NZ502021A - Heterotelechelic block copolymer and a polymeric micelle comprising the heterotelechelic block copolymer in an aqueous solvent - Google Patents

Abstract

The heterotelechelic block copolymer has the formula (I), wherein: R1 and R2 independently denote C1-10 alkoxy or phenyl-C1-3 alkyloxy, or R1 and R2 combined with each other, denote an ethylenedioxy (-O-CH(R')-CH2-O-: wherein R' denotes H or C1-6 alkyl) which may be substituted with C1-6 alkyl, or, combined with each other, denote oxy (= O). L is a moiety of formula (II) or (III), wherein R3 and R4 independently denote H or C1-10 alkyl, and r denotes an integer of 2-5. m is an integer of 2 - 10 000 n is an integer of 2 - 10 000 p is an integer of 1 - 5 q is an integer of 0 - 20 Z denotes, when q is zero, H, alkali metal, acetyl, acryloyl, methacryloyl, cinnamoyl, p-toluenesulfonyl, 2-mercaptopropionyl or 2-aminopropionyl, or allyl or vinylbenzyl, while, when q is an integer of 1-20, denoting C1-6 alkoxycarbonyl, carboxymercapto or amino.

Description

PATENTS FORM 5 Number PATENTS ACT 1953 Dated COMPLETE SPECIFICATION Divided out of application no. 305471 filed 18 April 1996 HETEROTELECHELIC BLOCK COPOLYMER AND A METHOD FOR THE PRODUCTION THEREOF I, KAZUNORI KATAOKA, a Japanese citizen of 1083-4, Ohmuro, Kashiwa-shi, Chiba 277, Japan, do hereby declare the invention for which I pray that a patent maybe granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement. ~ (followed by la) L L.

J 157499 vl WGN * (H ^ 0 ^ <w 1a DESCRIPTION INTELLEaUAL PROPERTY OFFICE OF N.Z. 1 o JUL 2001 RECEIVED HETEROTELECHELIC BLOCK COPOLYMER AND A METHOD FOR THE PRODUCTION THEREOF Field of the invention The present invention relates to a hetero-telechelic block copolymer which has different functional groups on its both ends, a method for the production 10 thereof and its application to high-molecular micelle. More detailedly, this invention discloses a polymer which has different functional groups on its both ends while having, in its main chain, polyethylene oxide as a hydrophilic segment and polyester as a hydrophobic 15 s egment.

In this invention, the term "polymer" includes oligomer. Also, as used herein, the term "high-molecular micelle" can be understood to mean "polymeric micelle" or macromolecular micelle".

Prior arts A high-molecular micelle or nanosphere com posed of a hydrophi1ic/hydrophobic type block copolymer wherein a hydrophilic polymer like polyethylene oxide is combined with a hydrophobic polymer at the molecular level is now attracting attention as a carrier for drug 25 delivery or the like. Said high-molecular micelle and nanosphere have been prepared from a hydrophi1ic/hydrophobic type block copolymer wherein a hydrophilic polymer is combined with a hydrophobic polymer at the molecular level.

In conventional processes to produce a hydro phi 1ic/hydrophobic type block copolymer, however, there is a limitation on the species of terminal functional groups introduced, and there have only been proposed block copolymers whose functional groups are restricted 35 to methoxy and hydroxyl groups. If one succeeded in introducing optional functional groups onto the micelle INTELLECTUAL PROPERTY OFFICE OF N.Z. 1 0 JUL 2001 received surface at an optional proportion, it would become possible to provide a functional high-molecular micelle which could be useful for drug delivery to certain o rgans.

The object of this invention is to provide a block copolymer, which has different functional groups on its both ends, as a polyfunctional polymer which is capable of forming a high-molecu!ar micelle.

Disclosure of invention The inventors of this invention have found out that there can easily be produced a block copolymer which has a protected or non-protected aldehyde group on one end of molecule and various functional groups on the 15 other end, when an alkylene derivative having a certain kind of aldehyde group and a hydroxyl group is utilized as a living polymerization initiator and when ethylene oxide and lactide or lactone are polymerized as monomers.

They have also confirmed that a block copoly mer obtained in this manner forms a high-molecular micelle which is quite stable in an aqueous solvent.

This invention provides a heterotelechelic block copolymer which has different functional groups on 25 both ends of molecule and which is represented by formula (I) be!ow: R1 )cH-fCH2)-(HCH2CH20)—(C-L-0)—(CH2>— Z ,, ^ R2 P mn n ^ 0 1 2 wherein R and R independently denote ^ alkoxy or phenyl-C1_3 alkyloxy, or R1 2 and R , combined with each other, denote 35 ethylenedioxy (-0-CH(R')-CHj-0-: wherein R1 denotes hydrogen atom or _ g al kyl ) which may K f) ° ^ "1 Ml i. I // ^ f - V k=l INTELLECTUAL PROPERTY OFFICE OF N.Z. 1 0 JUL 2001 RECEIVED be substituted with Cj _ g alkyl, or, combined with each other, denote oxy (= 0), L denotes — R3 CH-0 R4 C — C H — ° r —k C H 2^— II r O 3 4 wherein R and R independently denote a hydrogen atom or C1_10 alkyl, and r denotes an integer of 2 - 5, m denotes an integer of 2 - 10,000, n denotes an integer of 2 - 10,000, p denotes an integer of 1 - 5, q denotes an integer of 0 - 20, Z denotes, when q is 0 (zero), hydrogen atom, alkali metal, acetyl, acryloyl, methacryloy1, cinnamoyl, p-to1uenesulfony1 , 2-mercaptopropionyl or 2-aminopropionyl , or al 1 yl or vinyl benzyl, while, when q is an integer of 1 - 20, denoting Cj_g al koxycarbonyl, carboxy1, mercapto or amino.

As another aspect, this invention provides a process to produce the block copolymer of the above formula (I) which process comprises the following steps: Step (1 ) A polymerization initiator represented by the following formula (II) Ri-i )CH-(CH2)-0-M+ (") R2"1 P 1-1 2-1 wherein R and R independently 4 1-1 2-1 denote Cj _ 1 alkoxy, or, R and R combined with each other, denote ethy1enedioxy which may be substituted with Cj g alkyl , p denotes an integer of 1-5 and M denotes alkali metal is made to react with ethyleneoxide so that a compound represented by the following formula (III) may be pro-d uced: E'"' - .-..+ )cH-eCH2)"(HCH2CH20) CH2CH20 M (HI) -v p m-1 R2 1-1 2-1 wherein R , R , p and M are as de-15 fined in formula (II), and m denotes an integer of 2 - 10,000.

