Star-shaped and triblock polymers with enhanced crosslinkability

Abstract

The present invention provides compositions comprising a) at least one polymer consisting of one polymerblock A and at least two polymerblocks B, wherein each polymerblock B is attached to the polymerblock A, and wherein at least 60 mol % of the monomer units of polymerblock B are selected from the group consisting of Formulae (1A), (1B), (1C), (1D), (1E), (1F) and 1G, 1H and 1I wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are independently and at each occurrence H or C.sub.1-10-alkyl, and b) at least one crosslinking agent carrying at least two azide groups, as well as to layers formed from these compositions, electronic devices comprising these layers and to specific polymers encompassed by the polymers of the composition. ##STR00001##

Claims

1. A composition, comprising: a) at least one polymer consisting of one polymer block A and at least two polymer blocks B; and b) at least one crosslinking agent carrying at least two azide groups wherein: each polymer block B is attached to the polymer block A, and at least 60 mol % of the monomer units of polymer block B are selected from the group consisting of: ##STR00054## ##STR00055## and R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are independently and at each occurrence H or C.sub.1-4-alkyl, wherein the weight ratio of polymer block A/total polymer blocks B is from 70/30 to 96/4 and the polymers have a number average molecular weight Mn of at least 60000 g/mol and a weight average molecular weight Mw of at least 70000 g/mol, both as determined by gel permeation chromatography, with the proviso that at least one of the monomer units (1A) and (1B) is present, and that the ratio of [mols of monomer units (1A) and (1B)]/[mols of monomer units (1A), (1B), (1C) and (1D)] is at least 30%.

2. The composition of claim 1, wherein: at least 70 mol % of the monomer units of the polymer block B are selected from the group consisting of: ##STR00056##  and R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are independently and at each occurrence H or C.sub.1-4-alkyl.

3. The composition of claim 1, wherein: at least 80 mol % of the monomer units of the polymer block B are selected from the group consisting of: ##STR00057##  and R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are H.

4. The composition of claim 1, wherein: at least 80 mol % of the monomer units of polymer block A are selected from the group consisting of: ##STR00058## R.sup.20, R.sup.21, R.sup.22, R.sup.23, R.sup.24, R.sup.25 and R.sup.26 are independently and at each occurrence selected from the group consisting of H, C.sub.6-14-aryl, 5 to 14 membered heteroaryl and C.sub.1-30-alkyl; R.sup.a is C(O)OH, C(O)OC.sub.1-30-alkyl, C(O)—H, C(O)C.sub.6-14-aryl, C(O)N(C.sub.1-30-alkyl).sub.2, C(O)N(C.sub.6-14-aryl).sub.2, C(O)N(C.sub.1-30-alkyl)(C.sub.6-14-aryl), C(O)—C.sub.6-14-aryl, C(O)—C.sub.1-30-alkyl, O—C.sub.6-14-aryl, O—C.sub.1-30-alkyl, OC(O)C.sub.1-30-alkyl, OC(O)C.sub.6-14-aryl or CN; C.sub.6-14-aryl and 5-14 membered heteroaryl can be substituted with one or more substituents selected from the group consisting of C.sub.1-10-alkyl, C(O)OH, C(O)OC.sub.1-10-alkyl, C(O)phenyl, C(O)N(C.sub.1-10-alkyl).sub.2, C(O)N(phenyl).sub.2, C(O)N(C.sub.1-10-alkyl)(phenyl), C(O)-phenyl, C(O)—C.sub.1-10-alkyl, OH, O-phenyl, O—C.sub.1-10-alkyl, OC(O)C.sub.1-10-alkyl, OC(O)-phenyl and CN and NO.sub.2; C.sub.1-30-alkyl can be substituted with one or more substituents selected from the group consisting of with phenyl, C(O)OH, C(O)OC.sub.1-10-alkyl, C(O)phenyl, C(O)N(C.sub.1-10-alkyl).sub.2, C(O)N(phenyl).sub.2, C(O)N(C.sub.1-10-alkyl)(phenyl), C(O)-phenyl, C(O)—C.sub.1-10-alkyl, O-phenyl, O—C.sub.1-10-alkyl, OC(O)C.sub.1-10-alkyl, OC(O)-phenyl, Si(C.sub.1-10-alkyl).sub.3, Si(phenyl).sub.3 and CN and NO.sub.2; n is an integer from 1 to 3; and L.sup.20 is C.sub.1-10-alkylene, C.sub.2-10-alkenylene, C.sub.2-10-alkynylene, C.sub.6-14-arylene or S(O).

