Synthesis and Radical Polymerization Behavior of Bifunctional Vinyl Monomer Derived from N-Vinylacetamide and p-chloromethylstyrene

Synthesis and Radical Polymerization Behavior of Bifunctional Vinyl Monomer Derived from N-Vinylacetamide and p-chloromethylstyrene TAKERU IWAMURA,* TOMOYUKI NAKAGAWA, TAKESHI ENDO Research Laboratory of Resources Utilization, Tokyo Institute of Technology, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan Received 23 September 2005; accepted 4 February 2006 DOI: 10.1002/pola.21381 Published online 14 March 2006 in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: The radical polymerization of N-(p-vinylbenzyl)-N-vinylacetamide (1) prepared by the reaction of N-vinylacetamide with p-chloromethylstyrene was carried out by using radical initiators such as AIBN or BPO in benzene, chlorobenzene, or bulk. As a result, poly 1 was successfully isolated by dialysis (yield, 10 36%). The crosslinking reaction of poly 1 was carried out at 60 100 8C for 8 h. By using a radical initiator such as AIBN or BPO (3 mol %), the crosslinking reaction proceeded (yield, 63 79%). Moreover, the crosslinking reaction of poly 1 proceeded at 100 8C without a radical initiator in 50% yield. VC 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2714 2723, 2006 Keywords: chemical modification; crosslinking reaction; N-vinylacetamide; p-chloromethylstyrene; radical polymerization INTRODUCTION Interest in N-vinylacetamide (NVA) and its derivatives has grown in recent years. Dawson et al. and Stackman et al. developed the synthetic procedure for NVA and its polymerization. 1 3 Akashi et al. reported the thermosensitive properties of the polymers derived from NVA and its derivatives. 4 11 Through further investigations of the synthetic process for NVA, they have examined the radical polymerization behavior of NVA and the application of poly(nvinylacetamide) to functional polymers. *Present address: Institute for Environmental, University of Shizuoka, 52-1, Yada, Shizuoka 422-8526, Japan. Present address: T. Endo, Department of Polymer Science and Engineering, Faculty of Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa, Yamagata 992-8510, Japan. Correspondence to: T. Endo (E-mail: tendo@poly.yz. yamagata-u.ac.jp), Vol. 44, 2714 2723 (2006) VC 2006 Wiley Periodicals, Inc. 2714 We have reported the chemical modification of vinyl monomer having amide moiety. The chemical modification of these vinyl monomers by isocyanates has been carried out to give the corresponding monomers in good yields. 12 16 Moreover, we have reported that the radical polymerization of enyne derivatives as bifunctional monomers proceeds through the specific 1,2-polymerization to give polymers having acetylene moieties in the side chain, regardless of the character of the substituents. 17 Modifications of monomers such as NVA carrying amidic hydrogen with alkyl halide under basic conditions may provide new bifunctional monomers and consequently new polymers having unique functions. In this article, we wish to describe the radical polymerization behavior of N-(p-vinylbenzyl)-N-vinylacetamide (1) derived from NVA and p-chloromethylstyrene. Monomer 1 has two vinyl groups that have different polymerizability. Thus, it is

