Aliphatic polycarbonate macropolyol and aliphatic polycarbonate-coaromatic polyester macropolyol

Abstract

Provided is an aliphatic polycarbonate macropolyol including OAO and Z(O).sub.a as repeating units. In the aliphatic polycarbonate macropolyol, the repeating units OAO and Z(O).sub.a are linked to each other via carbonyl (C(O)) linkers or are bonded to hydrogen to form terminal OH groups. The number of moles of the terminal OH groups is from aZ to aZ+0.2Z (where Z represents the number of moles of the repeating unit Z(O).sub.a). Further provided is an aliphatic polycarbonate-co-aromatic polyester macropolyol including OAO and Z(O).sub.a as repeating units. In the aliphatic polycarbonate-co-aromatic polyester macropolyol, the repeating units OAO and Z(O).sub.a are linked via carbonyl (C(O)) and C(O)YC(O) as linkers or are bonded to hydrogen to form terminal OH groups.

Claims

1. A method for producing an aliphatic polycarbonate macropolyol, comprising: (a) condensing HOAOH in the presence of a base catalyst and an agent comprising DMC to prepare a condensation product, wherein the condensation product is an aliphatic polycarbonate with a number average molecular weight of 10000 or higher, the condensing step comprising: (a1) reacting the HOAOH with the agent at ambient pressure at a first temperature to form oligomers, wherein, in the oligomers, OH and OCH.sub.3 are present in a ratio of about 1:1, and (a2) forming the condensation product from the oligomers at an elevated temperature higher than the first temperature and at a reduced pressure lower than ambient pressure; and (b) transesterifying the condensation product with Z(OH)a to form a final product, wherein the final product is an aliphatic polycarbonate with a number average molecular weight lower than that of the condensation product, wherein A is a substituted or unsubstituted C.sub.3-C.sub.60 alkylene or a combination of two or more substituted or unsubstituted C.sub.3-C.sub.60 alkylenes, wherein a is an integer from 2 to 4, provided that, when a is 2, Z is a substituted or unsubstituted C.sub.3-C.sub.60 alkanediyl, when a is 3, Z is a substituted or unsubstituted C.sub.3-C.sub.60 alkanetriyl, and when a is 4, Z is a substituted or unsubstituted C.sub.4-C.sub.60 alkanetetriyl, wherein the aliphatic polycarbonate macropolyol comprises: OAO and Z(O).sub.a as repeating units and a linker, the linker comprising carbonyl (C(O)), wherein the repeating units OAO and Z(O).sub.a are linked to each other via the linker or are bonded to hydrogen to form terminal OH groups, wherein the transesterifying step occurs in the presence of the base catalyst used in the condensing step, and wherein the number average molecular weight of the condensation product is at least 10 times higher than that of the final product.

2. The method according to claim 1, wherein the base catalyst is composed of a lithium, a sodium or potassium cation, and an alkoxy anion formed by deprotonation of the HOAOH, and wherein the base catalyst is used in an amount of 0.01 mol % to 0.1 mol %, based on the HOAOH.

3. The method according to claim 1, wherein the agent further comprises MeOC(O)YC(O)OMe, wherein Y is a substituted or unsubstituted C.sub.5-C.sub.20 arylene, a combination of two or more substituted or unsubstituted C.sub.5-C.sub.20 arylenes, a substituted or unsubstituted C.sub.5-C.sub.20 heteroarylene or a combination of two or more substituted or unsubstituted C.sub.5-C.sub.20 heteroarylenes.

4. The method according to claim 3, wherein the linker further comprises C(O)YC(O).

5. The method according to claim 1, wherein the step (a2) further comprising removing of methanol.

6. The method according to claim 1, wherein the unit Z(O).sub.a is present in an amount of 5 to 20 mol % with respect to the unit OAO.

7. The method according to claim 1, wherein, in the step (a), the HOAOH is a mixture of two or more different diol compounds containing the substituted or unsubstituted C.sub.3-C.sub.60 alkylenes.

8. The method according to claim 1, wherein, in the transesterifying step, the Z(OH).sub.a is provided in an amount of 5 to 20 mol % of the HOAOH.