Step (2) The compound of formula (II) is allowed to 20 react with lactide or lactone which is represented by the following formula (Ill-a) or (Ill-b): o r *-/>« (HI-a) 0=a £H—R4 0 \ch2)^ (Ill-b) 3 4 wherein R and R independently denote -hydrogen atom, Q alkyl, aryl or ~ aryl-C^ j alkyl, and r denotes an integer 35 of 2 - 5, so that a block copolymer represented by the following formula (IV) may be formed: Rl-l )CH-(CH2)-(HCH2CH20>—(C—L—0>— C-fc-0 M+ -r p m II n-1 H (IV) E2 - - - o — o wherei n R3 R4 L denotes -CH-'O-C-CH- or -4CH2)- II r O 1-1 2-1 and R , R , p, m, n and M are as defi ned above.

The above step provides a living polymer of this invention (which is included in the polymer of formula (I)) which is usable as an intermediate for further extending some polymer segment or other.

Step (3) (i) The alkali metal al koxide of formula (IV) is selectively hydrolyzed to form a block copolymer of the following formula (V) Ri-i ^CH-fCH2)~0-(CH2CH203—(C—L—0)—H (V) R2-i p m N n 1-1 2-1 wherein R , R , p, m, L and n are as 30 defined above; or (ii) the block copolymer of formula (IV) is com- -pletely hydrolyzed to form a block copolymer of the following formula (VI) °\ /CH-fCH2)-(HCH2CH20)—(C-L-O)—H <VI) H P m M n wherein p, m, n and L are as defined abov e.

The above steps provide a block copolymer of this invention which has a protected aldehyde group or 10 an aldehyde group itself at the a-terminal of molecule, and a hydroxy! group at the (o-terminal.

Step (4) The block copolymer of formula (V) which has a 15 protected aldehyde group at the a-terminal of molecule is allowed to react with (i) acetic acid, acrylic acid, methacrylic acid, cinnamic acid or p-toluenesulfonic acid, or a reactive derivative thereof, or 20 (ii) al1yl halide or vinylbenzyl halide, or (iii) a halide represented by the following formula (VII) X-f CH2)—Z' (VII) <l' wherein X is chlorine, bromine or iodine, q1 is an integer of 1 - 20 and Z1 is C1 _B alkoxycarbonyl or a protected ami n o, to form block copolymers of this invention each of whrrch has a corresponding functional group other than hydrox-yl group at the u-terminal of molecule. ~ Step (5) The p-to!uenesulfonic ester obtained in (i) of 7 Step (4) can be further converted, by means of transesterification, into a block copolymer having another functional group (e.x., mercapto or amine) at the (j-termi nal . The block copolymer which has an 5 aldehyde-protecting group or a carboxyl-protecting group and which has been produced through the above steps can be converted, by means of hydrolysis reaction, into the block copolymer of this invention wherein one of the protecting groups or all the protecting groups are 10 e1i mi na ted.

As another aspect, this invention provides a hi gh-fnol ecu! a r micelle with use of the block copolymer of formula (I).

A part of thus obtained heterotelechelic 15 polymer of this invention can be used as a precursor for the production of another polymer. As will be seen from their constituent components, these polymers are expected to have bio-affinity and high bioavailability. They can therefore be used for materials directly applied to 20 living organism such as carrier for drug delivery. Moreover, in accordance with the third aspect, this invention provides a high-molecular micelle which is quite stable in an aqueous solvent. The polymer of this invention is therefore useful also for drug delivery to 25 a certain organ.

Brief explanation of drawings Figure 1 is a gel permeation chromatogram of acetal a-terminal/hydroxy a-terminal polyester ox-30 ide/pol ylactide block copolymer (the sample of Example 1 )• Operational condition: TSK-Gel (G4000HXL, G3000HXL, G2500HXL) ~ Eluent: THF (containing 2 % triethyl amine) 35 Flow rate: 1 ml/min. 8 Figure 2 shows proton nuclear magnetic resonance spectra of acetal a-termi nal/hydroxy a-terminal polyethylene oxide/polyl actide block copolymer (the sample of Example 1).

Figure 3 shows proton nuclear magnetic resonance spectra of acetal a-terminal/hydroxy a-terminal polyethylene oxide/poly(5-valerolactone) block copolymer (the sample of Example 3).

Figure 4 shows proton nuclear magnetic resonance spectra of aldehyde a-termi nal / hydroxy a-terminal polyethylene oxide/polylactide block copolymer (the sample of Example 4).

Figure 5 shows carbon nuclear magnetic resonance spectra of acetal a-termi nal/methacryloyl co-terminal polyethylene oxide/polylactide block copolymer (the sample of Example 5).

Figure 6 shows carbon nuclear magnetic resonance spectra of acetal a-termi nal/al 1 yl a- terminal polyethylene oxide/polyl actide block copolymer (the sample of Example 6).

Figure 7 shows carbon nuclear magnetic resonance spectra of acetal a-terminal/p-toluenesulfonyl a~ terminal polyethylene oxide/polylactide block copolymer (the sample of Example 6).

Figure 8 shows the particle size di st ri bu ti-en of high molecular micelle, determined by dynamic laser-scattering, in an aqueous solution of aldehyde a-termi^ nal/hydroxy a-terminal polyethylene oxide/polylactide block copolymer (the sample of Example 4). 9 Detailed description of the invention The alkyl portion of alkoxy and alkyl in this invention mean straight chain- or branched-alkyl group. Therefore, the alkyl portion of Cj_^g alkoxy or 5 alkyl in formula (II) and formula (Ill-a) include methyl, ethyl, propyl, iso-propyl, butyl, sec-butyl, tert-butyl, pentyl , iso-pentyl, hexyl , 2-methyl pentyl, 3-methyl pentyl, octyl, 2-ethylhexyl, decyl and 4-propyl pentyl. In these, the alkyl portion in the alkoxy of 2 and R is preferably _ g alkyl, in particular Cj _ ^ a 1kyl.