5. The composition according to claim 1, wherein: at least 80 mol % of the monomer units of polymer block A are selected from the group consisting of: ##STR00059## R.sup.20, R.sup.21 and R.sup.22 are independently selected from the group consisting of H, C.sub.6-14-aryl, 5 to 14 membered heteroaryl and C.sub.1-30-alkyl; R.sup.a is C(O)OC.sub.1-30-alkyl; C.sub.6-14-aryl and 5-14 membered heteroaryl can be substituted with one or more C.sub.1-10-alkyl; C.sub.1-30-alkyl can be substituted with one or more substituents selected from the group consisting of Si(C.sub.1-10-alkyl).sub.3 and Si(phenyl).sub.3; n is an integer from 1 to 3; and L.sup.20 is C.sub.1-10-alkylene or C.sub.6-14-arylene.

6. The composition of claim 1, wherein: at least 90 mol % of the monomer units of polymer block A is a monomer unit selected from the group consisting of: ##STR00060## R.sup.20 and R.sup.21 are independently selected from the group consisting of H and C.sub.6-14-aryl; C.sub.6-14-aryl can be substituted with one or more C.sub.1-10-alkyl; and L.sup.20 is C.sub.6-14-arylene.

7. The composition of claim 1, wherein: the crosslinking agent carrying at least two azide groups is of formula: ##STR00061## a is 0 or 1; R.sup.50 is at each occurrence selected from the group consisting of H, halogen, SO.sub.3M and C.sub.1-20-alkyl, which C.sub.1-20-alkyl can be substituted with one or more halogen, wherein M is H, Na, K or Li; and L.sup.50 is a linking group.

8. The composition of claim 7, wherein: L.sup.50 is a linking group of formula: ##STR00062## b, c, d, e, f, g and h are independently from each other 0 or 1, provided that b, c, d, e, f, g and h are not all at the same time 0; W.sup.1, W.sup.2, W.sup.3 and W.sup.4 are independently selected from the group consisting of C(O), C(O)O, C(O)—NR.sup.51, SO.sub.2—NR.sup.51, NR.sup.51, N.sup.+R.sup.51R.sup.51, CR.sup.51═CR.sup.51 and ethynylene; R.sup.51 is at each occurrence H or C.sub.1-10-alkyl, or two R.sup.51 groups, which can be from different W.sup.1, W.sup.2, W.sub.3 and W.sup.4 groups, together with the connecting atoms form a 5, 6 or 7 membered ring, which may be substituted with one to three C.sub.1-6-alkyl; Z.sup.1, Z.sup.2 and Z.sup.3 are independently selected from the group consisting of C.sub.1-10-alkylene, C.sub.5-8-cycloalkylene, C.sub.6-14-arylene, 5 to 14 membered heteroarylene, and polycyclic system containing at least one ring selected from C.sub.6-14-aromatic ring and 5 to 14 membered heteroaromatic ring; and C.sub.1-10-alkylene, C.sub.5-8-cycloalkylene, C.sub.6-14 membered arylene, 5 to 14 membered heteroarylene and polycyclic system containing at least one ring selected from C.sub.6-14-aromatic ring and 5 to 14 membered heteroaromatic ring substituted with one to five C.sub.1-20-alkyl or phenyl.

9. The composition of claim 1, further comprising a solvent.

10. The composition of claim 8, wherein the composition is a solution and comprises; i) 0.1 to 500 mg of the at least one polymer based on 1000 mg of the composition; ii) 0.1 to 20% by weight of the at least one crosslinking agent carrying at least two azide groups based on the weight of the one or more polymers; and iii) a solvent.

11. A cured layer formed from the composition of claim 1.

12. An electronic device, comprising the cured layer of claim 11.

13. The electronic device of claim 12, wherein: the electronic device is an organic field effect transistor; and the layer is the dielectric layer.

Description

(1) FIG. 1 shows the drain current I.sub.ds in relation to the gate voltage V.sub.gs (transfer curve) for the top-gate field effect transistor at a source voltage V.sub.ds of −5V (triangle), respectively, −30V (square) for the a top-gate field effect transistor comprising a dielectric layer formed from polymer Pa.

