Polyacrylate-polysilane block copolymers

Abstract

The invention relates a polyacrylate-polysilane block copolymer of general structure (I): wherein m and n independent of one another, are integers ranging from 2 to 4000; p is an integer ranging from 0 to 5; q is an integer ranging from 1 to 5; R.sup.1 represents hydrogen, straight-chain or branched alkyl group having 1 to 4 carbon atoms; R.sup.2 represents hydrogen, straight-chain or branched alkyl group having 1 to 18 carbon atoms; R3 represents hydrogen, hydroxyl group, straight-chain or branched alkyl group having 1 to 4 carbon atoms, or an C.sub.6-C.sub.14 aryl group; L is a linking moiety representing amine (—NH—) group, amide (—C(O)NH—) group, urea (—NHC(O)NH—) group, urethane (—OC(O)NH—) group or methylene (—CH.sub.2—) group; R.sup.4, R.sup.5 and R.sup.6 independent of one another, represents hydrogen, straight-chain or branched, alkyl group having 1 to 8 carbon atoms or polydimethylsiloxane group; and R.sup.7 represents hydrogen or methyl group. ##STR00001##

Claims

1. A polyacrylate-silane polymer block copolymer of general structure (I): ##STR00005## wherein m and n independent of one another, are integers ranging from 2 to 4000; p is an integer ranging from 0 to 5; q is an integer ranging from 1 to 5; R.sup.1 represents hydrogen, straight-chain or branched alkyl group having 1 to 4 carbon atoms; R.sup.2 represents hydrogen, straight-chain or branched alkyl group having 1 to 18 carbon atoms; R.sup.3 represents hydrogen, hydroxyl group, straight-chain or branched alkyl group having 1 to 4 carbon atoms, or an C.sub.6-C.sub.14-aryl group; L is a single bond or a bivalent group —NH—, —C(O)NH—, —NHC(O)NH—, —OC(O)NH— or —CH.sub.2—; R.sup.4, R.sup.5 and R.sup.6 independent of one another, represent hydrogen, straight-chain or branched alkyl group having 1 to 8 carbon atoms or a polydimethylsiloxane residue; and R.sup.7 represents hydrogen or methyl group, and wherein at least one of R.sup.4, R.sup.5 and R.sup.6 represents a polydimethylsiloxane group.

2. The block copolymer as claimed in claim 1, wherein m is an integer ranging from 100 to 1000.

3. The block copolymer as claimed in claim 1, wherein n is an integer ranging from 100 to 1000.

4. The block copolymer as claimed in claim 1, wherein p is an integer ranging from 0 to 3.

5. The block copolymer as claimed in claim 1, wherein q is an integer ranging from 1 to 3.

6. The block copolymer as claimed in claim 1, wherein the weight ratio of the polyacrylate block (A) to the silane polymer block (B) is in the range of about 1:1.8×10.sup.7 to 6204:1.

7. The block copolymer as claimed in claim 1, wherein the number average molecular weight of the polydimethylsiloxane group is in the range of about 500 g/mole to about 300,000 g/mole.

8. The block copolymer as claimed in claim 1, wherein the weight ratio of the polydimethylsiloxane group to the total weight of the polyacrylate-polysilane block copolymer of general structure (I) is in the range of 1:2.8 to 1:24023.

9. The block copolymer as claimed in claim 1, wherein R.sup.1 represents hydrogen, methyl or ethyl.

10. The block copolymer as claimed in claim 1, wherein R.sup.2 represents hydrogen, methyl or ethyl.

11. The block copolymer as claimed in claim 1, wherein R.sup.3 represents hydrogen.

12. A method for preparing a polyacrylate-silane polymer block copolymer as claimed in claim 1, comprising the step of polymerizing an acrylate polymer of formula “block (A)” and a silane polymer of formula “block (B)” at a reaction temperature of at most 120° C. ##STR00006##

13. A polymer blend comprising the block copolymer as claimed in claim 1 to enhance scratch-resistance of polymers.

Description

EXAMPLES

Example 1

(1) a) Synthesis of Silane Polymer:

(2) A three-necked round bottom (RB) flask was attached with a condenser and a Schlenk line for purging with nitrogen. The RB flask was placed over a stirrer and a hot plate with heat on block. Nitrogen gas was flushed through preheated and dried RB flask to remove any moisture content prior to polymerization.

(3) About 10 grams of methacryloxypropyltrimethoxysilane was taken in the RB flask and temperature was raised to 63° C. Azobisisobutyronitrile (AIBN) (0.04 g) was added dropwise into the RB flask. The onset of the reaction is marked with increase in viscosity of the reaction mixture. The heating and stirring was continued for another 2 hours. The reaction mixture was cooled down.

(4) b) Synthesis of Acrylate Polymer:

(5) About 40 grams methyl methacrylate (MMA) along with 100 millilitres (mL) of tetrahydrofuran (THF) was taken in a three-necked RB flask which has been purged with nitrogen. The temperature of the reaction mixture was raised to 60° C. Nitrogen atmosphere was maintained through the Schlenk line. After the temperature was attained, 0.16 g of azobisisobutyronitrile (AIBN) was added to the reaction mixture. The onset of the reaction is marked by solids formation. The reaction was continued for 1 hour. A sample was withdrawn from the reaction mixture after 1 hour for further characterization. The acrylate polymer obtained from this Example was characterized using NMR. The NMR data .sup.1H NMR (400 MHz, CDCl.sub.3) δ3.7-3.5 [COOCH.sub.3], δ2.0-1.5 [C(CH.sub.3)CH.sub.2], 1.5-0.5 [C(CH.sub.3)CH.sub.2] confirms the formation of the polymer. The molecular weight analysis was performed in chloroform solvent using GPC with polystyrene standards and is listed in Table 1. The acrylate polymer has a weight average molecular weight (M.sub.w) of 209,000, a number average molecular weight (M.sub.n) of 73,000 g/mole and a polydispersity of 2.8.