Especially preferable examples of alkoxy of_R* 2 and R therefore include methoxy, ethoxy, propoxy and - 1 2 isopropoxy. Examples of R and R include aryl, espe- cially phenyl, and aryl-C^j alkyl, especially benzyl or phenethyl. These groups may be similar or different, 1 2 but is preferably similar. Although R and R may denote, combined with each other, ethylenedioxy (-0-CH(R')-CHg-0-: wherein R1 denotes hydrogen atom or 20 alkyl) which may be substituted with Cj g alkyl, they are preferably ethylenedioxy, propylenedioxy or 1, 2-butylenedioxy. 1 2 When hydrolyzed, R and R of these groups are conveniently combined with each other to form oxy (= 0), 25 or, in other words, to form the block copolymer of this invention which has an aldehyde group at the a-terminal of the molecule.

The mark "p" in formula (I) denotes an integer of 1 - 5. In view of the fact that the segment R\ ;cH-ecH2>— o— R2 p is derived from the polymerization initiator (See: formula (II)) in the process of this invention, R^ and p are preferably selected so that said segment constitutes en bloc an acetal group such as dimethoxy-methoxy, 2, 2-dimethoxyethoxy, 3, 3-dimethoxypropoxy, 4, 4-dimethoxybutoxy, diethoxymethoxy , 2, 2-diethoxy-ethoxy, 3, 3-diethoxypropoxy, 4, 4-diethoxybutoxy, 5 dipropoxymethoxy, 2, 2-dipropoxyethoxy, 3, 3-dipropoxy- propoxy or 4, 4-dipropoxybutoxy . 3 4 R and R may denote any of hydrogen atom, Cj i q alkyl, aryl or aryl-C^ j alkyl so long as they are useful for the object of this invention. Preferable, 10 however, are hydrogen atom (derived from glutaric acid) and methyl (derived from lactic acid) from the viewpoint of bioavailability.

According to the production process by means, of living polymerization of this invention, the mark "m" 15 in formula (I) may theoretically take any figure if the amount ratio of ethylene oxide (monomer) to polymerization initiator is adjusted. In order to fulfill the object of this invention, however, m is preferably an integer of 2 - 10,000. In order that this segment may 20 give hydrophi1icity to the block copolymer of this invention, m is preferably an integer at least 10. For the purpose of easily adjusting the molecular weight distribution of this segment narrow and providing a block copolymer having excellent bioavailability, m is 25 an integer of at most 500, preferably at most 200.

As for "n" which defines the molecular weight of polyester segment of formula (I), optimal number 3 4 varies depending on the property of the groups R and R as will be seen from the fact that this segment mainly 30 imparts hydrophobicity to the block copolymer of this invention. Following the polymerization process of th-i s invention, n can take any number in the same manner as-m the'case of polyethylene oxide segment. The number" of n is therefore not restricted. However, it is nor-35 mally 2 - 10,000. 7 Moreover, in order to keep hydrophi1icity/ 11 hydrophobicity balance well against polyethylene oxide segment, m preferably takes an integer of 10 - 200, in particular 10 - 100.

The segment —Z of formula (I) mainly 5 specifies the functional group (or reactive group) at to-terminal of the block copolymer of this invention. When q is 0 (zero) (i.e., the case where Z is directly bound to oxygen atom at the w-position of the polyester segment), Z can be an alkali metal . In this case, the 10 polymer of this invention can be a living polymer.

Since such a polymer of this invention can act as an initiator for further living polymerization, it is useful as a precursor for various kind of polymers.

From this viewpoint, examples of alkali metal include 15 sodium, potassium and cesium.

The above living polymer is ready to provide a polymer wherein Z denotes hydrogen atom (or a polymer which has hyd roxyl group at the <j-posi tion) since the alcohol ate portion of the living polymer is easily 20 hydrolyzed. Said hydroxyl group can further be converted into other functional groups by means of various reactions such as esterification or etherification.

Thus, when q is 0, Z can be acetyl (-COCHg ) , acryloyl (-COCI-^CH;), methacryloyl (-C0C(CHj)=CH2), cinnamoyl 25 (~CHCH=CH <Q) ) and p- tol uenesu 1 f onyl (-SO; ) » and, further, can be allyl (-CHg -ChNCH; ) and vinylbenzyl (-CHg (q)-CH=CH2 ) . When these functional groups have ethylenical1y unsaturated bond, pendant type polymers can be derived with use of said bond. When Z denotes 30 p-toluenesulfonyl group, it can be converted by a known method into other functional group with use of trans— esterification . Z can therefore be 2-mercaptopropionyl or 2-aminopropiony1 . ~ When q is an integer of 1 - 20, preferably 1 -35 4, especially preferably 2, the segme n t Z denotes 7 en bloc, for example, Cj_j alkoxy (e.x., methoxy, ethoxy 12 or propoxy)carbonyl-methy1, -ethyl or -propyl, or 2-aminoethyl, carboxy-methyl, -ethyl or -propyl.