(2) FIG. 2 shows the drain current I.sub.ds in relation to the gate voltage V.sub.gs (transfer curve) for the top-gate field effect transistor at a source voltage V.sub.ds of −5V (triangle), respectively, −30V (square) for the a top-gate field effect transistor comprising a dielectric layer formed from polymer Pb.

(3) FIG. 3 shows the drain current I.sub.ds in relation to the gate voltage V.sub.gs (transfer curve) for the top-gate field effect transistor at a source voltage V.sub.ds of −5V (triangle), respectively, −30V (square) for the a top-gate field effect transistor comprising a dielectric layer formed from polymer Pc.

(4) FIG. 4 shows the drain current I.sub.ds in relation to the gate voltage V.sub.gs (transfer curve) for the top-gate field effect transistor at a source voltage V.sub.ds of −5V (triangle), respectively, −30V (square) for the a top-gate field effect transistor comprising a dielectric layer formed from polymer Pd.

EXAMPLES

Example 1

(5) Preparation of a star-shaped polymer Pa having a styrene based-inner block and butadiene-based outer blocks

(6) First Step: Preparation of a Multifunctional Initiator Oligomer

(7) In a 10 L stainless steel reactor equipped with a cross-bar stirrer, 2244 mL cyclohexane and 223.1 g (1239 mmol) 1,1-diphenylethylene (DPE) were heated to 60° C. and titrated with s-BuLi (1.4 M in cyclohexane) until a stable orange-red color remained. Then, 13.4 ml (18.76 mmol) s-BuLi (1.4 M in cyclohexane) was added to the reaction mixture and the reaction mixture was stirred for 30 min. Then, 2.94 mL (18.62 mmol) divinylbenzene (80%, Aldrich technical grade) was added to the reaction mixture and the reaction mixture was stirred for 10 min. Then 10 mL (87 mmol) styrene was added and the reaction mixture was stirred for further 10 min.

(8) Second Step: Preparation of a Star-Shaped Polymer from the Multifunctional Initiator Oligomer

(9) 310.8 g (2988 mmol) styrene was added to the reaction mixture of the first step and the reaction mixture was stirred for 30 min. Then, 103.6 g (996 mmol) styrene were added and the reaction mixture was stirred for further 30 min. 172 mL (112.5 g, 2009 mmol) butadiene was added to the reaction mixture and the reaction mixture was stirred at 70° C. for 30 min. The reaction mixture was quenched with 1.5 mL isopropanol and acidified with 1.5 mL acetic acid. To the colorless reaction mixture 1500 mL toluene was added and then cyclohexane was removed at the rotavap. The remaining reaction mixture was decanted from some gel particles, filtered over a G4 fritte and then precipitated into isopropanol while stirring with a Ultraturrax. The white precipitate was filtered off and washed 10 times with 300 mL isopropanol each. The polymer was then re-dissolved in 500 mL dry toluene and filtered over a 29 mm column filled with a layer of 15 cm dried silicagel and 5 cm kieselgur, followed by washing of the column with toluene until the wash-solution was polymer-free. The combined solutions were concentrated at the rotavap to 600 mL and precipitated into 6000 mL isopropanol while stirring with an Ultraturrax, the white precipitate was filtrated and washed 10 times with 300 isopropanol each and finally dried at 90° C. under vacuum. The polymer Pa was obtained as white powder. Mn=76000 g/mol. Mw=152000 g/mol (as determined by gel-permeation chromatography with polystyrene standards). PDI 2.0. Tg=−102 and 125° C. Amount of 1,2-addition of butadiene in the polybutadiene blocks=9% and amount of 1,4-addition of butadiene in the polybutadiene blocks=91% (as determined by .sup.1H-NMR) based on the total amount of butadiene in the polybutadiene block.

