Preparing Polymer Maleimides

Methoxypolyethylene glycol maleimide has been prepared at ambient temperature by reacting the corresponding polyethylene oxide with A-methoxycarbonyl- maleimide. Since malimide derivatives are ordinarily prepared at 140°C, this ambient temperature imidization procedure dramatically broadens the scope and utilization of this reaction. 

A solution of methoxypolyethylene glycol (0.0025 mol) dissolved in 350 ml of CH2CI2, and A-methoxycarbonylmaleimide (0.0051 mol) was stirred at ambient temperature for one hour and then treated with 1 ml of A,A-diisopropylethylamine. The mixture was stirred overnight at ambient temperature and concentrated by 

TheStep 1 product (10.0 g) was dissolved in 100 ml of acetonitrile containing 10 ml of Al,Al-diisopropyl-ethylamine and stirred for 48 hours at ambient temperature. The solution was concentrated by distilling off 80 ml of solvent and 8.5 g of product isolated by precipitating in diethyl ether. The product was 93.5% maleimide-fiinctionalized. 

The succinimidyl analogue, (I), of the current invention was previously prepared by Harris [1]. 

In an earlier investigation by the author [2] the reagent 4-chlorobutyaldehyde diethyl acetal, (II), was used to convert methoxypolyethylene glycol into the corresponding aldehyde, which was then used as a conjugate for lysozyme, (111), as illustrated below. 

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As already mentioned, aromatie polymers are thermally stable but aliphatic portions of them are not as thermally stable. Typical maleimide resins have aliphatic units. This is inevitable because the Michael addition was used to prepare the maleimide-based oligomers. On the other hand, if an adhesive consists of a linear thermoplastic polymer, it is not usable at temperatures above its softening temperature. Introdueing chemical crosslinking is one way to prevent thermal weakening of a material. 

Phosphonitrilic polymers are self-extinguishing or fire-retardant. This led to the development of flame- and heat-resistant polyimide composites that are prepared from maleimide-substituted phosphazenes. The maleimide group is used for crosslinking. The substituted phosphazene can be illustrated as follows ... 

To prepare PEG-maleimide (PEG-MI), PEG methyl ether (Me-PEG) is reacted with (XXIII) in the presence of DCC and DPTS (see Problem 12.10) in CH2CI2 solution at room temperature for 12 h. On the other hand, PMMA-maleimide (PMMA-MI) is prepared by ATRP of MMA in toluene using (XVIII) as the initiator and Cu(I)Cl/PMDETA catalyst system. After the polymerization at 40°C for 3 h, the reaction mixture is passed through a basic alumina column to remove the catalyst and precipitated into hexane to recover the polymer (PMMA-MI). 

Similar approaches have also been used in the field of dendritic polymers. Calderon et al. (2009) prepared polymer-drug conjugates from dendritic polyglycerol and maleimide-bearing prodrugs (Tyagarajan et al., 2003 ... 

The condensation reaction between MA and aliphatic or aromatic polyamines has been used to prepare a large number of bismaleimides - - - and trismaleimides. """- "" Polystyrene has been treated with A-chloromethyl-maleimide, using a mild Friedel-Crafts procedure, to prepare polymer with pendant maleimide residues.Poly(vinyl alcohols) and alternating styrene-MA copolymer or polymers with pendent epoxide residues " have been converted to polymers with pendent maleimide moieties. All these multifunctional maleimides may be polymerized thermally, with peroxides, UV light, and y rays to obtain heat-resistant coatings or lami-... 

Phosphorus containing poly(maleimide-amines) were synthesized from N,N -bisdichloromaleimido-3,3 -diphenyl alkylphosphine oxides and aromatic diamines or piperazine [144]. The polymers prepared from piperazine are soluble in DMF, DM AC, DMSO, etc., but have poor thermal stability and flame retardancy. 

Medina et al. (1) photodimerized maleimide derivatives, (I), as a method for preparing semitelechelic silicone hydrogel polymers useful as for lens coatings as illustrated in Eq. (1). 

From time to time, synthetic transformations are reported that appear to be particularly convenient One such is the procedure described by Paul Hanson of the University of Kansas (Tetrahedron Lett. 44 7187,2003) for the conversion of an alcohol to the amine. The iminc 2, easily prepared by the addition of maleimide to furan, couples under Mitsubobu conditions with the 1 to give the imide 3, contaminated with the usual impurities from the condensation. The crude imide 3 smoothly polymerizes under Ru metathesis conditions to give polymeric 3, from which the impurities are easily washed away. Exposure of the washed polymer to hydrazine then liberates the pure free amine 4. 

As before, the homopolymer forming reaction involved the generation of an o-quinoidimethane from benzocyclobutene which in turn reacted with the double bond of a maleimide functionality on a second monomer to give chain extended AB material via a Diels-Alder pathway. The polymers prepared to date using this type of approach have been shown to have excellent thermal and mechanical properties and have been considered as potential candidates for use as matrix resins for advanced composites. This area has been investigated by the researchers at both the Air Force Wright Laboratories and the Dow Chemical Co. 

