Description

The subject matter of the present application is a process for the manufac¬ ture of polymers having repeating units comprising spiro orthoester groups, the polymers obtained thereby and their use for the manufacture of strain free composites, high strength adhesives. additives to other mon¬ omer mixtures to control the amount of shrinkage or expansion upon poly¬ merization and specifically in dental filling materials.

US-A-4387215 already discloses that polymers formed by the polymeriza¬ tion of polycyclic ring-opening monomers, such as monomers comprising spiro orthoester groups, spiro orthocarbonate groups and polycyclic ketal lactone groups show near zero shrinkage or expansion during polymeriza¬ tion and are therefore usable for the manufacture of strain-free compos¬ ites, high strength adhesive, precision castings and specifically binders for propellants.

The subject matter of DE-A-248597 is a method for the manufacture of ho- mopolymers comprising spiro orthoester groups of the following formula

wherein R ² is hydrogen or methyl and X is halogen.

Said homopolymers are stated to be useful as adhesives. casting resins, protection coatings and for dental materials. The homopolymers are man¬ ufactured by the radical polymerization of 2-halomethyl-8.8-dimethyl-9- (meth)acryloyloxy- l ,4.6-trioxaspiro[4.4jnonanes. However, this process is not fully satisfying with respect both to the manufacture of the starting materials and their polymerization.

The object of the present invention therefore is the provision of an im¬ proved process for the manufacture of polymers having repeating units comprising spiro orthoester groups which provides the products from easi¬ ly available starting products with high purity and high yields, novel poly- mers obtained thereby and their use.

The subject matter of the present application therefore is the process ac¬ cording to claim 1. The subclaims comprise preferred embodiments of this process, novel polymers obtainable by this process and the use of these polymers.

The subject matter of the present invention therefore is a process for the manufacture of polymers having repeating units comprising spiro ortho - ester groups of the following general formula I

wherein

A is C i. -alkylene, C i .g-alkyleneoxycarbonyl or an oxygen-car¬ bon bond.

R ¹ is hydrogen or methyl.

R ² is C i.g-alkyl or C i.g-alkyl substituted by C ι _g-al- koxy or aryloxy,

R3 and R ⁴ independently are hydrogen or C i_g-alkyl,

R5 is hydrogen or methyl.

R ⁶ is hydrogen, methyl, phenyl. carboxy, carboxy-Ci _6-alkyl, carboxamido or cyano. n is an integer > 1 and m is 0 or an integer >1. with the proviso that the molecular weight of the polymer is between 500 and 1 000 000. which is characterized by reacting a polymer having repeating units com-

prising lactone groups of the following general formula II

wherein A, R ¹ . R^, R ⁴ . R^, R^, n and m are as defined above, with an oxi- rane compound of the following general formula III

°^ (HI)

R ²

wherein R ² is as defined above.

According to a preferred embodiment A is a methylene group, an ethylene oxycarbonyl group or an oxygen-carbon bond. R ¹ preferably is methyl. R ² preferably is C i .g-alkyl substituted by phenoxy and more preferably phe- noxymethyl. R^ and R ⁴ preferably are hydrogen or methyl. R^ preferably is hydrogen or methyl. Preferably m is 0 and n is an integer such that the mo¬ lecular weight of the polymer is between 500 and 500.000. more preferably between 1.000 and 50.000 and most preferably between 25,000 and 45.000.

According to a preferred embodiment of the process of the present inven¬ tion the reaction is carried out in an organic solvent, such as benzene, dichloromethane, trichloroethylene, dichloroethylene. carbontetrachlo- ride, chlorobenzene. nitrobenzene and cyclohexane. more preferably in anyone of the halogenated organic solvents inert to the reaction and most preferably in dichloromethane. The reaction of the starting material of for¬ mula (II) with the oxirane compound of the general formula (III) is prefer¬ ably carried out in the presence of a catalyst or more preferably in the pres¬ ence of a Lewis acid catalyst, such as boron trifluoride, boron trifluoride

etherate, aluminum trichloride, tin dichloride, tin tetrachloride, titanium tetrachloride and iron trichloride. The reaction can be carried out at room temperature at a reaction time of 1 to 5 hours, preferably 2 to 4 hours.