POLYMERIZATION BEHAVIOR OF VINYL MONOMER 2715 Table 1. Radical Polymerization of 1 Run Initiator a Solvent Conc (M) Temp (8C) Time (h) Conv Yield M n (%) b (%) c (M w /M n ) d 1 AIBN Benzene 1.0 60 2.5 33 31 27000 (2.74) 2 BPO Benzene 0.1 80 2.5 10 10 3100 (1.42) 3 BPO Benzene 1.0 80 2.5 37 36 17000 (2.62) 4 BPO Benzene 1.0 80 5.0 e 59 Gel 5 BPO Benzene 1.5 80 2.5 e 22 Gel 6 BPO Benzene 5.0 80 2.5 e 80 Gel 7 BPO Benzene 10.0 80 2.5 e 91 Gel 8 BPO None 80 2.5 e 91 Gel a Initiator, 3 mol %. b Determined by 1 H NMR spectrum. c Isolated by dialysis. d Estimated by GPC, based on polystyrene standards; eluent, THF. e Not determined. attractive to examine the radical polymerization behavior of 1. Materials N-vinylacetamide, which was provided by Showa Denko Co., Ltd., was recrystallized from benzene. Benzene was purified sufficiently by shaking with conc. H 2 SO 4 until free from thiophene and then washed with saturated NaHCO 3 aqueous solution and water, followed by drying over CaCl 2. The thiophene-free benzene was dried over sodium metal and distilled under nitrogen atmosphere. Chlorobenzene was purified sufficiently by shaking with conc. H 2 SO 4, water, saturated NaHCO 3 aqueous solution, and water, followed by drying over CaCl 2. Other commercially available reagents were used without further purification. EXPERIMENTAL Measurements IR spectra were measured using a JASCO FT/ IR-5300 spectrometer. 1 H NMR and 13 C NMR spectra were obtained on a JEOL JNM-EX400 ( 1 H NMR, 400 MHz; 13 C NMR, 100 MHz) spectrometer. The 13 C CP-MAS solid-state NMR measurements were conducted on a JEOL GX- 270 operating at 67.94 MHz. Electron ionization mass spectra (EI-MS) were recorded by using a Shimazu GCMS-QP5050A equipped with DI unit. Gas chromatography analyses were carried out on a Shimazu GC-17A (DB-1-30 N-STD). Gel permeation chromatographic analyses were carried out on a Tosoh Co. HLC-8120 GPC system (TSK-GEL SUPER H4000 and TSK-GEL Table 2. Radical Polymerization of 2 a Run Initiator b Solvent Conc. (M) Temp. (8C) Conv. (%) c Yield (%) d 1 AIBN Benzene 1.0 60 0 0 2 AIBN PhCl 1.0 60 0 0 3 AIBN None 60 0 0 4 BPO Benzene 1.0 80 0 0 5 BPO PhCl 1.0 80 0 0 6 BPO None 80 0 0 7 DTBPO PhCl 1.0 120 0 0 8 DTBPO None 120 0 0 a Conditions Reaction time, 12 h. b Initiator, 3 mol %. c Determined by 1 H NMR spectrum. d Isolated yield.

2716 IWAMURA, NAKAGAWA, AND ENDO Scheme 1. Synthesis of monomer 1 and 2. SUPER H2000, THF as eluent, and an ultraviolet (UV) detector) using polystyrene as a standard. In the case of analyses of THF insoluble polymers, gel permeation chromatographic analyses were carried out on a Tosoh Co. HLC-8120 GPC system (TSK-GEL SUPER H4000 and TSK-GEL SUPER H2000, H 2 O containing 2- amino ethanol (0.20 M) and acetic acid (0.26 M) as eluent and an ultraviolet (UV) detector) using poly(ethyleneglycol) as a standard. Synthesis of N-(p-Vinylbenzyl)-N-vinylacetamide (1) To a benzene (25 ml) suspension of sodium hydroxide (3.53 g, 87.50 mmol), potassium carbonate (7.01 g, 50.65 mmol), and tetra-n-butylammonium hydrogensulfate (0.85 g, 2.50 mmol) in a 300 ml round-bottomed flask was added NVA benzene solution (2.13 g, 25.03 mmol/25 ml). The mixture was stirred at room temperature for 3 h under nitrogen atmosphere, and then p- chloromethylstyrene (5.80 g, 38.00 mmol) was added at 0 8C. After 24 h at room temperature, water (30 ml) was added into the reaction mixture. The resulting mixture was extracted with benzene. The organic phase was washed with saturated sodium hydrogen carbonate aqueous solution and water, dried over MgSO 4, and evaporated to dryness under reduced pressure. The crude monomer 1 as a pale yellow solid was isolated by chromatography on silica gel with hexane-acoet (2:1) as the eluent. The crude monomer 1 was dissolved into diethyl ether, and then the solution was added to charcoal. After the mixture was stirred for 10 min, the filtrate was evaporated to dryness under reduced pressure. The obtained white solid was recrystallized from diethyl ether. Yield 74%. mp. 63 64 8C; IR (KBr): 3086, 3053, 3009 (CH 2 ¼CH, C 6 H 5 ), 1664 (C ¼O), 1622 (C ¼O) cm 1 ; 1 H NMR (CDCl 3, 400 MHz) d: 2.18 (s, 3H 0.3, CH 3 ), 2.34 (s, 3H 0.7, CH 3 ), 4.30 (d, J ¼ 9.2 Hz, 1H 0.7, CH 2 ¼CH N cis), Figure 1. IR (KBr disk) (a) and 1 H NMR (CDCl 3 ) (b) spectra of monomer 1.