Table 1 below shows examples of block copolymer of this invention which the above substituents (or 5 segments) are combined with one another to constitute. 13 Table 1 R1 )aKCH2)-0-fCH2CH20)—(C-L-O)—(CH2>—Z ( I ) R1 P m » n q Compound ri R2 p m*i> L n*2> -(CH2)-Z No q CH3 ch3 1 CH3CH20 CH3CH2O 2 280 -iHOciH- 40 H 0 CH3 ch3 2 CH3CH2O CH3CH2O 2 280 -ilttciH- 40 K II 0 CH3 ch3 3 CH3CH20 CH3CH2O 2 280 -iHOciH- 70 H II 0 CH3 ch3 4 CH3CH2O CH3CH2O 2 280 -iHOciH- 70 K 0 CH3 ch3 CH3CHz0 CH3CH20 2 280 -iHOC^H- 70 C0CH=CH2 0 CH3 Cfl3 6 CH3CH2O CH3CH2O 2 280 -iHOciH- 70 C0C(CH3) = CH2 0 CH3 ch3 7 CH3CH20 CH3CH20 2 280 -iHOciH- 70 CH2<^)-^ 0 CH3 CH3 8 CH3CH20 CH3CH2O 2 280 -AHOCAH- 70 S02<^)-CH3 0 14 Table 1 (continued) Compound Ri R* p m*1' L n*2) -*CH2)-Z No q CH3 CH3 9 CH3CH2O CHsCH20 2 280 -AHOCAH- 70 CO-CHSH 0 CH3 ch3 CH3 CH3CH20 CH3CH20 2 280 -AHOCAH- 70 C0CHNH2 0 CH3 ch3 ch3 11 CH3CH20 CH3CH20 2 280 -AHOCAH- 70 C0CH3 0 CH3 ch3 12 CH3CH20 CH3CH20 3 100 -AHOCAH- 70 H 0 CH3 CH3 13 CHgO CH3O 2 100 -AHOCAH- 70 H 0 14 CH3CH20 CH3CH20 2 100 ~(CH2^t 50 H CH3CH20 CH3CH20 2 100 -6CH2}t 50 K 16 CHsCH20 CH3CH20 2 100 —6CH2^t 50 C0CH=CH2 17 CH3CH20 CHsCH20 2 100 ~(CH2^-3- 50 C0C(CH3)=CH^ ch3 ch3 18 0= 2 280 -AHOCAH- 40 H 0 ch3 ch3 19 0= 2 100 -AHOCAH- 70 H Table 1 (continued) Compound Ri R2 p m*n L n*2> _{CH2}-Z No q 0= 2 100 ch3 ch3 -ihocih- II 0 70 coch=ch2 21 0= 2 100 ch3 ch3 -ihocih- II 0 70 c0c(ch3)=ch2 22 0 = 2 100 ch3 ch3 -ihocih- ii 70 ch2(o)—^ 0 23 0 = 2 100 ch3 ch3 -ihocih- II 0 70 coch3 24 0= 3 100 ch3 ch3 -ihocih- II 0 70 H - 0= 2 100 -£ch2)t 50 h 26 0= 2 100 H:CH2:br 50 coch=ch2 27 0 = 2 100 ~£ch2}t 50 c0c(ch3)=ch2 *1) and 2) show values calculated from number average molecular weight. _ The above-mentioned heterotelechelic block — copolymer which is to be provided by this invention is 35 produced efficiently by the production process of this invention which is shown by the following reaction 16 s chemes .

Reaction Scheme ch2—ch2 R1 \)/ )ch-^ch2>-o-m+ ^ R2 P (A) R1 )CIKCH2)-(HCH2CH20) CH2CH20 M g2x p m-1 (B) R3v ,0 or l 0 CT NR4 (CH2)/ r \ Rl\ " + XH-^CH2)-0-fCH2CH20)—(C-L-0) C—fc—0 M R2 P m {j n-1 jj (c) r1.

.N 1 . )cH-eCH2h0-fCH2CH20)—(C-L-0)-H i) hydrolysis r2x p m II n of -0"M' 0 and/or (d) ii) elimination of protecting groups R1, R1 ^ ox )cH-(CH2)-0-fCH2CH20)—(C-L-0)—H H P " 0 " CD') 17 D ^ R\ )CH-fCH2)-(HCH2CH20)—(C-L—0>~ acyl or i) acylation g2 p m II n ether ii) etherifi- cation (E) or C1S02<SV€H3 D — ^ )0H-eCH2)-0-^CH2CH20)—(C-L-0)—S02<5)-€H: R P m 0 n (F) M OC-CHSH, or — NH2 •I I „ 0 R or alkalihydrosulfide gi SH or NH2 )ch^ch2>-(Kch2ch2o>—(C-L-0)—c-ch r?2 p m H n II l_ K 0 0 R - (G) deprotection °\ (E), (F) or (D) ^ )c-^CH2>-0-- • •-(CH2)-Z W q (H) 18 Production of (B) from (A): Alkali metal acetal-protected alkoxide (A) is made to react with ethylene oxide to form compound (B) to which polyethylene oxide segment is added. Compound 5 (A) can be obtained by treating acetal-protected alcohol with a metallizing agent such as alkali metal like sodium and potassium; organic metal like sodium naphthalene, potassium naphthalene, cumylpotassium and cumylcesium; or metal hydride like sodium hydride or 10 potassium hydride.

The above reaction from (A) to (B) is made to occur without solvent, or preferably in an anhydrous, aprotic solvent, and at a temperature in a broad range, e.x., -50t! - 300°C , preferably 1CC - 60"C , convenient-15 1 y at a room temperature (20^ - 30"C ). The reaction may be conducted either under pressure or under reduced pressure. Examples of solvent used include, not re-strictively, benzene, toluene, xylene, tetrahydrofuran, dioxane and acetonitri1e. Examples of reactor include, 20 not restrictively, round flask, autoclave and pressure sealed tube. Reactor is preferably sealed airtight, and is more preferably filled with inert gas. The concentration of reaction liquid is 0.1 to 95 % by weight, preferably 1 to 80 % by weight, most preferably 3 to 10 25 % by weight.

Production of (C) from (B): A reaction mixture containing (B) is allowed to react with lactide or lactone to form a living block 30 copolymer (C) wherein polyester segment is added via q-terminal hydroxyl group of polyethylene oxide. The — condition of this reaction can be almost the same as the above "reaction from (A) to (B). Usable lactide or lactone is capable of forming such a chain as has been 3 4 defined with regard to R and R of L of formula (I). Examples of preferable lactide include, not restrictive- 19 1 y, lactide of lactic acid and lactide of glycolic acid. Examples of usable lactone, on the other hand, include 0-propiolactone, y-butyro1 actone, S-valerol actone and 6-capro1 actone. Among these, y-butyrolactone and 5 5-valerolactone are preferable from the viewpoint of easy reactivi ty.

In the above steps, the proportion of polymerization initiator to ethylene oxide, lactide or lactone is, in molar ratio, 1:1 to 1:10,000, more preferably 1:5 10 to 1:10,000, most preferably 1:10-200 to 1:50-200.

The process of this invention not only makes it possible to adjust molecular weight of each segment according to the ratio of monomer used to polymerization initiator, but also provides a mono-dispersed or 15 mono-modal block copolymer wherein each of the formed segments has a very narrow molecular weight distribution.

