Vol. 3, No. A, Rloi~eriiber--Deceriiher1970
this shift is -0.7 kcal for Ia and -2.0 kcal for Ib. These shifts were reduced t o 0.0 for poly(viny1benzophenone) and -0.7 for I b when the spectra were recorded from iheir films, where all of the spectra are about 1-2 kcal lower than in organic glasses. Quantum yields for the sensitized photoisomerization of cis- and trans-stilbene were measured in degassed benzene solutions using light of 366-nm wavelength. The results for the monomeric models have been reported elsewhere.b The results for the polymeric sensitizers are reported in Table 111 along with a summary of the monomer values. These results show that the polymers poly(viny1benzophenone) and poly(pnaphthoylstyrene) sensitize the isomerization of stilbene with the same eficiency as d o the corresponding models. However, poly(wnaphthoy1styrene) is less efficient than are its corresponding models in the case of the trans -+ cis process. Furthermore, the inefficiency for the anaphthoyl polymer is related t o the chain length of the polymer. Thus, when polystyrene of molecular weight 4700 was treated with a-naphthoyl chloride, the resultant polymer had a & of 0.45 + 0.01 while the polymer prepared by naphthoylation of a polystyrene with molecular weight 900 had +t of 0.49 0.01. The inefficiency of the a-naphthoylated polymers in
*
AMINIMIDES 71 5
sensitizing the trans -+ cis isomerization of stilbene could be explained o n the basis of the steric requirements of the a-naphthoyl group. Such steric requirements could force the polymer into a configuration which would bury the internal chromophores and make them inaccessible t o acceptor molecules. However, & is normal for poly(a-naphthoylstyrene) and this implies that all of the excitation energy in this polymer is available for sensitization. Thus, it appears that the inefficiency in pt must be due t o a n induced inefficiency in the use of the excitation energy by the sensitized molecule of trans-stilbene. We believe this is the result of the positive volume of activation noted by Fischer4 for the trans -+ cis process. Accordingly we envision the excited trans-stilbene molecules t o be confined for a time in a polymeric cage which restricts their rotation. Thus, some of the excited stilbene molecules would decay t o the ground state before proceeding to the twisted triplet, which is responsible for isomerization. The fact that & i s not lower for poly(anaphthoylstyrene) may be explained by the lack of a volume of activation for the cis + trans process. It is believed that this explanation is more than just a local visocisty effect since the /3-naphthoyl polymer would also be expected t o show such a n effect.
Aminimides. VIII.’” Synthesis and Homo- and Copolymerization Studies of 1,l ,1-Trimethylacrylylhydrazinium Chloride and 1,1,1-Trimethylmethacrylylhydrazinium Chlorideib B. M. Culbertson* and R. E. Freis Research Center, Ashland Chemical Companj,, Minneapolis, Minnesota Receiced June I O , 1970
55420.
ABSTRACT: The monomers l,l,l-trimethylacrylylhydraziniumchloride (11) and l,l,l-trim:thylmethacrylylhydrazinium chloride (111) were synthesized and shown to readily homo- and copolymerize with a variety of other vinyl monomers to produce copolymers containing pendent quaternary residues (-CONHNR3-X-). The resultant polymers were treated with base to provide “reactive polymers” with pendent aminimide groups (CON-N-R3). Since molecules with aminimide residues suffer a carbon-nitrogen migration reaction on heating, the aforesaid aminhide polymers were thermolyzed both in solution and the solid phase to provide unique, “reactive polymers” with pendent secondary or tertiary isocyanate groups. The reactivity ratios of each monomer (M,) with styrene (MY) were determined: monomer 11, r, = 0.46, r? = 0.58; monomer 111, rl = 0.23, r2 = 0.51. The Alfrey-Price Q and e values were also calculated: Q = 0.69, e = 0.34 and Q = 0.61, e = 0.66, respectively.