POLYMERIZATION BEHAVIOR OF VINYL MONOMER 2717 C 11 H 13 NO: C, 77.58%; H, 7.51%; N, 6.96%. Found: C, 77.48%; H, 7.53%; N, 6.98%. Scheme 2. Radical polymerization of monomer 1. 4.35 (d, J ¼ 15.6 Hz, 1H 0.3, CH 2 ¼CH N trans), 4.38 (d, J ¼ 9.2 Hz, 1H 0.3, CH 2 ¼CH N cis), 4.40 (d, J ¼ 15.6 Hz, 1H 0.7, CH 2 ¼CH N trans), 4.72 (s, 2H 0.3, CH 2 C 6 H 5 ), 4.86 (s, 2H 0.7, CH 2 C 6 H 5 ), 5.19 (d, J ¼ 10.8 Hz, 1H 0.7, CH 2 ¼CH C 6 H 4 cis), 5.23 (d, J ¼ 10.8 Hz, 1H 0.3, CH 2 ¼CH C 6 H 4 cis), 5.69 (d, J ¼ 17.6 Hz, 1H 0.7, CH 2 ¼CH C 6 H 4 trans), 5.72 (d, J ¼ 17.6 Hz, 1H 0.3, CH 2 ¼CH C 6 H 4 trans), 6.66 (dd, J ¼ 17.6 and 10.8 Hz, 1H 0.7, CH 2 ¼CH C 6 H 4 ), 6.68 (dd, J ¼ 17.6 and 10.8 Hz, 1H 0.3, CH 2 ¼CH C 6 H 4 ), 6.82 (dd, J ¼ 15.2 and 9.2 Hz, 1H 0.7, CH 2 ¼CH N ), 7.10 7.38 (m, 5H, C 6 H 5 ), 7.61 (dd, J ¼ 15.2 and 9.2 Hz, 1H 0.3, CH 2 ¼CH N ) ppm; 13 C NMR (CDCl 3, 100 MHz) d: 22.0, 22.4, 45.1, 48.5, 94.6, 95.2, 113.6, 114.1, 125.7, 126.3, 126.7, 127.0, 131.7, 133.2, 135.5, 136.1, 136.4, 136.6, 136.8, 169.5, 169.7 ppm; EI-MS: m/z 201 [M] þ ; Anal. Calcd for Radical Homopolymerization of 1 (Typical Procedure, Table 1, Run 3) Monomer 1 (300 mg, 1.55 mmol) and benzoyl peroxide (BPO, 11.3 mg, 0.03 mmol) were dissolved in benzene (1.55 ml) in a test tube, which was then degassed and sealed in vacuo. The reaction mixture was heated at 60 8C for 2.5 h and subjected to dialysis using a cellulose tube (pore size 20 lm). The tube was kept in contact with stirred methanol for 48 h, and then the content was evaporated to give a polymeric product (yield 110 mg, 36%). IR (Cast): 3013 (CH 2 ¼CH, C 6 H 5 ), 1672 (C ¼O), 1622 (C ¼O) cm 1 ; 1 H NMR (CDCl 3, 400 MHz) d: 1.09 2.30 (m, 6H, CH CH 2, CH CH 2, CO CH 3 ), 3.92 4.51 (m, 2H, CH 2 ¼CH N ), 4.51 5.08 (m, 2H, N CH 2 C 6 H 5 ), 5.95 7.98 (m, 5H, CH 2 C 6 H 5, CH 2 ¼CH N ) ppm; 13 C NMR (CDCl 3, 100 MHz) d: 22.2, 22.5, 40.0, 44.0, 45.1, 48.5, 94.5, 95.2, 125.3, 126.5, 127.6, 129.5, 131.9, 133.3, 134.2, 143.7, 169.5 ppm. Synthesis of N-Benzyl-N-vinylacetamide (2) To a benzene (25 ml) suspension of sodium hydroxide (3.50 g, 87.50 mmol), potassium carbonate (7.00 g, 50.65 mmol), tetra-n-butylammonium hydrogensulfate (0.85 g, 2.50 mmol) in a 300 ml round-bottomed flask was added NVA Figure 2. 1 H NMR (CDCl 3 ) (a) and 13 C NMR (CDCl 3 ) (b) spectra of poly 1.

2718 IWAMURA, NAKAGAWA, AND ENDO Figure 3. IR (Cast) (a) and 1 H NMR (CDCl 3 ) (b) spectra of monomer 2. benzene solution (2.13 g, 25.03 mmol/25 ml). The mixture was stirred at room temperature for 3 h under nitrogen atmosphere, and then benzyl bromide (6.41 g, 37.48 mmol) was added at 0 8C. After 24 h at room temperature, water (30 ml) was added to the reaction mixture. The resulting mixture was extracted with benzene. The organic layer was washed with a saturated sodium hydrogen carbonate aqueous solution and water, dried over MgSO 4, and evaporated to dryness under reduced pressure. Monomer 2 as a pale yellow oil was isolated by chromatography on silica gel with hexane-acoet (2:1) as the eluent. Yield 69%. IR (neat): 3086, 3007 (CH 2 ¼CH, C 6 H 5 ), 1676 (C ¼O), 1627 (C ¼O) cm 1 ; 1 H NMR (CDCl 3, 400 MHz) d: 2.18 (s, 3H 0.3, CH 3 ), 2.34 (s, 3H 0.7, CH 3 ), 4.33 (dd, J ¼ 9.2 and 1.2 Hz, 1H 0.7, CH 2 ¼CH cis), 4.38 (d, J ¼ 15.2 Hz, 1H 0.3, CH 2 ¼CH trans), 4.42 (d, J ¼ 9.2 Hz, 1H 0.3, CH 2 ¼CH cis), 4.46 (dd, J ¼ 15.2 and 1.2 Hz, 1H 0.7, CH 2 ¼CH trans), 4.79 (s, 2H 0.3, CH 2 C 6 H 5 ), 4.90 (s, 2H 0.7, CH 2 C 6 H 5 ), 6.87 (dd, J ¼ 15.2 and 9.2 Hz, 1H 0.7, CH 2 ¼CH ), 7.16 7.38 (m, 5H, C 6 H 5 ), 7.63 (dd, J ¼ 15.2 and 9.2 Hz, 1H 0.3, CH 2 ¼CH ) ppm; 13 C NMR (CDCl 3, 100 MHz) d: 22.0, 22.3, 45.2, 48.6, 94.5, 95.1, 125.5, 126.7, 126.9, 127.3, 128.4, 128.9, 131.7, 133.2, 136.0, 136.9, 169.5, 169.7 ppm; EI-MS: m/z 175 [M] þ ; Anal. Calcd for C 11 H 13 NO: C, 75.40%; H, 7.48%; N, 7.99%. Found: C, 75.14%; H, 7.40%; N, 7.08%. Radical Homopolymerization of 2 (Typical Procedure, Table 2, Run 1) Monomer 2 (190 mg, 1.10 mmol) and 2,2 0 -azobisisobutylronitrile (AIBN, 5.6 mg, 0.03 mmol) were dissolved in benzene (1.1 ml) in a test tube, which was then degassed and sealed in vacuo. After 12 h at 60 8C, the reaction mixture was poured into diethyl ether (ca. 100 ml). However, the expected poly 2 could not be obtained from the reaction mixture quantitatively. Copolymerization of 2 and NVA The copolymerization of 2 with NVA was performed under various feed ratios. Typically, 2, NVA, and AIBN (3 mol %) were dissolved in benzene in a test tube, which was degassed and sealed in vacuo. After 12 h at 60 8C, the reaction mixture was poured into diethyl ether and the precipitated polymer was dried in vacuo. The obtained copolymer compositions were determined by their 1 H NMR spectra. Copolymerization of 2 and Styrene The copolymerization of 2 with styrene was performed under various feed ratios. Typically, 2, styrene, and AIBN (3 mol %) were dissolved in benzene in a test tube, which was degassed and sealed in vacuo. After 12 h at 60 8C, the reaction mixture was poured into diethyl ether and the

POLYMERIZATION BEHAVIOR OF VINYL MONOMER 2719 Scheme 3. Radical polymerization of monomer 2. precipitated polymer was dried in vacuo. The obtained copolymer compositions were similarly determined by their 1 H NMR spectra. Radical Crosslinking of Poly 1 (Typical Procedure, Table 5, Run 3) Poly 1 (58.2 mg) and AIBN (1.4 mg, 0.29 mmol) were dissolved in chlorobenzene (0.65 ml) in a test tube, which was then degassed and sealed in vacuo. After 8 h at 60 8C, the reaction mixture was filtered. The obtained crosslinked polymer was purified by extraction with benzene, using the Soxhlet method (yield 36.7 mg, 63%). IR (KBr): 3090 (CH 2 ¼CH, C 6 H 5 ), 1671 (C ¼O), 1624 (C ¼O) cm 1 ; CP-MAS (67.9 MHz) d: 22.6, 40.2, 44.4, 45.6, 50.0, 51.3, 53.0, 54.1, 94.4, 126.7, 129.1, 134.2, 140.7, 142.8, 144.6, 147.3, 170.0 ppm. RESULTS AND DISCUSSION Figure 4. 