The living polymer (C) itself which is obtained in the above manner is included in the polymer of 20 this invention. The alcoholate (C), however, can be converted (i) into polymer (D) by partial hydrolysis under a moderate condition (i.e., only adding water), or (ii) into polymer (D') which has an aldehyde group at a-terminal and a hydroxyl group at to-terminal by means 25 of treating (C) under a condition wherein acetal can be simultaneously hydrolyzed. The latter hydrolysis can be carried out with use of acids such as trif1uoroacetic acid, hydrochloric acid, sulfuric acid, nitric acid, formic acid and hydrogen fluoride, or alkalis such as 30 sodium hydroxide and potassium hydroxide, and, if necessary, with heating. - Production of (E) - (G) from (D): ~ (D) i s made to react wi th 35 (i) acetic acrylic acid, methacrylic acid or 7 P-tol uenesu 1 foni c acid to form an o)-terminal acyl compound, or (ii) a halide represented by formula (V) hal o-E (V) wherein halo and E in formula (V) correspond to groups other than acyl group in —(CH,-)- Z in formula (I) l q to form an a-terminal ether compound.

The above reactions can be conducted by known esterification or etherification process. As for organic acid in the above (i), it is convenient to use a reactive derivative of organic acid such as acid anhy-15 dride and acid halide.

When a mercapto group is to be introduced onto the a-terminal, it is useful to make a p-to 1 uenes ul f o-nated compound (F) react with an electrophi1ic agent such as thiosodium acetate, thiopotassium acetate or 20 potassium hydrosulfide so that a thioester group may be introduced onto the a-terminal, and thereafter to treat said thioester group with acid or alkali, and, then, there can be obtained a polymer represented by (G).

When an amino group is to be introduced onto the a-terminal, it is useful to hydrolyze (D) with use of an e1ectrophi 1ic agent such as N-(2-bromoethyl)- phthalimide, N-(3-bromopropyl )phthal imide, 1-bromo-2- (benzenami no)ethane or N-(2-bromoethyl)benzyl carbamate, and thereafter to conduct an alkali or acid treatment so 1 2 as to eliminate the groups R and R , and to simultaneously hydrolyze a-terminal imide bond, and, thus, — there can be obtained a polymer which has an amino gro-up at a-terminal . 1 2 Elimination of the groups R and R from 35 polymers (D), (E), (F) and (G) for the purpose of ob-7 taining a-terminal aldehyde can be conducted by the 21 above-mentioned conversion from (C) to (D'). As for the recovery of polymer from the reaction liquid, it can be carried out by solvent precipitation of the polymer per se, gel filtration chromatography, dialysis, ultrafil-5 tration or the like.

In this manner, there can be obtained various kind of heteroteleche!ic block copolymers represented by formula (I) of this invention. The obtained polymer (except living polymer) is capable of forming a high-10 molecular micelle which is very stable in an aqueous sol vent.

This high-molecular micelle can be prepared-by, for example, subjecting a polymer solution or suspension to a heating treatment, an ultrasonification 15 treatment and an organic solvent treatment, separately or in combination. Heating treatment is conducted by dispersing or dissolving a mixture of one or more species of block copolymers of this invention in water at a temperature ranging from 30 - 100*0 , more preferably 30 20 - 50t; - Ul tr asoni f i cati on is conducted by dispersing a mixture of one or more species of block copolymers in water in a range from 1W to 20W for one second to 24 hours, preferably in a range from 1W to 3W for three hours.

Organic solvent treatment is conducted by dissolving a mixture of one or more species of block copolymers in an organic solvent, dispersing the resulting solution in water and thereafter evaporating the organic solvent. Examples of the organic solvent in-30 elude chloroform, benzene, toluene, methylene chloride, etc. - It is also possible to prepare the hi gh-mol e-c-ular micelle of this invention by dissolving said mixture in methanol, ethanol, tetrahydrofuran, dioxane, 35 dimethy1sulfoxide, dimethylformamide or the like, and thereafter dialyzing the resulting solution against an 22 aqueous solvent. The fractional molecular weight of the membrane used for the dialysis is not restricted since optimal value varies according to the molecuar weight of block copolymer to be treated. Generally, however, the 5 fractional molecular weight is at most 1,000,000, preferably 5,000 - 20,000.

As an aqueous solvent, there can be employed water and buffer solution. The proportion of the aqueous solution used to the above organic solvent in dialy-10 sis is generally 1 to 1000 times, preferably 10 to 100 times. Temperature is not restricted in particular. Normally, the treatment is conducted at 5 - 25°C .

Thus produced high-molecular micelle of this invention has a critical micelle concentration as low as 15 4-12 mg/(, and is much more stable in an aqueous solvent than low-molecular micelle such as liposome which has widely been given consideration as a carrier for drug delivery. This means that, when administered into blood, the high-molecular micelle of this invention 20 is expected to significantly increase in half-life in blood, and, thus, it can be said that the polymer of this invention has excellent properties as a carrier for d rug de1i very .

Below, this invention is explained in more 25 detail with the working examples, but these working examples do not limit the area covered by this invention 1 n any way.

Example 1 THF 20 ml, 3, 3-diethoxypropanol 0.15 g, and a potassium naphthalene 0.5 mol/L-te t ra hyd ro f u ran soluti-on 2 ml was added to the reaction container and agitated -for 3 minutes in an argon atmosphere; a potassium com-~ pound of 3, 3-diethoxypropanol (potassium 3, 3-diethoxy- propanoxide) was produced. 7 Ethyleneoxide 8.8 g was added to this solution 23 and agitated at room temperature and 1 atm. After reacting for two days, lactide 7.2 g was added quantitatively to this reaction solution and then agitated for one hour. This solution was poured into cooled propanol 5 and the polymer produced was precipitated. The precipitate attained through centrifugal separation was refined by freeze drying from benzene. This yield was 15.0 g (94%). The polymer attained through gel permeation chromatography was mono-modal, the molecular weight of 10 the polymer was 16,000 (Figure 1).

According to the proton nuclear magnetic resonance spectra in the chloroform deuteride of tlie _ polymer attained, this polymer was confirmed to be the heterotelechelic oligomer having both units of polyeth-15 ylene oxide (PEO) and polyactide (PL) and quantitatively having acetal group on the a-terminal and hydroxy group on the a-terminal (Figure 2). The number average molecular weight of each segment of the block polymer determined by the integral ratio of the spectra were 8800 for 20 PEO and 7000 for PL.