S
tudies in several laboratories have shown that both aliphatic and aromatic compounds with ammonium acylimine residues of the type -CON-NaR3 suffer a carbon-nitrogen migration reaction during pyrolysis,”-I yielding tertiary amines and isocyanates. In a
*
To whom correspondence should be addressed. ( I ) (a) Presented in part to the Polymer Division at the 2nd Central Regional Meeting of the American Chemical Society, Columbus, Ohio, June 5, 1970; (b) for paper IV in this series, see B. M . Culbertson and R. c. Slagel, J . POb’m..%is, Parr A - 1 , 6, 363 (1968). (2) S. Wawzonek and R. G. Gueldner. J . Om. Chem.. 30. 3031 (1965). (3) M. S. Gibsor and A. W. Murry, J . Chem. SOC.,880 (1965). (4) W . J. McKillip, L . M . Cleniens, and R . Hnugland, Can. J . C h ~ w45, , 261 3 (1967).
prior publication, Ih we described the preparation and polymerization properties of trimethylammonium-Nmethacryloylimine (I, trimethylamine methacrylimide). The cited work demonstrated that monomers such as I CH3
I
CH%=CCON-N+(CH3)3 I
are highly useful for preparing a wide variety of reactive polymers. The present work was undertaken t o prepare and t o study Of the homo- and copolymerization characteristics of 1,1,1 -trimethylacrylylhydrazinium chloride
71 6 CULRERTSON AND FREIS
(TI) and l,l,l-trimethylmethacrylylhydraziniumchloride (111) and to compare the polymerization behavior of monomers I1 and I11 with I. R
I
CH*=CCONHN(CH,),+ C1-
11, R = H 111, R CH, Since molecules with residues of the type -CONHNR:,+X- may be treated with base t o obtain compounds with the aminimide moiety (-CON-N+R8),2-r it is readily apparent that monomers such a s IT a n d 111 should also have utility in the preparation of reactive polymers with pendent quaternary, aminimide, or isocyanate groups. Experimental Section
The nmr spectra were obtained on a Varian A-60A spectrometer using tetramethylsilane as an internal standard, except with deuterium oxide as a solvent where 3-trimethylsilyl-1-propanesulfonic acid was used as a standard. The infrared spectra were recorded on a Perkin-Elmer 237B grating spectrophotometer. The melting points are uncorrected. Elemental analyses were determined by Huffman Laboratories, Jnc., Wheatridge, Colo. Differential thermal and thermogravimetric analyses were obtained on the Du Pont 900 DTA and 950 TGA units, under nitrogen at a heating rate of 5"/min. Gel permeation chromatography (gpc) results were obtained on a Waters Model 200 unit using tetrahydrofuran solvent at room temperature and 4-ft columns of 106, 5 X lo4,103,250, and 60 A porosity Styragel resins. Inherent viscosities (Tinh) were determined at 30" using 0.5 g of polymer/100 ml of solvent. The thin layer chromatography (tlc) method employed silica gel coated plates, methanol solvent, and I* developer. The basic ion exchange resin used was prepared from Fischer Scientific's Rexyn 201-resin. The resin, as received from Fisher, was treated with aqueous potassium hydroxide, washed with water until washings were neutral, and washed several times with the same solvent used in the ion exchange work, i.e., acetone, methanol, tetrahydrofuran, or N,Ndimethylformamide. The expression wet acetone, wet methanol, etc., means the solvent used contained cn. 5 % by weight of water. The per cent isocyanate determinations were accomplished in the following manner. A polymer sample of known weight was treated in solution with an excess of alkylamine. After reaction at room temperature for a few minutes, during which time the amine reacted with the isocyanate moiety, the excess amine was titrated with a standard HCI solution, using bromocresol green indicator. Knowing the weight of polymer used, equivalents of amine added, and equivalents of HCl used, the weight per cent of NCO on the polymer birckbone was calculated. I. Monomers. l,l,l-Trimethylacrylylhydrazinium Chloride (11). Methyl acrylate, 344 g (4.0 mol), was added with stirring to a 3-1. round-bottomed flask containing 900 ml of deionized water and 240 g (4.0 mol) of unsymmetrical dimethylhydrazine. The considerable exotherm was controlled by reflux condensers. After stirring for 12 hr the solution was evaporated to a pale yellow solid which was recrystallized from acetone-methanol to give a 437 g (92 %) yield of 1,l-dimethylpyrazolinium 3-oxide ( l ) , mp 89.5-90.5 (1it.j mp 90.5-91 "). The carbonyl absorption in the infrared ( 5 ) N. P. Zapevalova, L. A. Ovsyannikova, and T. A. Sokolova, 126. Akud. Nuirk S S S R , Srr. Khim., 12, 220 (1966).