According to a further preferred embodiment of the present invention, the starting compound of general formula (II) is manufactured by radical poly¬ merization of a 2-oxo-tetrahydrofurane derivative of the following general formula (IV)

wherein A. R ¹ , R3 and R ⁴ are as defined above. For the manufacture of a copolymer of the above formula (I) , wherein m is an integer of > 1 , the poly¬ merization is carried out in the presence of a copolymerizable monomer of the following general formula (V)

wherein R^ and R^ are as defined above. Specifically preferred copolyme¬ rizable monomers of formula (V) are ethylene, propylene, (meth)acrylic acid and the esters thereof, acrylonitrile, acrylamide. styrene and the like.

The polymerization yielding the starting compounds of formula (II) is pref¬ erably carried out in solution in an inert organic solvent and in the pres¬ ence of a radical forming catalyst. As the organic solvent preferably an aro¬ matic solvent, such as toluene is used. As the catalyst a free radical form¬ ing catalyst useful for such polymerizations can be used, such as a perox¬ ide catalyst or more preferably azobisisobutyronitrile.

The subject matter of the present application further are polymers having repeating units comprising spiro orthoester groups of the following gener¬ al formula (I)

wherein A, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , m and n are as defined above. Specifical¬ ly preferred polymers are homopolymers having repeating units compris¬ ing spiro orthoester groups of the following general formula VI

wherein

A is C ^.g-alkylene, C ι -5-alkyleneoxycarbonyl or an oxygen-car¬ bon bond,

R ¹ is hydrogen or methyl.

R3 and R ⁴ independently are hydrogen or C i.g-alkyl. n is an integer > 1 with the proviso that the molecular weight of the polymer is between 3 000 and 50 000.

The process of the present invention is specifically advantageous, in that the polymers having useful properties are easy to synthesize from readily available starting material and provides the products with high yield and high purity. The 2-oxo-tetrahydrofurane derivatives of the following gen¬ eral formula (IV)

wherein A, R* , R ³ and R ⁴ are as defined above, can be manufactured with ease by reacting the corresponding lactone of formula (VI) 0

^ with (meth)acryloyl chloride.

Specifically preferred polymers corresponding to the above general formu¬ la (I) are the following:

⁵ Homopolymers having repeating units comprising spiro orthoester groups of the following general formula VI

wherein

A is C ι -.6-alkylene. C ι -.6- ^a **kyleneoxycarbonyl or an oxygen-car-

bon bond,

R ! is hydrogen or methyl,

R3 and R ⁴ independently are hydrogen or C ^.g-alkyl, n is an integer > 1 with the proviso that the molecular weight of the polymer is between 3 000 and 50 000.

poly-{ l -methyl- l -[2-(phenoxymethyl)- 1.4, 6-trioxaspiro(4.4]nonane-7- yl]methoxycarbonyl]ethylenes} having the formula 4

and a molecular weight in the range of 5 000 to 500 000, preferably 20 000 to 40 000.

poly-{ 1 -methyl- 1 - [2- (phenoxymethyl)- 1 ,4.6- trioxaspiro [4.4]nonane-7- yl)carbonyloxy-ethoxycarbonyl]ethylenes} having the formula 8

and a molecular weight in the range of 5 000 to 50 000. and

p.oly-U -methyl- 1 - [2 -(phenoxymethyl) -8.8-dimethyl- l , 4, 6-trioxaspi-

ro[4.4]nonane-9-yl)oxycarbonyl]ethylenes} having the formula 12

and a molecular weight in the range of 5 000 to 500 000. preferably 20000 to 40 000.

The above homopolymers preferably have a molecular weight in the range of 5.000 to 50,000. more preferably between 10.000 and 40.000 and even more preferred between 25.000 and 35.000.

The polymers of the present invention comprise pending spiro orthoester groups, which can be subjected to ring opening polymerization. As is known from US-A-4 387 215. this ring-opening polymerization has the ef¬ fect that the polymer does in contrast to normal polymerization not show shrinkage but no shrinkage or even slight expansion caused by the ring opening, as can be demonstrated by the following scheme, showing that in dependency from the attack of the electrophilic agent at the 0- 1 atom or 0- 4 atom two different polymer structures are obtained:

15

30

35

Therefore, the polymers of the present invention are highly advantageous, in that they can be used to provide strain free hardenable compositions providing hardened products, which have a controlled amount of shrink¬ age or expansion, an effect very desirable for example in dental filling com¬ positions, which should most closely fit to the tooth to be restored.

The properties of the polymers of the present invention can be controlled as desired by the proper selection of the pending spiro orthoester groups and the fact as to whether copolymerizable monomers are present and what kind of copolymerizable monomers they are. On the basis of these copoly-

merizable monomers further properties of the corresponding copolymers can be provided.