Example 2 THF 20 ml, 3, 3-diethoxypropanol 0.15 g, and a potassium naphthalene 0.5 mol/L-tetrahydrofuran solution 25 2 ml was added to the reaction container and agitated for 3 minutes in an argon atmosphere; a potassium compound of 3, 3-diethoxypropanol (potassium 3, 3-diethoxy-propanoxide) was produced.

Ethylene oxide 5.7 g was added to this solu-30 tion and agitated at room temperature under 1 atm.

After reacting for two days, lactide 7.2 g was added %o this reaction solution and agitated for one hour. Thi-s solution was poured into cold propanol and the polymer"-produced was precipitated. The precipitate attained 35 through centrifugal separation was refined by freeze 7 drying from benzene. This yield was 12.4 g (95%). The 24 polymer attained through gel permeation chromatography was mono-modal, the molecular weight of the polymer was about 12,000.

According to the proton nuclear magnetic 5 resonance spectra in the chloroform deuteride of the polymer attained, this polymer was confirmed to be the heteroteleche1ic oligomer having both units of polyethylene oxide (PEO) and polylactide (PL) and quantitatively having acetal group on the a-terminal and hydroxy 10 group on the co-terminal. The number average molecular weight of each segment of the block polymer determined by the integral ratio of the spectra were 5400 for PEO and 6600 for PL.

Example 3 THF 20 ml, 3, 3-diethoxypropanol 0.15 g, and a potassium naphthalene 0.5 mol/L-tetrahydrofuran solution 2 ml was added to the reaction container and agitated for 3 minutes in an argon atmosphere; a potassium com-20 pound of 3, 3-diethoxypropanol (potassium 3, 3-diethoxy-propanoxide) was produced.

Ethylene oxide 8.8 g was added to this solution and agitated at room temperature under 1 atm.

After reacting for two days, 5-valero1 actone 5.0 g was 25 added to this reaction solution and agitated for one hour. This solution was poured into cold propanol and the polymer produced was precipitated. The precipitate attained through centrifugal separation was refined by freeze drying from benzene. This yield was 13.5 g 30 (97%). The polymer attained through gel permeation chromatography was mono-modal, the molecular weight of the polymer was about 14,000.

According to the proton nuclear magnetic ~ resonance spectra in the chloroform deuteride of the 35 polymer attained, this polymer was confirmed to be the 7 heteroteleche1ic oligomer having both units of polyeth ylene oxide (PEO) and poly(6-valerol actone) (PVL) and quantitatively having acetal group on the a-terminal and hydroxy group on the ^-terminal (Figure 3). The number average molecular weight of the block polymer determined 5 by the integral ratio of the spectra were 8800 for PEO and 5200 for PVL.

Example 4 2.0 mol/L-HCl 50 ml was added to methanol 50 10 ml in which the block copolymer sample attained in Example 2 was dissolved and this was agitated 1 hour at room temperature. After this solution was neutralized with NaOH aqueous solution, four hours of dialysis (fractional molecular weight 1000) was performed against 15 20 times the amount of water and this was refined by freeze drying. The yield was 0.85 (85%). The molecular weight of the polymer attained through gel permeation chromatography was confirmed to be unchanged from that before the reaction.

According to the proton nuclear magnetic resonance spectra in the chloroform deuteride of the polymer attained, the acetal group disappeared from the a-terminal of this polymer and instead a peak originating with the aldehyde was observed; it was confirmed to 25 be a heterote1echel ic PEO/PL oligomer quantitatively having an aldehyde group on the a-terminal and a hydroxy group on the a-terminal (Figure 4).

Example 5 Pyridine 20 ml and methacrylic anhydride 1.0 g were added to chloroform 20 ml in which 1.0 g of the -block copolymer sample attained in Example 2 was dis— solved" and this was agitated 24 hours at room tempera-" ture. This solution was neutralized and rinsed with a 35 hydrochloric acid aqueous solution. The chloroform 7 phase was poured into cold propanol and the polymer was 26 precipitated. The precipitate attained through centrifugal separation was refined by freeze drying from benzene. This yield was 0.8 g (80%). The molecular weight of the polymer attained through gel permeation ch roma-5 tography was confirmed to be unchanged from before the reacti on.

According to the carbon nuclear magnetic resonance spectra in the chloroform deuteride of the polymer attained, the peak originating with the hydroxy 10 group on the a-terminal of this polymer disappeared completely and instead a peak derived from the methacryloyl group was expressed, the polymer was confirmed to be a heterotelechelic PEO/PL oligomer quantitatively having an acetal group on the a-terminal and a 15 methacryloyl group on the a-terminal (Figure 5).

Example 6 Potassium naphthalene 0.5 mol/L-tetra-hydrofuran solution 2 ml and allyl bromide 5 ml were 20 added to tetrahydrofuran 20 ml in which the block copolymer 1.0 g attained in Example 2 was dissolved and agitated for four hours at room temperature. The reaction product attained was poured into cold propanol and the polymer was precipitated. The precipitate attained 25 through centrifugal separation was refined by freeze drying from benzene. This yield was 0.98 g (98%). The molecular weight of the polymer attained through gel permeation chromatography was confirmed to be unchanged from before the reaction.

According, to the carbon nuclear magnetic resonance spectra in the chloroform deuteride of the — polymer attained, the peak originating with the hydrox-y group on the a-terminal of this polymer disappeared ~ completely and instead a peak derived from the allyl 35 group was expressed; the polymer was confirmed to be a heteroteleche1ic PEO/PL oligomer quantitatively having 27 an acetal group on the a-terminal and an allyl group on the a-terminal (Figure 6).

Example 7 Potassium naphthalene 0.5 mol/L-tetrahydro- furan solution 2 ml and paratoluene sulfony1chloride 5 g were added to the tetrahydrofuran 20 ml in which the block copolymer sample 1.0 g attained in Example 4 was dissolved and this was agitated for 4 hours at room 10 temperature. The reaction product attained was poured into cold propanol and the polymer was precipitated. The precipitate attained through centrifugal separation was refined by freeze drying from benzene. This yield was 0.95 g (95%). The molecular weight of the polymer 15 attained through gel permeation chromatography was confirmed to be unchanged from before the reaction.