Macromolecules
spectrum at 1585 cm-' was consistent with reported6 absorption for cyclic aminimides. The nmr spectrum (DMSO-d) showed a singlet at 6.85 ppm, triplets a t 7.39 and 6.20 ppm in a ratio of 3 :1 :1, respectively, Compound 1, 114 g (1.0 mol), was placed in a flask and heated iiz cacuo at 250". The material distilled at 120" (1.4 mm) and solidified upon cooling to afford a 70 g (62%) yield of 1 ,l-dimethyl-2-acrylhydrazine(2), mp 84" (lit,: mp 84"). Ir analysis showed absorption bands at 3220, 1675,1640, and 1555cm-I. A 2-1. glass-lined Parr bomb was charged with 650 ml of methyl alcohol, 100 g of 2; and cu. 100 ppm of 2,2-diphenyl-lpicrylhydrazyl. Methyl chloride was charged until the bomb pressure was 55 psi. The bomb was heated overnight at 70", cooled, and the volume reduced to ca. 200 ml. The product was precipitated with chloroform, washed with ether, and dried to obtain a 73 g (52%) yield of 3 (section 11), mp 194-195" (lit.' mp 195-196'). Ir analysis (mineral oil mull) showed absorptions at 3140, 1680, 1630, and 1555 cm-l. The nmr spectrum (DzO) showed a singlet at 6.22 ppm and multiplets at 4.01 and 3.60 ppm in a ratio of 9:2: I , respectively (the nitrogen proton exchanged with D,O). l,l,l-TrimethylmethacrylylhydraziniumChloride (111). To a solution of l,l,l-trimethylammonium-N-methacryloylimine (I) in absolute methyl alcohol was added excess hydrogen chloride cia a gas dispersion tube. The solution was stirred during the addition of the gas and the temperature maintained below 40' by an ice bath. The solution was reduced to nonvolatiles on the flash evaporator, redissolved in chloroform, and precipitated with benzene. Nearly quantitative yields of 111 were obtained: mp 139-139.5" (lit.* mp 139139.5"); ir absorption bands at 3130, 1635, 1670, and 1550 cm-1. Comonomers. The monomers styrene and methyl methacrylate were purified by distillation under nitrogen through a 12-in. Vigreux column immediately before use. The monomers butyl acrylate and hydroxyethyl acrylate were used as received from Rohm and Haas and Dow Chemical. 11. Solvents and Initiators. All of the solvents used were purified according to standard procedures. Azobisisobutyronitrile (AIBN) was purified by recrystallization from methyl alcohol. 111. Polymerization. A. Polymerization of l,l,l-TrimethylacrSlylhydrazinium Chloride (11). 1. Homopolymerization. A 60-ml serum bottle was charged with 5.0 g of 11, 10 ml of anhydrous methanol, and 5.0 mg of AIBN. The bottle was flushed with nitrogen, sealed. and placed in a shaker bath at 70 =t1" for 20 hr. The viscous, alcoholic solution was poured into 300 ml of vigorously stirred acetone. The white precipitate was collected and washed several times with acetone to obtain a 3.5 g ( 7 0 z yield) of polymer. After dissolving in methanol, reprecipitating with acetone, and drying iii C U C I I O , the polymer was shown to be free of monomer by tlc. The polymer exhibited an inherent viscosity of 1.56 in methanol. The infrared spectrum (film) exhibited the expected strong amide absorption bands at 3400,1700, and 1560 cm-'. A small sample of the polymer was dissolved in wet methanol and the solution fed through a column of basic ion exchange resin. The infrared spectrum (film) of the recovered and dried polymer exhibited the typical strong aminimide absorption band at 1570 cm-l and no bands at 3400, 1700, and 1560 cm-1. After heating in air at 150" (30 min), the infrared spectrum of the polymer exhibited a new strong band at 2260 cm-l and no band at 1570 cm- I. (6) W. J. Wadsworth, Jr., J . Org. Chem., 31,1704 (1966). (7) L. A. Svsyannikova, T. A. Sokolov'i, and N. P. Zaprvalova, Zh. Org. Khim., 4 (3). 459 (1968). (8) T. A. Sokolova, L. A. Ovsyannikova, and N . P. Zapevalova, ihid., 2 ( 5 ) , 818 (1966).
AMINIMDES717
_ _
~
Run no.
TABLE I REACTIVITYSTUDYOF MONOMER 11
_ _
Mol of I1
Mol of styrene
Mol % of I1 monomer feed
0.01 0.02 0.03 0.04 0.06 0.08 0.12 0.15 0.17
0.19 0.18 0 . I7 0 . I6 0.14 0.12 0.08 0.05 0.03
5.0 10.0 15.0 20.0 30.0 40.0 60.0 75.0 85.0
Ditkrential thermal analysis and TGA curve also showed that the polymer lost 47% of its weight from 125-200' (theory, 46.1 ;