9. The method according to claim 1, wherein the number average molecular weight of the condensation product is higher than 50000.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 compares (a) a traditional method for producing an aliphatic polycarbonate macrodiol with (b) a method for producing an aliphatic polycarbonate macrodiol according to the present invention.

(2) FIG. 2 shows the statistical distribution of chains of a macrodiol obtained using a diol as a chopping agent.

(3) FIG. 3 shows the statistical distribution of chains of a macrodiol obtained using a triol as a chopping agent.

BEST MODE FOR CARRYING OUT THE INVENTION

(4) The effects of the present invention will be explained in detail with reference to the following examples, including comparative examples. However, these examples are provided for illustrative purposes only and are not intended to limit the scope of the invention. Sodium was reacted with and dissolved in 1,4-butanediol, and then phthaloyl chloride was added thereto. The phthaloyl chloride was used in an amount of 0.25 equivalents per equivalent of the sodium. After stirring at 80 C. overnight, the mixture was distilled under a vacuum of 0.15 mmHg at 120 C. to obtain anhydrous 1,4-butanediol.

Examples 1-9: Condensation of Formula 1a (and Optionally Formula 1b or 1c) With DMC and Subsequent Chopping of the Condensation Product With One of Formulae 1b to 1h

(5) First step: 1,4-Butanediol (Formula 1a) and optionally 1,5-pentanediol (Formula 1b) or 1,6-hexanediol (Formula 1c) were placed in a 3-neck flask such that the total number of moles was 111 mmol. The 1,5-pentanediol or 1,6-hexanediol was used in the amount of 0 or 10 mol %, as shown in Table 1. NaH (0.056 mmol, 0.05 mol %) was added to the flask to form HO(CH.sub.2).sub.4O.sup.Na.sup.+ and then 15.7 g (174 mmol) of dimethyl carbonate (DMC) was added thereto. A mechanical stirrer was connected to one neck of the flask, a manifold attached with a vacuum line and a nitrogen line was connected to another neck of the flask, and a distillation unit was connected to the remaining neck of the flask. After the reaction flask was immersed in a thermostatic bath at 120 C., the reaction was carried out for 1 h while distilling off formed methanol and a portion of the DMC at ambient pressure. The reaction was continued for a total of 3.5 h while removing volatiles at an elevated temperature of 190 C. and a reduced pressure of 570 mmHg for 0.5 h, 380 mmHg for 1 h, and 190 mmHg for 2 h. Thereafter, the reaction was allowed to proceed at 190 C. for additional 2 h while removing volatiles under a high vacuum of 0.3 mmHg, which was maintained using a vacuum pump.

(6) Second step: A diol selected from Formulae 1b to 1h was used as a chopping agent. The chopping agent was added to the condensation product obtained in the first step. The chopping agent was used in an amount of 15 mol % (16.7 mmol), based on the diol(s) initially added. The reaction was carried out for 3 h while slowly cooling to 150 C. from 190 C. Within 10 min from the beginning of the reaction, a remarkable reduction in the viscosity of the reaction mixture was observed. As a result of the reaction, the condensation product was chopped with the chopping agent. The experimental results are summarized in Table 1.

(7) TABLE-US-00001 TABLE 1 <Experimental results obtained when condensation product of Formula 1a (and optionally Formula 1b or 1c) and DMC was chopped with one of Formulae 1b to 1h> Chopping agent, Yield.sup.a Before chopping- After chopping- T.sub.g State after State after 7 HOAOH Z(OH).sub.2 (15 mol %) (%) M.sub.n (M.sub.w/M.sub.n).sup.b M.sub.n (M.sub.w/M.sub.n).sup.b ( C.).sup.c 1 day days Example 1 1a 1b 81 90000 (1.71) 2400 (1.70) 12 Wax Wax Example 2 1a 1c 88 89000 (1.82) 2000 (1.70) 12 Wax Wax Example 3 1a 1d 88 40000 (1.56) 1800 (1.57) 48 Transparent Slight oil suspension Example 4 1a 1e 91 58000 (1.63) 2000 (1.56) 45 Transparent Wax oil Example 5 1a + 1b 1e 90 54000 (1.56) 1900 (1.60) 48 Transparent Transparent oil (90:10) oil Example 6 1a + 1c 1e 83 66000 (1.62) 1900 (1.60) 49 Transparent Transparent oil (90:10) oil Example 7 1a + 1c 1f 89 64000 (1.78) 2000 (1.62) 31 Wax Wax (90:10) Example 8 1a + 1c 1g 91 79000 (1.59) 2200 (1.65) 40 Orange oil Orange oil (90:10) Example 9 1a + 1c 1h 93 77000 (1.63) 2200 (1.60) 38 Transparent Transparent oil (90:10) oil .sup.aValue calculated from the actual mass of the obtained condensation product relative to the theoretical maximum mass of the condensation product. .sup.bValue measured on the basis of polystyrene standard in THF at 40 C. by GPC. .sup.cGlass transition temperature measured by DSC.