The preferred homopolymers of the present invention can be used as such or blended with other polymers, fillers, reinforcing fibers and additives usual for the manufacture of composites and casting resins and specifical¬ ly dental filling compositions. Therefore, the present invention provides for the possibility of tailoring the polymers according to the desired proper¬ ties of the final hardened product.

A further subject matter of the present invention therefore is the use of the above polymers which are capable of expanding upon reaction of the spiro orthoester groups for the manufacture of strain free composites, high strength adhesives. as additives to other monomer mixtures to control the amount of shrinkage or expansion upon polymerization and specifically for the manufacture of dental filling materials. For this type of utility, the polymers of the present invention are mixed with usual fillers, pigments, hardeners and usual additives.

During their use the polymers of the present invention are subjected to a ring opening polymerization providing the expansion of the polymer. This polymerization is preferably initiated by catalysts which generate cations during radiation. As such catalysts diaryliodonium salts, organometallic salts, such as U3 ⁵ -2,4-cyclopentadiene- l-yl)[( l,2,3.4.5,6-J3)-( l-methyl- ethyl)-benzene]-iron(I)hexyΩuorophosphate and triarylsulfonium salts may be used. These catalysts are mixed with polymers and additional com¬ ponents, such as pigments, fillers and etc.. brought to the desired shape, such as the filling of a cavity in a tooth, and are then subjected to the ring opening polymerization by irradiation with actinic light, such as ultravio- let light.

The present invention can be explained more in detail by making reference to the following examples.

Example 1

Poly-( l -methyl- 1- [2- (phenoxymethyl)- 1.4.6-trioxaspiro [4.4]nonane-7- yl _. methoxycarbonyl] ethylene}

a) synthesis of 5-(methacryloyloxymethyl)-2-oxo-tetrahydrofurane (2)

0

5-Hydroxymethyl-2-oxo-tetrahydrofurane ( 1) was obtained according to the method of R.M. Silverstein (Tetrahedron. 34. ( 1978) 1449). To the alco¬ hol ( 10, 1 g. 87 mmol) were added 100 ml dichloromethane and 8.4 ml ( 104 mmol) pyridine; the mixture was cooled to - lO\'C. Then a solution of 40 ml 5 dichloromethane and 8.3 ml (87 mmol) methacryloyl chloride were added dropwise during a period of 1.5 h. The solution was stirred overnight at room temperature. The solvent was evaporated and the residue was chro- matographed on silica gel (ethylacetate/hexane (2 : 1)).

° Yield: 13.4 g = 83.5 %

IR-spectrum: (v cm ^{\' 1} , KBr)

2959 (CH ₃ ); 2934 (CH ₂ ); 1779 (C = O. lactone); 1720 (C = O); 1637 (C = C); 1 153 (C - O); 1074 (C-O-C): 886 (= CH ₂ ). 5

^-NMR-spectrum: (δ in ppm. 200 MHz, CDC1 ₃ )

6. 14 (m. 1H, = CH ₂ cis): 5.63 (m, 1H = CH ₂ trans) . 4.8 (m. 1H. CH); 4.32

(d/d. 2H, CH 0) : 2.61 (m. 2H. CH ₂ ); 2.39 (m. 2H. CH ₂ ); 1.95 (t. 3H. CH3).

0 ¹³ C-NMR-spectrum: (δ in ppm. 50.3 MHz, CDCI3)

176.4 (C = O. lactone); 166.7 (C = O); 135.5 (C - CH ₃ ); 126.3 (= CH ₂ ); 77.2 (CH ₂ - O) ; 65.4 (0-CH-CH ₂ ); 28.0 (C ^δ ); 23.8 (C-* ³ ); 16. 1 (CH3).

b) Radical polymerization of 5-(methacryloyloxymethyl)-2-oxo-tetrahy- 5 drofurane (2)

20h

(2) (3)

To a solution of 1.8 g (9.7 mmol) 5-(methacryloyloxymethyl)-2-oxo-tetra- hydrofurane (2) were added 40 ml toluene and 15.9 mg (1 mol%) azobislso- butyronitrile (AIBN). The mixture was heated to 70\'C on an oil bath for 20h and then the solvent was evaporated. The oily product was dissolved in 5 ml dichloromethane and precipitated in hexane. The colorless polymer was filtered and dried in vacuo.

Yield: 1.66 g = 92%.

