides can be manufactured from primary amines and maleic anhydride in the presence of an organic solvent like dimethyl fonnamide, dimethyl acetamide, acetone, toluene, mefhyleαe chloride, tetr__hydrofuxane or comparable either by using hearing or in the presence of acetic acid. Bisinaleimides are highly reactive resins, which can be
croslinked in many ways. This is a consequence of the attractive character of wo carbonyl groups of ττ.a.__vrτ»iti.. Bismaleides polymerise easily without any catalyst when heating mem over the melting point and as a result strongly crosslinked polymers with good thermal stability are achieved.
On the basis of what is said above it can be seen that there is an obvious need for macromolecules and especially oligomers, which have the exceptional properties of dendrimers, such as a compact spherical, structure and numerous functional tenninal groups, and the reactivitry of malsπriides.
The object of the invention are reactive maleimide modified polypropylene imine) dendrimers, a method to manufacture them and the usage of them.
Characteristics of the maleimide modified polypropylene imine) dendrimers, of the me rYJI tn τn_.τnιfam_τE_ f erη apd nf the n$age of hem are stated in f ie da s
It has been found that according to the invention the above mermoned aims can be reached and the polypropylene imine) type dendrimers can be customised especially to a crαsslmkable tbexmosetάπg resin by making the maleimide modification reaction with the amine groups situated on the shell of the dendrimer. As a starting material for the dendrimers according to the invention can be used polyφropyiene imine) dendrimers, which are commercially available having a tradeaame Astramol (DSM). It has been found at according to the invention branched multi-purpose ma.em.if... modified poly rαpylene imine) dendrimers can be manufactured to be used as starting materials for functionalised oligomeric and polymeric polyesters and poiyamides according to the following figure 1.
Figure 1
Polypropylene imine) dendrimer (I), which here is as an example a poly ropylene imine) dendrimer with four amine terminal groups, is let to react with maleic acid anhydride (β) in the presence of a solvent, After that the reaction mixture is heated up and the desired teiramaleimide is formed. In maleimide modification maleic acid anhydride reacts with die amine group forming a reactive maleimide ring.
According to the invention 5-50 mol%, favourably 10-20 mol5δ amount in excess 1. - 3. generation, favourably the first or..the second generation polypropylene imine) dendrimer, which has 4 or S amine terminal groups, is let to react with maleic acid anhydride in the presence of an inert solvent like τetrahydrofurane or methylεne chloride at 20-40 βC temperature, after which the temperature is slowly elevated to 50- 120 βC, favourably to 70-90 °C, and the mixing is continued. The crystallised product is separated by a suitable method, favourable it is filtered, washed up and dried
In the shell layer of the maleimide modified poly(propylene imine) dendrimer there exist highly reactive maleimide rings, which are able to react using many different mechanisms. As examples from them can be mentioned the polymerisation by heat, by free radical poly erisanon/crossliijking, when peroxides or azo compounds can be used as initiators, or by ion polymerisation using tertiary amides or imidazoles as catalysts or by copolymerisaπon with diene monomers and bisdienes.
Maleimide modified polypropylene imide) dendrimers according to the invention can be used in numerous different applications, from which can be mentioned thermosetfing plastics, coatings, inks, oil additives, adhesives, catalysts, composites and matrix materials for composites. The advantages of the dendrimers according to the invention are excellent reactivity, when they are especially good for multifunctional cxossliαl ng agents, and a simple manufacturing method
The following examples illustrate the compounds according to the invention and the method however not limiting the invention to them.
Example 1
Manufacture of tetra_______leimide polypropylene imine) dendrimer
Into a solution conramrπg 1,0 g (3,2 m ol) of t ' first generation polypropylene imine) deridrimer in 30 ml tetrahyάrofuranc, was added 20 mol9£ excess meaning 1,49 g (15,2 mmol) maleic acid anhydride in the room temperature. A white precipitate was immediately formed. After this the temperature was slowly increased to 70 °C and the mixture was agitated for 6 hours. The product was filtered and washed with a small amount of tetrahydrofu ane and dried in a vacuum at 40 ° during the night, when tetramaleiinide polypropylene imine) dendrimer was obtained as white powder. The yieldwas l,86 (92 %).
lH-NMR ( DsN): α = 1,75 (m. 4H, NC_H*CH_CH2CTfeN), 2,02 ( , 8H,
2,84 ( , 4H, NCHzC&CΞzCIW), 3,01 (t, 8H, NOfcCIfcCHiNR), 3,56 Cm, SH, NOI H fcNR). 6.66 (s, 2H, CHCH).
I3H-NMR (CsDsM): α = 24,09 NOt fcOi fc ), 25,78 (NCBCT:CH- ), 38,07 (NCH?CHιCH2NR), 51,56 (NCH HiCHzNE), 53,78
167,32X169,64 (NCOCHCHCON).