(8) The results in Table 1 demonstrate the production of aliphatic polycarbonate macrodiols and show that the molecular weights of the condensation products were reduced to at least 1/10, more preferably 1/20, by chopping, which is the feature of the present invention, and most of the macrodiols were obtained in the form of oils (some thereof were in the form of waxes). Particularly, the oily macrodiols were readily obtained when the diols of Formula 1a and Formula 1b or 1c were used in combination rather than when the diol of Formula 1a was used alone as the HOAOH.

Examples 10-21: Condensation of Formula 1a (and Optionally Formula 1c) With DMC and Subsequent Chopping of the Condensation Product With One of Formulae 2a to 2d

(9) The first step of Examples 1-9 was repeated.

(10) The second step of Examples 1-9 was repeated, except that a diol selected from Formulae 2a to 2d was used as a chopping agent. The experimental results are summarized in Table 2.

(11) TABLE-US-00002 TABLE 2 <Experimental results obtained when condensation product of Formula 1a (and optionally Formula 1c) and dimethyl carbonate was chopped with one of Formulae 2a to 2d> Chopping agent, Yield.sup.a Before chopping- After chopping- T.sub.g State after 1 State after 7 HOAOH Z(OH).sub.a (15 mol %) (%) M.sub.n (M.sub.w/M.sub.n).sup.b M.sub.n (M.sub.w/M.sub.n).sup.b ( C.).sup.c day days Example 10 1a 2a 81 69000 (1.62) 2200 (1.81) 49 Wax Wax Example 11 1a 2b 86 43200 (1.58) 2100 (1.96) 45 Wax Wax Example 12 1a 2c 85 49900 (1.54) 2000 (1.84) 57 Wax Wax Example 13 1a 2d 82 50000 (1.61) 1300 (1.71) 41 Wax Wax Example 14 1a + 1c 2a 81 53000 (1.43) 2100 (1.85) 50 Transparent Wax (95:5) oil Example 15 1a + 1c 2b 87 87000 (1.63) 2200 (1.87) 48 Transparent Suspended (95:5) oil oil Example 16 1a + 1c 2c 84 50000 (1.72) 1000 (1.31) 69 Yellow oil Yellow (95:5) Oil Example 17 1a + 1c 2d 89 39000 (1.58) 2500 (1.93) 44 Transparent Suspended (95:5) oil oil Example 18 1a + 1c 2a 93 65000 (1.62) 2300 (1.84) 58 Transparent Transparent (90:10) oil oil Example 19 1a + 1c 2b 85 50000 (1.53) 2400 (1.83) 51 Transparent Transparent (90:10) oil oil Example 20 1a + 1c 2c 82 21200 (1.59) 1800 (1.88) 62 Yellow oil Yellow (90:10) oil Example 21 1a + 1c 2d 73 50200 (1.73) 1800 (1.75) 48 Suspended Suspended (90:10) oil oil .sup.aValue calculated from the actual mass of the obtained condensation product relative to the theoretical maximum mass of the condensation product. .sup.bValue measured on the basis of polystyrene standard in THF at 40 C. by GPC. .sup.cGlass transition temperature measured by DSC.

(12) The results in Table 2 reveal that chopping of the high-molecular-weight aliphatic polycarbonates with the chopping agents of Formulae 2a to 2d led to the production of macropolyols with lower molecular weights. The polymers prepared in the first step before chopping were confirmed to have molecular weights at least 10 times (mostly at least 20 times) higher than those of the macropolyols produced after chopping, which is the feature of the present invention. The oily macropolyols were readily obtained when the diols of Formula 1a and Formula 1c were used in combination rather than when the diol of Formula 1a was used alone as the HOAOH.