IR-spectrum: (v In cm" ¹ , KBr)

2955 (CH ₃ ); 1778 (C = O. lactone); 1731 (C = 0); 1 156 (C - 0); 1071 (C-O-C).

^-NMR-spectrum: (δ in ppm. 200 MHz. DMSO-d ₆ . T = 100\'C)

4.9 - 4.65 (m. 1H. CH); 4.3 - 3.9 (m. 2H. CH ₂ 0); 2.64 - 2.23 ( . 4H. CH ₂ );

2. 18 - 1.68 (m. 2H, CH ₂ - CCH ₃ ) ; 1. 18 - 0.75 (s. 3H. CH ₃ ).

¹³ C-NMR-spectrum: (δ in ppm. 50.3 MHz. DMSO-d ₆ . T = 100\'C)

175.8 (C = O. lactone); 175.2 (C = O): 76.2 (CH ₂ - O); 65.6 (CΥ); 44.1 (C-

CH ₃ ); 27. 1 (C ^α ) ; 22.9 (C- ⁶ ): 16. 1. 16.7 (CH ₂ -C-CH ₃ ).

c) Synthesis of poly{ l -methyl- l [2-(phenoxymethyl)- l ,4,6-trioxaspiro [4.4]nonane-7-yljmethyloxycarbonyl}ethylene (4) via polymer analogous reaction

(3)

(4)

To a solution of 1.4 g (7.4 mmol) poly{-methyl- l [(2-oxotetrahydrofurane-5- yl)methyloxycarbonyl]}ethylene (3) were added 80 ml dichloromethane, 4 ml (30 mmol) 2.3-epoxypropylphenylether and 0.15 ml borontrifluoride etherate. The mixture was stirred at room temperature for 4 h, and the cat¬ alyst hydrolized with 5 ml aqueous sodium hydroxide, the organic layer was separated, dried and concentrated and the polymer precipitated by pouring the solution in ethanol.

IR-spectrum: (v in cm" ¹ , KBr)

3032 (CH. arom.) ; 2944 (CH ₃ ); 1779 (C = O, lactone); 1732 (C = 0); 1599 (C -

C, arom.); 1 152 (C-O-C) ; 756 (CH, arom.) . 692 (CH. arom.).

¹ H-NMR-spectrum: (δ in ppm. 200 MHz. CDCI3)

7.36-7.08 (m. 2H. H arom.); 7.00 - 6.71 (m. 3H. H arom.); 4.86 - 4.45 (m.

1H) 4.27 - 4.09.(m. 2H. CH ₂ -0-C=0); 4.09-3.09 (m. 5H, CH. CH ₂ ); 2.64-

1.64 (m. 4H, CH ₂ ) : 1.45 - 1. 16 (m. 2H, CH ₂ -CCH ₃ ); 1. 16 - 0.68 (m. 3H.

CH ₃ ) .

Example 2

Poly-( l -methyl- 1 - [2- (phenoxymethyl)- 1 ,4, 6-trioxaspiro[4.4lnonane-7- yl]carbonyloxy-ethoxycarbonyl]ethylene}

a) Synthesis of 5-{[2-(methacryloyloxy)ethyloxy]carbonyl}-2-oxo-tetrahy- drofurane (6)

The starting carboxylic acid (5) was synthesized according to the method of C. Herdeis (Synthesis, 232 ( 1986)). 6.5 g (50 mmol) of the carboxylic acid (5) were dissolved in 300 ml dichloromethane and cooled to - lO\'C. To the solution were added 1 1. g (55 mmol) dicyclohexylcarbodiimide, 6.7 ml (55 mmol) hydromethylmethacrylate and 0.61 g (5 mmol) N.N\'-dimethylamino pyridine (DMAP) . The mixture was stirred overnight, the dicyclohexylurea filtered off and the resulting filtrate extracted with water (3 times) , acetic acid and again with water. The organic layer was dried with Na ₂ S04 ^{an <} ^ the solvent evaporated. The solid was chromatographed on silica gel (dich- loromethane/ethylacetate (9 : 1) .

Yield: 10.8 g = 89.2 %

IR-spectrum: (v in cm" 1. KBr)

2968 (CH ₃ ); 1789 (C = O, lactone); 1748 (C = O); 1631 (C = C); 1 154 (C - O);

1064 (C-O-C).

¹ H-NMR-spectrum: (δ in ppm. 90 MHz, CDCI3)

6. 15 (s. 1H, = CH ₂ ); 5.6 (m. 1H, = CH ₂ ); 4.95 (m. 1H. CH-O); 4.4 (s. 4H.

