5원환카보네이트를 포함한 PDOMA의 합성과 공중합체인

MMA(methyl methacrylate)와 EA(ethyl acrylate)의 상용성 고찰

박 성영·김 경훈·박 대원·하 창식*

부산대학교 화학공학과

*부산대학교 고분자 공학과

Synthesis of PDOMA beraing cyclic carbonate and Miscibility of Its

Blends with Copolymers of MMA(methyl methacrylate)

and EA(ethyl acrylate)

S. Y. Park·K. H. Kim·D. W. Park·C. S. Ha*

Dept. of Chem. Eng., Pusan National University

*Dept. of Polymer Science and Eng., Pusan National University

1. Introduction

Carbon dioxide plays an important role in the global warm-up. An attractive strategy to deal with this situation is to convert CO2 into valuable substance. Consequently new technologies are being investigated to convert CO21) catalytically. The synthesis of 5-membered cyclic carbonates under mild conditions in the presence of metal halides or a Phase Transfer Catalyst(PTC) was also reported2). Of special interest are the reactions of CO2 with oxiranes or some polymers containing pendant epoxide groups, since they lead to the production of cyclic carbonates. These cyclic carbonates can be used as aprotic polar solvents, electrolytes for batteries and as sources for reactive polymer synthesis. In this work, poly(glycidyl methacrylate)(PGMA) was converted to a polymethacrylate bearing a five-membered cyclic carbonate group by the polymer reaction with carbon dioxide using a catalyst. However, a vinyl monomer bearing a cyclic carbonate group such as (2-oxo-1,3-dioxalane-4-yl) methyl methacrylate(DOMA) is extremely sensitive to the polymerization and difficult to handle. Thus, the quantitative polymer reaction of epoxide polymers with carbon dioxide can be the most effective method of obtaining cyclic carbonate polymers3). Blends of polymers bearing a cyclic carbonate group with some commercial polymers have been developed in this laboratory for more versatile application of the polymers.

In this work, therefore blends of PGMA and PDOMA copolymers with MMA-EA copolymers were also prepared. Miscibility of blends was investigated by using DSC, and the binary interaction model, as well as optical clarity test.

2. Experiment

Radical polymerization of GMA(40mmol) with DMSO(30ml) solvent was performed using azobisisobutyronitrile(AIBN)(5mg) as an initiator at 70oC for 10h under nitrogen atmosphere and then the solution was poured into distillation water to give a precipitate. Copolymerization of methyl methacrylate and ethyl acrylate with acetonitrile was performed by the same method as for polymerization of GMA. Two copolymers with different EA composition(2 and 5 wt%) in feed were prepared. Polymer was recovered using an excess of methanol and was purifed using chloroform/methanol reprecipitation.

PDOMA was synthesised from PGMA and CO2 using TOAC catalyst as shown in scheme 1.

Scheme 1. PDOMA Synthesis via Incorporation of

Carbon Dioxide into PGMA

The catalyst(5 mmol) was introduced to a 250ml three-neck pyrex reactor containing the mixture of 0.6g of PGMA and 30ml of DMSO, and the solution was heated up to a desired tempeature(100oC), the reaction was started by stirring the mixture under a  stream of CO2(10ml/min) and was continued for 24h.

Blends were prepared by solution casting. Polymer mixtures in weight fraction of PGMA and PDOMA of 1, 0.8, 0.6, 0.4, 0.2 and 0 were cast on glass plates, and all films were dried under vacuum for 3 days at room temperature.

3.Reslt and Discussion

1) Structure Identification of PDOMA from the Reaction of PGMA and           Carbon Dioxide

The reaction of PGMA with carbon dioxide was carried out at 100oC for 24h in DMSO using 0.05mmol of TOAC as a catalyst under atmospheric pressure. Conversion of epoxide to a five-membered cyclic carbonate group could be identified by FT-IR(Fig1). It was reported that the reaction rate was first order to the concentration of poly(GMA) and CO2, respectively, in our previous work. The reaction of PGMA with carbon dioxide was carried at 100oC. It is known that the rate-determining step of the epoxide-CO2 reaction involves nucleophilic attack of an anion to oxirane ring. High nucleophilic Cl- anion in an aprotic solvent is also known to enhance the attack of the anion to epoxides ring of PGMA. Thus, PDOMA can be synthesized easily by the polymer reaction of PGMA and carbon dioxide using these active catalysts. Since DOMA is an unstable monomer, the polymer reaction method is superior to the polymerization method to obtain PDOMA. The IR-spectrum of PGMA did not show an absorption peak at 910cm-1(c-o-c of oxirane), but the PDOMA exhibited an absorption peak at 1800cm-1(c=o of cyclic carbonate) on IR spectrum.

Figure 1. FT-IR spectram of PGMA and PDOMA

2) Syntheses of MMA-EA Copolymers

The comonomer content of synthesized polymers was identified by a 1H-NMR spectrum and the reactivity ratio evaluated by the extended Kelen-Tudos method. The reactivity ratio was found to be rMMA=1.83, rEA=0.47 in the radical polymerization4). Molecular weight information was obtained using a gel permeation chromatography calibrated with polystyrene standards. These copolymers were blended with PDOMA. The characteristics of these copolymers are also summerized in Table 1.

Table 1. Characteristics of Polymer Samples Used in this work

Sample	Mw	Mn	Mw/Mn	Tg(oC)
PGMA PDOMA MMA-EA(2wt%) MMA-EA(5wt%).	74,739 126,135 216,787 131,968	58,390 76,446 165,487 120,720	1.28 1.65 1.31 1.09	60.769 49.195 115.554 122.404

3) Blends of PDOMA with MMA-EA(2%,5%)

In Figures 2, however, PDOMA with MMA-EA(2,5wt%) blends are exhibited a single glass transition temperature(Tg) between the two Tgs of the components with broad transition region. The result indicates that these blends are miscible over the entire composition ranges. The solid lines in Figures 2 was drawn based on the Tg of blends by Fox equation, which neglected the enthalpy of mixing. It shows a composition dependence as follows5) ;

[eqn: {rm1} over {T_g } = { W_A} over {T_gA } + {W_B} over {T_gB }]

WA and WB are respectively the weight fractions of A and B components. The Fox equation fitted well with the experimental data within experimental errors. Of interest is, however, blend of PDOMA with MMA-EA(5wt%), the S-shaped curve for blends at high PDOMA composition. The result suggests that there be a specific interaction between PDOMA and the copolymer at high PDOMA composition.

Figure 2. Glass TransitionTemperatures of PDOMA/MMA-EA(2,5wt%)

Blends as a function of PDOMA Weight Fraction.

4.Reference

1. Moon, J. Y., Yang, J. G., Jung, S. M., Park, D. W. and Lee, J. K.,  React..Kinet. & Cat. Lett, 61(2), 315 (1997).

2. Nishikubo, T., Kameyama, A. and Sasano, M., J. Polym Science: Part A, 32, 301-308(1994)

3. Park, D. W., Moon, J. Y., Yang, J. G., Jung, S. M., Lee, J. K., Chang, C.S.,     Studies in Sur. sci. and Cata., 114, 403(1998).

4. Zou Yousi, Lin Donghai, Dai Lizhong, Zhang Jinghui and Pan Ronghua,        Polymer, 38(15), 3947(1997)

5. Woo, N. K., Charles, M. B., J. of Polymer science: Part B, 28,                  1409-14295(1998).