Examples 22-35: Condensation of Formula 1a and One of Formulae 1b to 1h With DMC and Subsequent Chopping of the Condensation Product With Formula 2a

(13) First step: 1,4-Butanediol (Formula 1a) and an additional diol selected from Formulae 1b to 1h were placed in a 3-neck flask such that the total number of moles was 111 mmol. The additional diol was used in the amount of 5 mol % or 10 mol %, as shown in Table 1. NaH (0.056 mmol, 0.05 mol %) was added to the flask to form HO(CH.sub.2).sub.4O.sup.Na.sup.+ and then 15.7 g (174 mmol) of dimethyl carbonate (DMC) was added thereto. The subsequent procedure was carried out in the same manner as in Examples 1-9.

(14) Second step: The triol of Formula 2a as a chopping agent was added to the condensation product obtained in the first step. The chopping agent was used in an amount of 15 mol % (4.43 g, 16.7 mmol), based on the diols initially added. The reaction was carried out for 3 h while slowly cooling to 150 C. from 190 C. Within 10 min from the beginning of the reaction, a remarkable reduction in the viscosity of the reaction mixture was observed. As a result of the reaction, the condensation product was chopped with the chopping agent. The experimental results are summarized in Table 3.

(15) TABLE-US-00003 TABLE 3 <Experimental results obtained when condensation product of Formulae 1a, one of Formulae 1b to 1h, and dimethyl carbonate was chopped with Formula 2a> Chopping agent, Yield.sup.a Before chopping- After chopping- T.sub.g State after 1 State after 7 HOAOH Z(OH).sub.a (15 mol %) (%) M.sub.n (M.sub.w/M.sub.n).sup.b M.sub.n (M.sub.w/M.sub.n).sup.b ( C.).sup.c day days Example 22 1a + 1b 2a 85 64000 (1.55) 2000 44 Suspended Suspended (95:5) (1.74) oil oil Example 23 1a + 1d 2a 85 35000 (1.72) 2000 42 Slight Slight (95:5) (1.86) suspension suspension Example 24 1a + 1e 2a 83 38000 (1.58) 2000 46 Suspended Slight (95:5) (1.71) oil suspension Example 25 1a + 1f 2a 82 48000 (1.64) 2000 40 Slight Slight (95:5) (1.81) suspension suspension Example 26 1a + 1g 2a 83 45000 (1.56) 2100 41 Slight Slight (95:5) (1.86) suspension suspension Example 27 1a + 1h 2a 96 43000 (1.57) 1900 48 Transparent Transparent (95:5) (1.83) oil oil Example 28 1a + 1b 2a 85 85000 (1.45) 2000 46 Transparent Transparent (90:10) (1.79) oil oil Example 29 1a + 1d 2a 82 45000 (1.61) 2200 43 Transparent Transparent (90:10) (1.84) oil oil Example 30 1a + 1e 2a 85 51000 (1.51) 2000 38 Transparent Transparent (90:10) (1.75) oil oil Example 31 1a + 1f 2a 91 58000 (1.61) 2100 32 Transparent Transparent (90:10) (1.82) oil oil Example 32 1a + 1g 2a 82 44000 (1.56) 1900 36 Slight Slight (90:10) (1.80) suspension suspension Example 33 1a + 1h 2a 87 81000 (1.77) 2100 40 Transparent Transparent (90:10) (1.94) oil oil Example 34 1a + 1b 2a 87 60000 (1.40) 4500 46 Wax Wax (90:10) (5 mol %) (1.83) Example 35 1a + 1b 2a 85 87000 (1.50) 3200 43 Wax Wax (90:10) (10 mol %) (1.58) .sup.aValue calculated from the actual mass of the obtained condensation product relative to the theoretical maximum mass of the condensation product. .sup.bValue measured on the basis of polystyrene standard in THF at 40 C. by GPC. .sup.cGlass transition temperature measured by DSC.