CH ₂ -0): 2.6 (m. 4H. CH ₂ ) ; 1.95 (s. 3H, CH ₃ ).

¹³ C-NMR-spectrum: (δ in ppm, 50.3 MHz, CDCI3)

175.8 (C = 0. lactone) ; 169.6 (C = 0); 165.6 (C = 0): 131.5 (CH = CH ₂ ); 127.6 (=CH ₂ ) ; 75.4 (CH) ; 63.3 (CH ₂ -0); 61.6 (CH ₂ -0); 26.5 (CH ₂ ); 25.6 (CH ₂ ); 16. 1 (CH ₃ ).

b) Polymerization of 5-{[2-methacryloyloxy)ethyloxy]carbonyl}-2-oxo- tetrahydrofurane (6)

(6)

(7)

To a solution of 1.4 g (5.8 mmol) of (6) were added 50 ml toluene and 0.95 mg (0.1 mol%) AIBN. The mixture was heated to 80"C on an oil bath for 24 h. The solvent was removed under reduced pressure, the product dissolved in 5 ml dichloromethane and precipitated in hexane. The polymer was filtered and dried in vacuo.

Yield: 1.25 g = 89.3%

IR-spectrum: (v in ppm, KBr)

2966 (CH ₃ ); 1790 (C = O. lactone): 1706 (C = O) ; 1694 (C = O); 1 145 (C-O);

1061 (C-O-C)

¹ H-NMR-spectrum: (δ in ppm. 200 MHz, DMSO-dg)

5.35 (m. 1H. CΪH); 3.7 (m. 4H. 0-CH ₂ -CH ₂ -0); 2.6-2.36 (m. 2H. C ^α H ₂ );

2.36- 1.86 (m. 2H. CH-^H): 1.86- 1.45 (m. 2H. CH ); 1.2 (m, 3H. CH ₃ ) .

¹³ C-NMR-spectrum: (δ in ppm, 75.4 MHz, DMSO-d ₆ ) 176.33 (C = O, lactone) : 175.31 (C = O, ester) ; 169.7 (C=0. ester) ; 75.9 (CH); 62.58 (d,CH -CH ₂ -0) ; 44.37 (CH ₂ -C(CH ₃ )) ; 44.05 (C(CH ₃ )) ; 26.4 (CH ₂ ); 25. 15 (CH ₂ ); 18.06 (CH ₃ ).

c) Polymer analogous reaction of 5-{ l -methyl- l-[2-(2-oxo-tetrahydro- furane-2-yl)carbonyloxy]ethyloxycarbonyl}ethylene (7) with 2,3-epoxy¬ propylphenylether

(8)

To a solution of 0.75 g (3. 1 mmol) polyU -methyl- 1 [2-(5-oxotetrahydrofu- rane-2-yl)carbonyloxylethyloxycarbonyl}ethylene (7) was added 60 ml dichloromethane, 1.7 ml ( 12.4 mmol) 2,3-epoxypropylphenylether and 0.15 ml borontrifluoride etherate. The mixture was stirred at room tempe¬ rature for 4 h. the catalyst hydrolized with 5 ml of aqueous sodium hydro¬ xide. The organic layer was separated, dried, concentrated and the poly¬ mer was precipitated by pouring the solution in ethanol.

IR-spectrum (v in cm ^{- 1} , KBr)

303 1 (CH.arom.); 2944 (CH ₃ ) ; 1779 (C = O. lactone) ; 1706 (C = O) ; 1693 (C ^■ ■

O) ; 1599 (C-C arom.); 1 152 (C-O-C) ; 756 (CH. arom.); 692 (CH. arom.).

¹ H-NMR-spectrum: (δ in ppm. 200 MHz, CDC1 ₃ )

7.3 (m. 2H, H arom.) ; 6.9 (m. 3H. H arom.); 4.3-3.7 (m. 10H, CH ₂ 0);

2.23- 1.84 (m, 4H. CH ₂ ); 1.27 (m. 2H. CH ₂ -CCH ₃ ); 0.9 (m. 3H. CH ₃ ).