(6) c) Synthesis of Block Copolymer:

(7) About 1.6 g of reaction mixture containing silane polymer of Example 1a was taken under inert atmosphere and added to the flask of Example 1b. The reaction was continued for further 1 hour and then about 10 g of polydimethylsiloxane (PDMS M.sub.n 500 g/mole) was added to the RB flask along with 0.2 g of dibutyltin dilaurate (DBTDL). The reaction was continued for further 2 hours and precipitated out in excess methanol. The resulting product was then filtered and dried in vacuum oven at 40° C. for 24 hours to remove traces of methanol from the product. The block copolymer product thus obtained was then weighed to get a yield of 89% and used for further characterisation. The block copolymer formation is confirmed by NMR from the appearance of peak at δ0.3-0.0 corresponding to [Si—CH.sub.3]. The molecular weight analysis of block copolymer was performed in chloroform solvent using GPC with polystyrene standards and is listed in Table 1. The block copolymer has a weight average molecular weight (M.sub.w) of 240,000, a number average molecular weight (M.sub.n) of 105,000 and a polydispersity of 2.3 as shown in Table 1.

(8) TABLE-US-00001 TABLE 1 GPC data of acrylate and block copolymers Example M.sub.w (g/mole) M.sub.n (g/mole) Polydispersity 1b 209,000 73,000 2.8 1c 240,000 105,000 2.3

(9) Tg of the polymer was recorded using DSC (Perkin Elmer DSC 6000) at a heating rate of 10° C./min. The block copolymer exhibits two Tg (the first Tg corresponding to PDMS appear at around 50° C. to 70° C. and the second Tg corresponding to acrylate appear between 140° C. and 150° C.

(10) The TGA (Thermogravimetric Analysis) of the block copolymer was measured using Perkin Elmer TGA 4000 to know the degradation temperature. A sample of the block copolymer was heated under nitrogen atmosphere and the heating was continued to a temperature of up to 700° C. at the rate of 20° C. per minute. The TGA of the block copolymer shows onset of degradation at a temperature of 250° C. which indicates the suitability of these block polymers in conventional polymer processing methods.

Example 2

(11) a) Synthesis of Silane Polymer

(12) About 13 g of hydroxyethylmethacrylate is taken in a RB flask and into it is added 20.5 g of 3-isocyanatopropyltrimethoxy silane. The RB flask is flushed with nitrogen and nitrogen bubbling is continued throughout the period of reaction. 0.04 g of dibutyl tin dilaurate (DBTDL) is added to the reaction mixture and temperature is raised to 65° C. The reaction is continued for about 1 hour. The completion of the reaction is marked by the disappearance of the isocyanate peak at 2270 cm.sup.−1 using Infrared (IR) spectroscopy.

(13) 10 g of reaction product is taken in a RB flask under nitrogen and 0.03 g of AIBN is added to it. The temperature is raised to 63° C. and the reaction is continued with constant heating for about two hours under nitrogen atmosphere. The reaction mixture is cooled and kept under nitrogen atmosphere till further use.

(14) b) Synthesis of Acrylate Polymer:

(15) About 30 g of MMA is taken in a RB Flask with 250 mL of THF. About 0.4 g of AIBN is added to the flask. The temperature is raised to 63° C. and heating is continued for 1 hr. The onset of polymerization is observed by solids formation in the reaction mixture.

(16) c) Synthesis of Block Copolymer

(17) The product from Example 2a is added under inert condition to the RB flask of Example 2b and the reaction is continued for one more hour. About 7.5 g of PDMS (M.sub.n 500 g/mole) along with 0.18 g of DBTDL is added to the reaction mixture and the reaction is continued for two more hours. At the end of the reaction, the block copolymer product is precipitated in excess of methanol and dried. The product can be characterized by NMR, DSC and TGA.

Example 3

(18) a) Synthesis of Silane Polymer

(19) About 10 grams of methacryloxypropyltrimethoxysilane was taken in a RB flask and temperature was raised to 63° C. About 0.04 g of AIBN was added slowly into the RB flask. The onset of the reaction was marked by increase in viscosity of the reaction mixture. The heating and stirring was continued for another 2 hours. The reaction mixture was cooled down.

(20) b) Synthesis of Acrylate Polymer

(21) Acrylic acid 7.2 g was taken in a RB Flask containing 100 ml of toluene attached to Dean stark apparatus. 1-octanol (13 g) was added to it along with 0.2 g of para toluene sulphonic acid (PTSA). The reaction mixture was refluxed. The completion of reaction was marked by the disappearance of the hydroxyl peak of 1-octanol between 3200-3400 cm.sup.−1 by IR spectroscopy. The reaction was stopped after 4 hours following the disappearance of hydroxyl peak. The reaction product was dissolved in dichloromethane and washed with water. It was dried over anydrous sodium sulphate and concentrated using rotavapor. About 20.2 g of the reaction product was taken in a RB flask under nitrogen atmosphere and heated for two hours in the presence of 0.2 g of AIBN catalyst. A small portion of the product was added to methanol which precipitated out confirming polymer formation. The product was cooled down and kept under nitrogen atmosphere.

(22) c) Synthesis of Block Copolymer

(23) To the product of Example 3b was added 2.7 g of product of Example 3a under nitrogen atmosphere. The reaction was continued for 1 hour. About 2.7 g of PDMS (M.sub.n 500 g/mole) along with 0.05 g of DBTDL was added to the reaction mixture with continued heating for 2 hours. The reaction mixture was cooled down and precipitated in excess methanol, filtered, dried and used for further characterization.