1 H NMR spectra of monomer 2 at various temperatures (40 100 8C) in CDCl 3. Synthesis and Homopolymerization of 1 Monomer 1 was synthesized by a one-step reaction from NVA and p-chloromethylstyrene in 74% yield (Scheme 1). The IR spectrum of 1 showed two absorption bands at 1676 and 1624 cm 1 based on two carbonyl groups [Fig. 1(a)]. In the 1 H NMR spectrum, all the signals were observed due to the stereoisomer [Fig. 1(b)]. For example, the signals assignable to two methyl protons attributed to the acetyl group were observed at d 2.18 and 2.34 ppm because of the stereoisomer. The integral ratios of these methyl peaks are 30:70. The results of the polymerization are summarized in Table 1. The radical polymerization of 1 was carried out using BPO and AIBN as an initiator (Scheme 2). As a result, poly 1 was successfully isolated by dialysis in 10 37 % yields (M n ¼ 3100 27,000) (Table 1, Run 1 3). When the polymerization of 1 was carried out at 80 8C

2720 IWAMURA, NAKAGAWA, AND ENDO Scheme 4. Radical copolymerization of NVA and monomer 2. for 2.5 h, poly 1 was obtained in 37% yield (Run 3). However, when the reaction time was prolonged, the crosslinked polymer was obtained in 59% yield (Run 4). Moreover, when the 1 was stirred with more than 1 M at 80 8C for 2.5 h, the crosslinked polymers were also obtained in 22 91% yields (Run 5 8). The crosslinked polymer might be formed by higher concentration in the polymerization system. The 1 H NMR and 13 C NMR spectra of poly 1 are shown in Figure 2. In the 1 H NMR spectrum, the signals ascribable to vinyl group protons of NVA moiety were observed to be similar to those of 1 [Fig. 2(a)]. In the 13 C NMR spectrum of the poly 1 [Fig. 2(b)], the signals due to the vinyl group were observed at d 94.5, 95.2, 131.9, and 133.3 (g, d) ppm. Because the NVA moiety existed without the excess and deficiency in the NMR spectra of poly 1, the NVA moiety may not have high polymerizability. However, from the results of Runs 4 8 in Table 1, the NVA moiety may have high reactivity of the crosslinking. Table 3. Run Radical Copolymerization of 2 and NVA a 2 (mol %) Conversion of NVA (%) b M n (M w /M n ) c x/y d 1 0 100 68,000 (4.26) 100/0 2 20 92 19,000 (4.72) 97/3 3 40 82 12,000 (3.75) 97/3 4 60 81 6,700 (5.00) 95/5 5 80 80 4,800 (3.30) 93/7 6 100 79 4,700 (2.65) 91/9 a Conditions, AIBN (3 mol %); Solvent, benzene; 60 8C; 12 h. b Determined by gas chromatography. c Estimated by GPC, based on polystyrene standards; eluent, THF. d Determined by 1 H NMR spectrum. Synthesis and Homopolymerization of 2 Monomer 2 was prepared as a reference compound for 1. Monomer 2 was synthesized by the reaction of NVA and benzyl bromide in 69% yield (Scheme 1). The IR spectrum of 2 showed two absorption bands at 1624 and 1676 cm 1 based on two carbonyl groups [Fig. 3(a)]. In the 1 H NMR spectrum, the signals assignable to two methyl protons attributed to the acetyl group were observed at d 2.18 and 2.34 ppm because of the stereoisomer. The integral ratios of these methyl peaks are 30:70. Moreover, the signals assignable to two methylene protons attributed to the benzyl group were observed at d 4.79 and 4.90 ppm, and the integral ratios of these methylene peaks are 30:70. A possible speculation for the presence of the two kinds of peaks ascribable to an acetyl group might be a restraint of rotation at the N C ¼O group. Generally, in the case of disubstituted acetamides, the larger functional group on nitrogen prefers to be cis to carbonyl oxygen, which is smaller than the methyl group. 