(16) The results in Table 3 show that most of the macropolyols produced by chopping the high-molecular-weight aliphatic polycarbonates, which were prepared using 1,4-butanediol as a major raw material, with Formula 2a as a chopping agent were in the form of oils. All polymers prepared in the first step before chopping were confirmed to have molecular weights at least 10 times (mostly at least 20 times) higher than those of the macropolyols produced after chopping.

Examples 36-39: Condensation of Formula 1a, DMC, and MeOC(O)YC(O)OMe and Subsequent Chopping of the Condensation Product With Formula 1a or 1d

(17) First step: 1,4-Butanediol (Formula 1a, 10.0 g, 111 mmol) was placed in a 3-neck flask and then NaH (0.111 mmol, 0.1 mol %) was added thereto to form HO(CH.sub.2).sub.4O.sup.Na.sup.+. Thereafter, dimethyl carbonate (DMC) and dimethyl phthalate (or dimethyl isophthalate or dimethyl terephthalate) were added in the amounts shown in Table 4. The DMC was added in an amount corresponding to the number of moles calculated by subtracting the number of moles of the phthalate from the number of moles corresponding to 1.57 equivalents per equivalent of the 1,4-butanediol. A mechanical stirrer was connected to one neck of the flask, a manifold attached with a vacuum line and a nitrogen line was connected to another neck of the flask, and a distillation unit was connected to the remaining neck of the flask. After the reaction flask was immersed in a thermostatic bath at 120 C., the reaction was carried out for 1 h while distilling off formed methanol and a portion of the DMC at ambient pressure. The reaction was continued for a total of 3.5 h while removing volatiles at an elevated temperature of 190 C. and a reduced pressure of 570 mmHg for 0.5 h, 380 mmHg for 1 h, and 190 mmHg for 2 h. Thereafter, the reaction was allowed to proceed further at an elevated temperature of 210 C. for additional 2 h while removing volatiles under a high vacuum of 0.3 mmHg, which was maintained using a vacuum pump.

(18) Second step: 1,4-Butanediol (Formula 1a) as a chopping agent was added to the condensation product obtained in the first step. The chopping agent was used in an amount of 15 mol % (1.50 g, 16.7 mmol), based on the diol initially added. The reaction was carried out for 3 h while slowly cooling to 150 C. from 210 C. Within 10 min from the beginning of the reaction, a remarkable reduction in the viscosity of the reaction mixture was observed. As a result of the reaction, the condensation product was chopped with the chopping agent. The experimental results are summarized in Table 4.

(19) TABLE-US-00004 TABLE 4 <Experimental results obtained when condensation product of Formula 1a, DMC, and MeOC(O)YC(O)OMe was chopped with with Formula 1a or 1d (15 mol %)> C(O)YC(O) Chopping Yield Before chopping- After chopping- T.sub.g State after 1 State after 7 (mol % per 1a) agent, Z(OH).sub.2 (%).sup.a M.sub.n (M.sub.w/M.sub.n).sup.b M.sub.n (M.sub.w/M.sub.n).sup.b ( C.).sup.c day days Example 36 Terephthalate 1a 89 80900 2700 42 Wax Wax (30 mol %) (1.57) (1.62) Example 37 Isophthalate 1a 89 69700 2500 36 Slightly Suspended (30 mol %) (1.50) (1.60) suspended oil oil Example 38 Phthalate 1a 91 58600 2300 43 Slightly Slightly (30 mol %) (1.52) (2.1) suspended oil suspended oil Example 39 Phthalate 1d 89 83600 3300 27 Slightly Slightly (30 mol %) (1.57) (1.70) suspended oil suspended oil .sup.aValue calculated from the actual mass of the obtained condensation product relative to the theoretical maximum mass of the condensation product. .sup.bValue measured on the basis of polystyrene standard in THF at 40 C. by GPC. .sup.cGlass transition temperature measured by DSC.

(20) The results in Table 4 show that aliphatic polycarbonate-co-aromatic polyester macrodiols having new structures according to claims 8-10 were readily produced by chopping, which is the feature of the present invention. Particularly, the presence of the isophthalate or phthalate repeating units was confirmed to increase the possibility that the macrodiols might be produced in the form of oils.