According to the carbon nuclear magnetic resonance spectra in the chloroform deuteride of the polymer attained, the peak originating with the hydroxy 20 group on the o-terminal of this polymer disappeared completely and instead a peak derived from the paratoluene sulfonyl group was expressed; the polymer was confirmed to be a heterotelechelic PEO/PL oligomer quantitatively having an acetal group on the a-terminal 25 and a paratoluene sulfonyl group on the o-terminal (Figure 7).

Example 8 The block copolymer 50 mg attained in Example 30 2 is dissolved in water or an appropriate buffer solution so as to become 0.01-0.1% (w/v). When the mice"He formation in these solutions was confirmed with partiele size distribution measurement by dynamic light scatter^ ing, the formation of a single polymer micelle with 35 average grain diameter 30 nm was confirmed (Figure 8). The critical micelle concentration of this polymer 28 micelle was 10 mg/L.

Example 9 A reactor was charged with 30 ml of THF, 0.13 5 g of 3, 3-diethoxypropano1 and 2 ml solution of potassium naphthalene dissolved in tetrahydrofuran in a concentration of 0.5 mol/L-tetrahydrofuran, and the resulting mixture was stirred for three minutes in an argon atmosphere, and, thus, there was formed a potassium deriva-10 tive (potassium 3, 3-diethoxypropanoxide) of 3, 3-diethoxypropanol.

There was added 7.0 g of ethylene o-xide to_the resulting solution, which was then stirred at 1 atm and at a room temperature. After two days-reaction was 15 over, 7.2 g of lactide of lactic acid was added to the reaction liquid, which was then stirred for further one hour. Thus produced solution was poured into cooled propanol so as to precipitate the formed polymer. Centrifugalized precipitate was purified by freeze 20 drying from benzene. The yield was 11.5 g (79 %). The polymer obtained by gel permeation chromatography was mono-modal and had a number average molecular weight of 11,000.

Proton nuclear magnetic resonance spectra of 25 the obtained polymer in chloroform deuteride taught that this polymer was a heterotelechelic oligomer which had both units of polyethylene oxide (PEO) and polylactide (PL) and which quantitatively had an acetal group at the a-terminal and a hydroxyl group at the a-terminal . As 30 for the number average molecular weight of each segment of this block polymer obtained from integral ratio of— the spectra, it was 5800 for PEO, and 5100 for PL.

There was dissolved 200 mg of the obtained ~ block polymer into 40 ml of dimethylacetamide, and the 35 resulting solution was dialyzed against water with use of dialytic membrane having a fractional molecular 29 weight of 12,000 - 14,000 over a period of 24 hours (water was exchanged after 2, 5 and 8 hours, each two liters). Dynamic light scattering measurement of the obtained solution taught that there had been formed 5 high-molecular micelle having an average particle size of 40 nm. The critical micelle concentration of this micelle was 5 mg/{.

Example 10 There was added dropwise 0.1 N hydrochloric acid to 10 ml of micelle solution obtained in Example 9 so that pH might be adjusted to 2, and, then, the solution was stirred for two hours at a room temperature.-Thereafter, the solution was neutralized with 0.1 N 15 aqueous solution of sodium hydroxide, and, then, the resulting solution was dialyzed against water with use of dialytic membrane having a fractional molecular weight of 12,000 - 14,000 over a period of 24 hours (water was exchanged after 2, 5 and 8 hours, each two 20 liters). Dynamic light scattering measurement of the obtained solution taught that there had been formed high-molecular micelle having an average particle size of 40 nm. The critical micelle concentration of this micelle was 5 mg/{.

This micelle solution was freeze-dried, and then was dissolved in dimethylsulfoxide deuteride and was subjected to NMR measurement. It was found that the signal derived from acetal group at 1.2 ppm and 4.6 ppm had almost completely disappeared, and there was ob-30 served signal derived from hydrogen of carbonyl methylene and hydrogen of aldehyde at 2.7 ppm (t) and 9.8~ppm (s) respectively. From area ratio of the signal, it was found that 95 % of acetal had been hydrolyzed into a 1dehyd e.

Example 11 There was dissolved 200 mg of PEO/PL block polymer (number average molecular weight of each segment: PEO: 4,500; PL: 13,000), which had been synthe-5 sized in the same manner as in Example 1, into 40 ml of dimethy1acetamide, and the resulting solution was dia-1yzed against water with use of dialytic membrane having a fractional molecular weight of 12,000 - 14,000 over a period of 24 hours (water was exchanged after 2, 5 and 8 10 hours, each two liters). Dynamic light scattering measurement of the obtained solution taught that there had been formed high-molecular micelle having an average particle size of 30 nm. The critical micelle concentration of this micelle was 4 mg/ {.

Industrial applicability This invention provides a heterotelechelic oligomer or polymer which has different functional groups at both ends of its molecule and which has hydro-20 philic segment and hydrophobic segment in its main chain. It is expected from its constituent components that this oligomer or4 polymer will show excellent bioavailability. Furthermore, this oligomer or polymer is capable of forming high-molecular micelle which is 25 quite stable in an aqueous solvent.

It is therefore highly possible that the oligomer or polymer can be applied to living organism, or can be utilized in a field wherein a carrier for drug delivery is produced and/or used. <kj- ^ •) - / itess 31

Claims (16)

WHAT WE CLAIM IS: INTELLECTUAL PROPERTY OFFICE OF N.Z. 1 0 JUL 2001 RECEIVED

1 . A heterotelechelic block copolymer which is represented by formula (I) below: r1 )ch-(ch2>-(hch2ch203—(c-l-0)—<ch2>—z (1} R P m n n q 1 2 wherein R and R independently denote Cj ^g alkoxy or phenyl-C1_3 alkyloxy, or R1 2 and R , combined with each other, denote ethyl enedioxy (-0-CH(R')-CH2-0-: wherein R' denotes hydrogen atom or Cj _ g alkyl) which may be substituted with _g alkyl, or, combined with each other, denote oxy (= 0), R3 R4 L denotes - CH~0-C- CH- or —(CH2)- II r O 3 4 wherein R and R independently denote a hydrogen atom or alkyl, and r denotes an integer of 2 - 5, m denotes an integer of 2 - 10,000, n denotes an integer of 2 - 10,000, p denotes an integer of 1 - 5, q denotes an integer of 0 - 20, Z denotes, when q is 0 (zero), hydrogen atom, alkali metal, acetyl, acryloyl, methacryloyl, cinnamoyl, p-to1uenesulfony 1 , 2-mercaptopropionyl or 2-aminopropiony1, or allyl or vinylbenzyl, while, when q is an integer of 1 - 20, denoting C16 al koxycar-bonyl , carboxymercapto or amino. OFFICE OF N.Z. 1 o JUL 2001 RECEIVED 2 . The heteroteleche1ic block copolymer of claim 1 wherein R oxy. 1

2 and R , combined with each other, denote

3. The heterotelechelic block copolymer of claim 1 2 1 wherein R and R independently denote Cj_g alkoxy, or benzyloxy, or, when combined with each other, denote ethylenedioxy which may be substituted with Cj _ j al k yl .