18 Therefore, the ratio of cis/trans might be 70:30. Additionally, the 1 H NMR spectra of 2 were measured at various temperatures (Fig. 4). The two kinds of methylene peaks that originated from benzyl group were observed at 40 8C. However, these peaks fused together at 60 100 8C. Consequently, the two peaks may be based on the stereoisomer. The polymerization of 2 was carried out at various temperatures for 12 h using a radical polymerization initiator (3 mol %) such as AIBN, BPO, and di-t-butyl peroxide (DTBPO) (Scheme 3). The conversion of 2 was determined by the 1 H NMR spectrum of the reaction mixture. However, the polymerization of 2 did not proceed under usual radical polymerization conditions (Table 2, Run 1 8). These results indicated that

POLYMERIZATION BEHAVIOR OF VINYL MONOMER 2721 Scheme 5. Radical copolymerization of styrene and monomer 2. NVA moiety of 2 did not undergo the radical polymerization. Since the benzyl group was introduced into NVA, the steric hindrance caused by benzyl group substituents may increase. As a result, the homopolymerization of 2 may not proceed. That is, this double bond may not have radical homopolymerizability. In the case of monomer 1, the crosslinking proceeded at high temperature or high concentration conditions (Table 1, Runs 4 8). The NVA moiety of poly 1, which was generated from 1, underwent crosslinking. In this case, the NVA moieties were fixed to the side chain of the poly 1. However, in the case of monomer 2, such an influence does not exist. From the above noted results, it is also supposable that monomer 2 does not have radical homopolymerizability. Copolymerization of 2 and NVA The radical copolymerization of 2 and NVA was carried out at 60 8C for 12 h using AIBN as an initiator under various feed ratios (Scheme 4, Table 3). The conversion of NVA was determined by the gas chromatography analysis of the reac- Table 4. Styrene a Run Radical Copolymerization of 2 and 2 (mol %) Conversion of Styrene (%) b M n (M w /M n ) c x/y d tion mixture. The conversion of NVA decreased as NVA increased. Copoly(NVA-2) was obtained as a diethyl ether-insoluble part. The number average molecular weights of these polymers were estimated by GPC. As a result, M n decreased as the amount of 2 increased. The copolymer compositions were determined by their 1 H NMR spectra, the y unit of copolymer increased as the amount of 2 increased. Consequently, monomer 2 might behave as a radical polymerization retarder in the copolymerization of 2 and NVA. Copolymerization of 2 and Styrene The radical copolymerization of 2 and styrene was carried out at 60 8C for 12 h using AIBN as an initiator under various feed ratios (Scheme 5, Table 4). The conversion of styrene was determined by the gas chromatography analysis of the reaction mixture. The conversion of styrene was not affected by the amount of 2. The number average molecular weights of these polymers, which were obtained as a diethyl ether-insoluble part, were almost