Examples 40-60: Condensation of Formula 1a, DMC and MeOC(O)YC(O)OMe and Subsequent Chopping of the Condensation Product With One of Formulae 2a to 2d

(21) The first step of Examples 36-39 was repeated, except that the amount of dimethyl phthalate (or dimethyl isophthalate or dimethyl terephthalate) added was adjusted to the range of 10 to 50 mol %. When the phthalate was used in an amount not larger than 20 mol %, volatiles were finally removed under a high vacuum of 0.3 mmHg at 190 C. instead of at 210 C.

(22) The second step of Examples 36-39 was repeated, except that a diol selected from Formulae 2a to 2d was used as a chopping agent. The experimental results are summarized in Table 5.

(23) TABLE-US-00005 TABLE 5 <Experimental results obtained when condensation product of Formula 1a, DMC, and MeOC(O)YC(O)OMe was chopped with one of Formulae 2a to 2d (15 mol %)> C(O)YC(O) Chopping Yield Before chopping- After chopping- T.sub.g State after 1 State after 7 (mol % per 1a) agent, Z(OH).sub.a (%).sup.a M.sub.n (M.sub.w/M.sub.n).sup.b M.sub.n (M.sub.w/M.sub.n).sup.b ( C.).sup.c day days Example 40 Isophthalate 2a 88 72000 2400 43 Transparent Transparent (10 mol %) (1.42) (1.83) oil oil Example 41 Isophthalate 2a 87 78000 2600 38 Transparent Transparent (20 mol %) (1.56) (1.85) oil oil Example 42 Isophthalate 2a 87 68000 2600 35 Transparent Transparent (30 mol %) (1.50) (1.82) oil oil Example 43 Isophthalate 2a 90 82600 2400 29 Slight Suspended (40 mol %) (1.58) (1.95) suspension Oil Example 44 Isophthalate 2a 91 75200 2700 28 Wax Wax (50 mol %) (1.56) (1.83) Example 45 Isophthalate 2b 89 107200 2300 28 Transparent Transparent (30 mol %) (1.47) (1.73) oil oil Example 46 Isophthalate 2c 86 80900 1900 44 Brown oil Brown oil (30 mol %) (1.50) (1.65) Example 47 Isophthalate 2d 88 94400 2400 24 Transparent Transparent (30 mol %) (1.39) (1.84) oil oil Example 48 Terephthalate 2a 90 72900 2400 44 Suspended Suspended (10 mol %) (1.38) (1.83) oil oil Example 49 Terephthalate 2a 89 73500 2600 39 Wax Wax (20 mol %) (1.39) (1.88) Example 50 Terephthalate 2a 91 118100 2800 35 Wax Wax (30 mol %) (1.41) (1.97) Example 51 Terephthalate 2a 85 80800 2800 33 Wax Wax (40 mol %) (1.49) (1.91) Example 52 Terephthalate 2a 87 78600 2900 33 Wax Wax (50 mol %) (1.44) (1.87) Example 53 Terephthalate 2b 90 81700 3000 28 Wax Wax (30 mol %) (1.53) (2.10) Example 54 Terephthalate 2c 89 102700 1800 49 Brown wax Brown wax (30 mol %) (1.63) (1.70) Example 55 Terephthalate 2d 90 82500 2100 25 Wax Wax (30 mol %) (1.44) (1.63) Example 56 Phthalate 2a 87 83000 2200 41 Transparent Transparent (10 mol %) (1.61) (1.74) oil oil Example 57 Phthalate 2a 87 47800 2300 36 Transparent Transparent (20 mol %) (1.60) (1.71) oil oil Example 58 Phthalate 2a 89 62300 2500 27 Transparent Transparent (30 mol %) (1.49) (1.62) oil oil Example 59 Phthalate 2b 85 71100 2400 29 Transparent Transparent (30 mol %) (1.56) (1.74) oil oil Example 60 Phthalate 2d 88 76400 1900 24 Transparent Transparent (30 mol %) (1.63) (1.51) oil oil .sup.aValue calculated from the actual mass of the obtained condensation product relative to the theoretical maximum mass of the condensation product. .sup.bValue measured on the basis of polystyrene standard in THF at 40 C. by GPC. .sup.cGlass transition temperature measured by DSC.