Example 2

(10) Preparation of triblock polymer Pb comprising a styrene-based inner block and butadiene-based outer blocks with a mass ratio styrene:butadiene of 90:10 and an amount of 1,2-addition of butadiene in the polybutadiene blocks of 73% based on the total amount of butadiene in the polybutadiene block

(11) In a 10 L stainless steel reactor equipped with a cross-bar stirrer, 4872 ml (3800 g) cyclohexane, 256 mL (200 g) THF and 1 g 1,1-diphenylethylene (DPE) were heated to 30° C. and titrated with s-BuLi (1.4 M in cyclohexane) until a stable orange-red color remained (ca. 1.8 ml). Then, 7.14 mL s-BuLi (1.4 M in cyclohexane) was added to the reaction mixture and immediately 76 mL (50 g) butadiene were added under stirring. The temperature was kept at 60° C. controlled by the reactor jacket temperature after 20 min 990 mL (900 g) styrene was added slowly to keep the temperature at 50° C. by jacket counter-cooling. After 25 min another 76 mL (50 g) butadiene were added. After 20 min 1.15 mL isopropanol was added and further stirred for 10 min. The colorless solution was transferred into two 5 Liter canisters and shaken together with 25 mL water and 50 g dry ice each for purpose of acidification.

(12) Workup

(13) The acidified mixture (solid content 20%) was precipitated into ethanol (10 fold volume containing 0.1% Kerobit TBK with respect to polymer), washed 3 times with 5 L ethanol and 3 times with 1 L distilled water on a Büchi funnel. Finally, the white powder was washed two times with 2.5 L ethanol and four times with 250 mL ethanol and finally dried at 50° C. under vacuum for 24 h. The obtained white powder, triblock polymer Pc, had the following characteristics: Mn=220000 g/mol. Mw=330000 g/mol (as determined by gel-permeation chromatography with polystyrene standards). PDI 1.5. Amount of 1,2-addition of butadiene in the polybutadiene blocks=73% (as determined by .sup.1H-NMR) based on the total amount of butadiene in the polybutadiene block.

Example 3

(14) Preparation of triblock polymer Pc comprising a styrene-based inner block and butadiene-based outer blocks with a mass ratio styrene:butadiene of 85:15 and an amount of 1,2-addition of butadiene in the polybutadiene blocks of 73% based on the total amount of butadiene in the polybutadiene block

(15) In a 10 L stainless steel reactor equipped with a cross-bar stirrer, 4872 mL (3800 g) cyclohexane, 256 ml (200 g) THF and 1 g 1,1-diphenylethylene (DPE) were heated to 30° C. and titrated with s-BuLi (1.4 M in cyclohexane) until a stable orange-red color remained (ca. 1.8 mL). Then, 7.14 mL s-BuLi (1.4 M in cyclohexane) was added to the reaction mixture and immediately 115 mL (75 g) butadiene were added under stirring. The temperature was kept at 60° C. controlled by the reactor jacket temperature after 20 min 935 mL (850 g) styrene was added slowly to keep the temperature at 50° C. by jacket counter-cooling. After 25 min another 115 mL (75 g) butadiene were added. After 20 min 1.15 mL isopropanol was added and further stirred for 10 min. The colorless solution was transferred into two 5 L canisters and shaken together with 25 mL water and 50 g dry ice each for purpose of acidification.

(16) Workup

(17) The acidified mixture (solid content 20%) was precipitated into ethanol (10 fold volume containing 0.1% Kerobit TBK with respect to polymer), washed 3 times with 5 L ethanol and 3 times with 1 L distilled water on a Büchi funnel. Finally, the white powder was washed two times with 2.5 L ethanol and four times with 250 mL ethanol and finally dried at 50° C. under vacuum for 24 h. The obtained white powder, triblock polymer Pc, had the following characteristics: Mn=140000 g/mol. Mw=170000 g/mol. PDI 1.2. Amount of 1,2-addition of butadiene in the polybutadiene blocks=73% (as determined by .sup.1H-NMR) based on the total amount of butadiene in the polybutadiene block.