unchanged. The copolymer compositions were determined by their 1 H NMR spectra. As a result, the expected copoly(st-2) could not be obtained. All of the obtained polymers were a homopolymer of styrene. Consequently, it seems clearly that the mono- 1 0 21 7800 (1.41) 100/0 2 20 25 8100 (1.42) 100/0 3 39 23 8200 (1.41) 100/0 4 79 28 7900 (1.35) 100/0 5 100 28 7900 (1.38) 100/0 a Conditions, AIBN (3 mol %); Solvent, benzene; 60 8C; 12 h. b Determined by gas chromatography. c Estimated by GPC, based on polystyrene standards; eluent, THF. d Determined by 1 H NMR spectrum. Scheme 6. Crosslinking reaction of poly 1.

2722 IWAMURA, NAKAGAWA, AND ENDO Table 5. Run Crosslinking Reaction of Poly 1 a Initiator (3 mol %) Temp (8C) Yield of Crosslinked Polymer (%) b reaction proceeded without radical initiator such as AIBN and BPO. Therefore, the NVA moiety may be an excellent crosslinking site. 1 None 40 0 2 None 60 0 3 AIBN 60 63 4 None 80 0 5 BPO 80 79 6 None 100 50 a Conditions Solvent, chlorobenzene; 8 h. b Isolated yield. mer 2 has poor radical copolymerizability with styrene. SUMMARY The monomer 1 having two polymerizable groups was synthesized by the reaction of NVA with p-chloromethylstyrene. The radical polymerization of 1 proceeded selectively at only a double bond, which was derived from styrene moiety. The crosslinking reaction of the resulting poly 1 was carried out at 60 100 8C for 8 h. By using radical initiators such as AIBN or BPO (3 mol %), the crosslinking reaction proceeded (yield: 63 79%). Moreover, the crosslink- Crosslinking Reaction of Poly 1 The crosslinking reaction of poly 1 was carried out at various temperatures for 8 h in chlorobenzene (Scheme 6, Table 5). By using the radical initiator such as AIBN or BPO (3 mol %), the crosslinked poly 1 were obtained in 63 or 80% yield (Runs 3 and 5), respectively. The crosslinking reaction did not proceed below 80 8C (Runs 1, 2, and 4) in the absence of the radical initiator, but the crosslinking of poly 1 proceeded at 100 8C (Run 6). The IR spectra of crosslinked poly 1 (Run 5) are shown in Figure 5. The IR spectrum of crosslinked poly 1 showed two absorption bands at 1674 and 1622 cm 1 based on two carbonyl groups. In the IR spectrum of crosslinked poly 1, the peak due to the double bond was small, while those attributable to the double bond in the linear polymer were observed at 3013 3015 cm 1. The CP-MAS and 13 C NMR spectra of crosslinked poly 1 (Run 5) are shown in Figure 6. In the CP-MAS spectrum of crosslinked poly 1, the signals ascribable to acetyl group were observed at 22.6 and 170.0 ppm similar to those observed in the case of the corresponding linear polymer. Furthermore, the signals assignable to the double bond, which was observed in a linear polymer, were not observed at d 94 95 ppm. As mentioned earlier, though the NVA moiety has neither the homopolymerizability nor the copolymerizability, the crosslinking reaction can be caused. Moreover, if poly 1 was heated to the high temperature (100 8C), the crosslinking Figure 5. IR spectra of crosslinked poly 1 (KBr disk) (a) and linear poly 1 (Cast) (b).