Example 3

Poly-{ 1 -methyl- 1 -[2-(phenoxymethyl)-8.8-dimethyl- 1 ,4,6-trioxaspi- ro[4.41nonane-9-yl _. oxycarbonyl]ethylene}

a) Synthesis of 4,4-Dimethyl-3-methacryloyloxy-2-oxo-tetrahydrofu- rane ( 10)

(9) (10)

8.2 g 4,4-Dimethyl-3-hydroxy-2-oxo-tetrahydrofurane (9) , 10.45 ml trie- thylamine (NEt ₃ ). 0.77 g 4-dimethylamino-pyridine (DMAP) were dissolved in 120 ml dichloromethane. At O\'C 6.02 ml methacryloyl chloride were add- ed dropwise and stirred for 3 h. After filtration the reaction mixture was ex¬ tracted with saturated sodium hydrogen carbonate, potassium hydrogen sulfate and saturated sodium chloride, dried (Na ₂ Sθ4.) , filtered and con¬ centrated by solvent removal under reduced pressure. The obtained pale yellow product was purified by column chromatography on silica-gel 60 (Merck, 70-230 mesh), elution with dichloromethane /ethylacetate (9 : 1).

Yield: 8.32 g = 66.6 %

¹ H-NMR-spectrum (CDCI3): δ = 1.2 (-C(CH ₃ ) ₂ - ,2s.6H); 2.0 (-CH ₃ . s. 3H): 4. 1 (-CH ₂ , s. 2H) ; 5.45 (-CH-. s, IH) ; 5.7 (=CH. m, IH) , 6.25 (=CH. m. I H)

IR-spectrum (KBr) (v in cm" ¹ ) : 3108 (w, s. =CH); 2970-2880 (s. aliphat. CH); 1792 (s. s. 0-C=0, lactone); 1727 (s. s, C=0); 1638 (s, s, C=C); 1350- 1050 (s, C-O-C) .

b) Poly-[4,4-dimethyl-3-methacryloyloxy-2-oxo-tetrahydrofurane] ( 1 1)

(11)

1.5 g of 4,4-dimethyl-3-methacryloyloxy-2-oxo-tetrahydrofurane ( 10) and 6.2 mg azobisisobutyronitrile (AIBN) were dissolved in 75 mlTHF and heat¬ ed to 80"C. The polymerization was carried out for 24 h in a constant tem¬ perature bath. The polymer was precipitated in hexane.

The molecular weight of polymer ( 1 1) determined by gel-permeation chromatography was M* = 18000.

Yield: 1.08 g = 72 % polymer

0.35 g = 23 % oligomers

lH-NMR-spectrum (CDC1 ₃ ): d = 1.2 (m, CH ₃ . 9H); 2. 1 1 (m. CH ₂ . 2H); 4.03 (s, CH ₂ 0, 2H); 5.28 (s. OCHC=0. 1 H)

IR-spectrum (KBr) , (v in cm ^{- 1} ): 2970-2880 (s. aliphat. CH); 1794 (s, s. O- C=0. lactone); 1741 (s. s. C=0); 1350- 1050 (s. C-O-C) .

(ID

c) Polymer analogous reaction of (II) with phenoxymethyloxirane

1.5 g poly(4.4-dimethyl-3-methacryloyloxy-2-oxo-tetrahydrofurane) (11) and 4.1 ml phenoxymethyloxirane were dissolved in 60 ml dichlorome¬ thane. 0.15 ml boron trifluoride etherate were added and the reaction mix¬ ture was stirred for 3 h. The mixture was extracted with sodium hydroxide and the organic layer was dried with Na ₂ Sθ4 ^an( *** evaporated. The polymer was precipitated in hexane.

The molecular weight of polymer (12) determined by gel-permeation chromatography- was M*^* = 35000.

Yield: 1.81 g

!H-NMR-spectrum (DMSO-d ₆ ) δ: 1.2 (m, CH ₃ , 9H); 2. 1 (m, CH ₂ , 2H); 3.3- 5.4 (m. CH ₂ . CH, 8H); 6.9 (m, C ₆ H ₅ . 3H) ; 7.2 (m. C ₆ H ₅ . 2H).

IR-spectrum (KBr) (v in cm" ¹ ): 3060, 3039 (w, ---C-H): 2967-2878 (s. ali- phat. C-H); 1794 (s, s, 0-C=0. lactone); 1738 (s.s. C=0); 1600 (s, s. arC-C); 1350- 1050 (s. C-O-C); 756, 692 (s, s, arC-H) .

^X H-NMR spectra were recorded on a CXP -200 FT-NMR and the IR-spectra on a FTIR 60 SRX-spectrometer. Gel-permeation chromatography analysis were carried out using a Waters apparatus with UV-detector and a Melz apparatus to detect the refractive index.

Molecular weights were determined by gel-permeation chromatography using THF as eluent and calibration with PMMA standards.