(24) The results in Table 5 show the production of aliphatic polycarbonate-co-aromatic polyester macrodiols with various compositions. Particularly, the presence of the isophthalate or phthalate repeating unit was confirmed to increase the possibility that the macrodiols might be produced in the form of oils.

Comparative Example 1: Attempt to Directly Produce Low-Molecular-Weight Diol by Condensation of Formula 1a With DMC

(25) 1,4-Butanediol (Formula 1a, 10.0 g, 111 mmol) and NaH (0.222 mmol, 0.2 mol %) were placed in a 3-neck flask to form HO(CH.sub.2).sub.4O.sup.Na.sup.+. Thereafter, 15.3 g (170 mmol) of dimethyl carbonate (DMC) was further added. The DMC was used in a small amount compared to the amounts used in the previous examples to synthesize oligomers whose molecular weights are on the order of several thousands and whose ends are all capped with OH. A mechanical stirrer was connected to one neck of the flask, a manifold attached with a vacuum line and a nitrogen line was connected to another neck of the flask, and a distillation unit was connected to the remaining neck of the flask. After the reaction flask was immersed in a thermostatic bath at 120 C., the reaction was carried out for 1 h while distilling off formed methanol and a portion of the DMC at ambient pressure. The reaction was carried out at ambient pressure and an elevated temperature of 180 C. for another 1 h until the amount of distilled volatiles (methanol or DMC) reached a negligible level. After a 1 h reaction under a reduced pressure of 380 mmHg, the reaction mixture was sampled for .sup.1H NMR analysis. As a result, the integral values corresponding to CH.sub.2OC(O), OCH.sub.3, and OH were 10.1, 0.71, and 1.0, respectively. After the reaction was continued at the same pressure for additional 1 h, the integral values were changed to 11.5, 0.63, and 1.0, respectively. These results indicate that the reaction rate was very low. For more effective removal of byproducts, the reaction was allowed to proceed further under a high vacuum of 0.3 mmHg for 2 h. .sup.1H NMR analysis revealed that the peaks corresponding to OCH.sub.3 groups disappeared completely and the final polymer was end-capped with OH only. The polymer had a molecular weight (M.sub.n) of 20000, which was higher than that expected. During the reaction under a reduced pressure of 380 mmHg, the ambient OH groups were hydrogen-bonded with the alkoxy anions to weaken the nucleophilic attack of the alkoxy anions and were also hydrogen-bonded with the formed methanol to impede effective removal of the methanol. This hydrogen bonding is interpreted to be responsible for the low rate of the reaction. When the pressure was further reduced to 0.3 mmHg, the butanediol, DMC, and HO(CH.sub.2).sub.4OC(O)OCH.sub.3 as well as methanol were removed, and as a result, the chains were connected to each other, leading to a rapid increase in molecular weight. Therefore, the molecular weight of the polymer was confirmed to be difficult to control.

Comparative Example 2: Chopping of Low-Molecular-Weight Condensation Product With Formula 2a

(26) 10 mol % of 1,4-butanediol (Formula 1a) and the diol of Formula 1e were placed in a 3-neck flask such that the total number of moles was 111 mmol. NaH (0.056 mmol, 0.05 mol %) was added to the flask to form HO(CH.sub.2).sub.4O.sup.Na.sup.+ and then 14.5 g (161 mmol) of dimethyl carbonate (DMC) was added thereto. The subsequent procedure was carried out in the same manner as in Examples 22-35. In the first step, a polymer with a number average molecular weight of 5000 was obtained. Chopping of the polymer afforded a macropolyol with a number average molecular weight of 1900. The molecular weight of the polymer before chopping was on the order of about 2.5-fold higher than that of the macropolyol after chopping. The presence of a relatively large number of highly crystalline linear chains free of Z(O).sub.3 in the macropolyol made the macropolyol waxy. The shape of the macropolyol was compared with that of a macropolyol having a number average molecular weight (Mn) at the same level. For example, the macropolyol of Example 30 (Mn=2000), which was produced by chopping the high-molecular-weight polymer (Mn=51000) prepared using the same composition in the first step with the same chopping agent (Formula 2a), was in the form of a transparent oil suitable for use in polyurethane and lubricating agents.