4. The heterotelechelic block copolymer of claim 1 2 1 wherein R and R , combined with each other, denote 3 4 oxy; and, in L, both R and R are hydrogen atom or methyl, or r denotes an integer of 4; and q denotes an i nteger of 0 - 3.

5. The heterotelechelic block copolymer of claim 1 2 1 wherein R and R independently denote _g alkoxy; 3 4 and, in L, both R and R are hydrogen atom or methyl, or r denotes an integer of 4; and q denotes an integer of 0 - 3.

6. The heterotelechelic block copolymer of claim 1 wherein m denotes an integer of 10 - 200, and n denotes an integer of 10 - 200.

7. The heteroteleche1ic block copolymer of claim 1 2 1 wherein R and R , combined with each other, denote 3 4 oxy; and, in L, both R and R are hydrogen atom or methyl, or r denotes an integer of 4; and q denotes 0 (zero); and Z denotes hydrogen atom, acetyl, acryloyl, methacryloyl, cinnamoyl, p-to!uenesulfonyl, allyl or vinyl benzyl .

8. The heteroteleche1ic block copolymer of claim 1 2 1 wherein R and R independently denote _g alkoxy; 33 3 4 and, in L, both R and R are methyl, or r denotes an integer of 4; and q denotes 0 (zero); and Z denotes hydrogen atom, or sodium, potassium or cesium.

9. The heteroteleche1ic block copolymer of claim 1 2 1 wherein R and R , combined with each other, denote 3 4 oxy; and, in L, both R and R are methyl, or r denotes an integer of 4; and q denotes an integer of 1 - 3; and Z denotes Cj_g alkoxycarbonyl, carboxyl, mercapto or ami no.

10. A process to produce the heterotelechelic -block copolymer of formula (I) of claim 1 which comprises the following steps: Step (1) A polymerization initiator represented by the following formula (II) gi-i )CH-(CH23-0"M+ R2"1 P 1-1 2-1 wherein R and R independently denote jq alkoxy, or, combined with each other, denote ethylenedioxy which may be substituted with _ g alkyl, p denotes an integer of 1 - 5 and M denotes alkali metal is made to react with ethyleneoxide so that a compound represented by the following formula (III) may be produced: R1"1 ^CH-fCH2)-(H;CH2CH20) CH2CH2O M+ (III) R2-1 P m-1 34 1-12-1 wherein R , R , p and M are as defined in formula (II), and m denotes an integer of 2 - 10,000; Step (2) The compound of formula (II) is allowed to react with lactide or lactone which is represented by the following formula (Ill-a) or (Ill-b): o r J) R3—CH" XC=0 0=CL .CH—R4 V (\=0 \ch 2)^ (III-a) (Ill-b) 3 4 wherein R and R independently denote hydrogen atom, alkyl, aryl or aryl-Cj_g alkyl, and r denotes an integer Of 2 - 5, so that a block copolymer represented by the following formula (IV) may be formed: r1-1 _ + XH-fCH2>-0-(CH2CH20)—(C-L-O) C—fc—0 M r2"1 p 10 ii n-l u u u (IV) wherei n R3 R4 I I L denotes -CH-O-C-CH- or _£CH2}- II T 0 1-1 2-1 and R , R , p, m, n and M are as defi ned above; 35 and, in addition under circumstances, Step (3) (i) The alkali metal al koxi de of formula (IV) is selectively hydrolyzed to form a block copolymer of the following formula (V) Ri-i )cH-fCH2)-(KCH2CH20)—(C-L-0)—H p2-r p m II n 0 1-1 2-1 wherein R , R , p, m, L and n are as defined above; or - (ii) the block copolymer of formula (IV) is completely hydrolyzed to form a block copolymer of the following formula (VI) °\ >H-6CH2)-(HCH2CH20)—(C-L-O)—H ( VI} fl P m n n wherein p, m, n and L are as defined above; Step (4) The block copolymer of formula (V) is allowed t o reac t wi th (i) acetic acid, acrylic acid, methacrylic acid, cinnamic acid or p-toluenesul fonic acid, or a reactive derivative thereof, or (ii) allyl halide or vinylbenzyl halide, or (iii) a halide represented by the following formula (VI I) X-fCHz^-Z' (VII) q wherein X is chlorine, bromine or iodine, q' is an integer of 1 - 20 and Z' is Cj _ g '0 ; INTELLECTUAL PRUPtKIT, OFFICE OF N.Z. 36 1 0 JUL 2001 RECEIVED alkoxycarbonyl or a protected amino; and, under circumstances, Step (5) The p-toluenesulfonic ester derivative produced in (i) of Step (4) is subjected to transe-sterification, or the derivatives produced in (i), (ii) or (iii) of Step (4) are subjected to hydrolysis reaction.

11. A polymeric micelle which comprises the heteroteleche1ic block copolymer of claim 1 as an active component in an aqueous solvent.

12. The polymeric micelle of claim 11 wherein Z denotes a group other than alkali metal in the hetero-telechelic block copolymer of formula (I) of cl aim 1 .

13. The polymeric micelle of claim 11 wherein Z denotes a group other than alkali metal while R1 and 2 R , combined with each other, denote oxy in the heterot eleche1ic block copolymer of formula (I) of claim 1 .

14. The heterotelechelic block copolymer according to any one of claims 1 to 9, substantially as herein before described with reference to the Examples.

15. A process according to claim 10, substantially as herein before described with reference to the Examples.

16. A polymeric micelle which comprises the heterotelechelic block polymer of claim 14 as an active component in an aqueous solvent.