AB maleimide benzocyclobutene monomers and polymers have also been actively studied and developed by researchers at the Dow Chemical Co. The first AB maleimide type benzocyclobutene monomer prepared and polymerized by Kirchhoff was the benzocyclobutenyl maleamic acid 106 [6]. The detailed synthesis of 106 is shown in Fig 44. 

Of all of the AB benzocyclobutene maleimide homopolymers prepared, 114a appeared to have the best combination of thermal and mechanical properties as well as ease of fabrication (Table 21). This monomer/polymer was used as a... 

A variety of routes for incorporation of the succinimide group into a polymer backbone are provided by the use of bis(maleimide) monomers (8 Scheme 5). Examples include Michael addition of diamines or dithiols (or H2S) to produce poly(imides) (9) (B-80MI11101), and photopolymerization (via the triplet state) to prepare cyclopolymers (10) (73PAC213) having molecular weights of about 30 000. 

Aza-2,4-cyclopentadienone and 3-aza-2,4-cyclopentadienone are two reactive intermediates (75AG38) whose existence has been demonstrated by using the three-phase test. The precursor polymers for both compounds have been prepared (36) from maleimide, which was reduced with LiAlH4 and linked to the sulfonic polymer, and (39) by reaction between (37) and (38) (88JA4017 91JOC5417). 

FR 2612195 (French) 1988 Thermally stable polymers from bismaleimides, siloxane diamines and optionally maleimide-termi-nated siloxanes Rhone-Poulenc Chimie, Fr. R Barthelemy, Y Camberlin Heat-resistant maleimide-termi-nated siloxane Thermally stable polymers were prepared by co-curing MDA based bismaleimides and male-imide-terminated siloxanes. Michael addition with amino-terminated siloxanes and MDA was also utilized. 

Three unique di-diene have been utilized by Meek (9, 10) in the preparation of Diels-Alder copolymers. Reaction of 1,8-diphenyl-octatetraene with ftts-maleimides in refluxing chloroform for several days affords high yields of polymers with softening temperatures well over 300°, but low intrinsic viscosities. The copolymerization of 1,5-di(9-anthryl)-l,4-pentadiene-3-one and anthralazine with fo s-maleimides employs the diene nature of anthracene to obtain polymers with... 

The t-BOC protected copolymers were prepared both by copolymerization of the t-BOC protected hydroxyphenylmaleimide monomer with styrene and by modification of preformed phenolic copolymers of various molecular weights as shown in Scheme I. In both cases the copolymer compositions were foxmd to be 1 1 based on NMR results and elemental analyses. The NMR and IR spectra obtained from copolymers from both routes were identical. The 13C and IH NMR spectra of the modified polymer are shown in Figures 1 and 2. These data substantiate the completeness of the protection reaction of the preformed phenolic copolymer. The copolymers are presumed to be predominately alternating since these comonomers represent an example of the classic general alternating copolymerization case of an electron rich comonomer (styrene) and an electron poor comonomer (N-substituted maleimide) (13). 

Polymaleimide is prepared by free-radical polymerization of maleimide in the presence of divinylbenzene (.5%) or N,N -methylenebisacrylamide (5-10%) as cross-linking agents. PNCS is obtained by addition of chlorine in carbon tetrachloride to a suspension of the polymer in aqueous sodium hydroxide solution,... 

The sulfa drug A -[4-sulfamido-A -(5-methyl-3-isoxazolyl)phenyl]maleimide 610, prepared from maleic anhydride and 4-amino-A -(5-methyl-3-isoxazolyl)benzensulfonamide, was polymerized using benzoyl peroxide as a free radical initiator. The polymer showed significant antifungal activity toward both Candida albicans and A. niger <2002EPJ551>. 

Relies and Schluenz (8) have reported the preparation of poly(maleimide-ethers) by using bisphenols and bisdichloromaleimides. These polymers were soluble in dimethylformamide (DMF) and dimethylsulfoxide (DMSO) and gave tough flexible films. Phosphorus-containing poly(maleimide-amines) have been reported to have poor thermal stability and little flame retardation (9). 

As part of an ongoing program to prepare and study new, water soluble polymers, attention was focused on the possible radical copolymerization of 4,7-dihydro-l,3-dioxepins with maleic anhydride (MA) and maleimides. 

With the incorporation methodology of the maleimide unit, Lohmeijer et al. [224] were able to synthesize terpyridine-telechelic PS (Scheme 40, 6). They utilized a terpyridine-functionalized maleimide (Scheme 40, 5) that replaced the nitroxide chain end of PS (Scheme 40, 4). The polymer obtained would be of great value to prepare ABA metallo-supramolecular triblock copolymers. 

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