POLYMERIZATION BEHAVIOR OF VINYL MONOMER 2723 Figure 6. CP-MAS spectrum of crosslinked poly 1 (a) and 13 C NMR (CDCl 3 ) spectrum of linear poly 1 (CDCl 3 ) (b). ing reaction of poly 1 proceeded at 100 8C without any radical initiator in 50% yield. REFERENCES AND NOTES 1. Ben-Ishai, D.; Giger, R. Tetrahedron Lett 1965, 6, 4523. 2. Dawson, D. J.; Gless, R. D.; Wingard, R. E., Jr. J Am Chem Soc 1976, 98, 5996. 3. Stacman, R. W.; Summerville, R. H. Ind Eng Chem Prod Res Dev 1985, 24, 242. 4. Akashi, M.; Nakano, S.; Kishida, A. J Polym Sci Part A: Polym Chem 1996, 34, 301. 5. Chen, M.; Kishida, A.; Akashi, M. J Polym Sci Part A: Polym Chem 1996, 34, 2213. 6. Suwa, K.; Wada, Y.; Kikunaga, Y.; Morishita, K.; Kishida, A.; Akashi, M. J Polym Sci Part A: Polym Chem 1997, 35, 1763. 7. Suwa, K.; Morishita, K.; Kishida, A.; Akashi, M. J Polym Sci Part A: Polym Chem 1997, 35, 3094. 8. Suwa, K.; Morishita, K.; Kishida, A.; Akashi, M. J Polym Sci Part A: Polym Chem 1997, 35, 3377. 9. Kunugi, S.; Takano, K.; Tanaka, N.; Suwa, K.; Akashi, M. Macromolecules 1997, 30, 4499. 10. Chen, M.-Q.; Serizawa, T.; Akashi, M. Polym Adv Technol 1999, 10, 120. 11. Chen, C. W.; Akashi, M. Polym Adv Technol 1999, 10, 127. 12. Iwamura, T.; Tomita, I.; Suzuki, M.; Endo, T. J Polym Sci Part A: Polym Chem 1998, 36, 1491. 13. Iwamura, T.; Tomita, I.; Suzuki, M.; Endo, T. J Polym Sci Part A: Polym Chem 1998, 36, 1515. 14. Iwamura, T.; Tomita, I.; Suzuki, M.; Endo, T. Bull Chem Soc Jpn 1998, 71, 1137. 15. Iwamura, T.; Tomita, I.; Suzuki, M.; Endo, T. J Polym Sci Part A: Polym Chem 1999, 37, 465. 16. Iwamura, T.; Tomita, I.; Suzuki, M.; Endo, T. React Funct Polym 1999, 40, 115. 17. Ochiai, B.; Tomita, I.; Endo, T. Chem Lett 1998, 563. 18. Isbrandt, L.; Tung, W. C.-T.; Rogers, M. T. J Magn Reson 1973, 9, 461.