Example 4

(18) Preparation of triblock polymer Pd comprising a styrene-based inner block and butadiene-based outer blocks with a mass ratio styrene:butadiene of 80:20 and an amount of 1,2-addition of butadiene in the polybutadiene blocks of 73% based on the total amount of butadiene in the polybutadiene block

(19) In a 10 L stainless steel reactor equipped with a cross-bar stirrer, 4872 mL (3800 g) cyclohexane, 256 mL (200 g) THF and 1 g 1,1-diphenylethylene (DPE) were heated to 30° C. and titrated with s-BuLi (1.4 M in cyclohexane) until a stable orange-red color remained (ca. 1.8 mL). Then, 7.14 mL s-BuLi (1.4 M in cyclohexane) was added to the reaction mixture and immediately 153 mL (100 g) butadiene were added under stirring. The temperature was kept at 60° C. controlled by the reactor jacket temperature after 20 min 880 mL (800 g) styrene was added slowly to keep the temperature at 50° C. by jacket counter-cooling. After 25 min another 153 mL (100 butadiene were added. After 20 min 1.15 mL isopropanol was added and further stirred for 10 min. The colorless solution was transferred into two 5 L canisters and shaken together with 25 mL water and 50 g dry ice each for purpose of acidification.

(20) Workup

(21) The acidified mixture (solid content 20%) was precipitated into ethanol (10 fold volume containing 0.1% Kerobit TBK with respect to polymer), washed 3 times with 5 L ethanol and 3 times with 1 L distilled water on a Büchi funnel. Finally, the white powder was washed two times with 2.5 L ethanol and four times with 250 ml ethanol and finally dried at 50° C. under vacuum for 24 h. The obtained white powder, triblock polymer Pd, had the following characteristics: Mn=68000 g/mol. Mw=78000 g/mol. PDI 1.15. Amount of 1,2-addition of butadiene in the polybutadiene blocks=73% (as determined by .sup.1H-NMR) based on the total amount of butadiene in the polybutadiene block.

Example 5

(22) Preparation of top-gate field effect transistors comprising a dielectric layer formed from polymer Pa of example 1, polymer Pb of example 2, polymer Pc of example 3, respectively, polymer Pd of example 4 in the presence of a crosslinker

(23) Gold was sputtered onto PET substrate to form approximately 40 nm thick gold source/drain electrodes. A 0.75% (weight/weight) solution of the diketopyrrolopyrrole semiconducting polymer of example 1 of WO 2013/083506 in toluene was filtered through a 0.45 micrometer polytetrafluoroethylene (PTFE) filter and then applied by spin coating (1,000 rpm, 30 seconds). The wet organic semiconducting layer was dried at 90° C. on a hot plate for 60 seconds. A solution of 80 mg/ml of polymer Pa, prepared as described in example 1, in mixture of propylene glycol monomethyl ether acetate (PGMEA) and cyclopentanone (CP) (70/30), containing 4% by weight of 2,7-bis[2-(4-azido-2,3,5,6-tetrafluoro-phenyl)ethynyl]-9,9-dihexyl-fluorene as crosslinker based on the weight of polymer Pa, was filtered through a 1 micrometer filter. The solution was spin-coated (1800 rpm, 30 seconds) on the semiconducting layer. The wet dielectric layer was pre-baked at 90° C. for 2 minutes and subsequently UV-cured by irradiating at 365 nm with a dosage of ˜100 mJ/cm.sup.2 under ambient conditions. Afterwards, the device was wetted with a solution of PGMEA/CP (70/30) for 1 minute to develop the dielectric and spin-coated dry at (2000 rpm, 1 min) followed by a post-bake of 15 minutes at 90° C. on a hot plate. Gate electrodes of gold (thickness approximately 80 nm) were evaporated through a shadow mask on the dielectric layer.

(24) The same procedure as described for polymer Pa was used when preparing a top-gate field effect transistor using polymer Pb as dielectric, but 3% instead of 4% by weight of 2,7-bis[2-(4-azido-2,3,5,6-tetrafluoro-phenyl)ethynyl]-9,9-dihexyl-fluorene as crosslinker based on the weight of polymer Pb was used.

(25) The same procedure as described for polymer Pa was used when preparing a top-gate field effect transistor using polymer Pc as dielectric.

(26) The same procedure as described for polymer Pa was used when preparing a top-gate field effect transistor using polymer Pd as dielectric, but 6% instead of 4% by weight of 2,7-bis[2-(4-azido-2,3,5,6-tetrafluoro-phenyl)ethynyl]-9,9-dihexyl-fluorene as crosslinker based on the weight of polymer Pd was used.

(27) The top gate field effect transistors were measured by using a Keithley 4200-SCS semiconductor characterization system.

(28) The drain current I.sub.ds in relation to the gate voltage V.sub.gs (transfer curve) for the top-gate field effect transistor at a source voltage V.sub.ds of −5V (triangle), respectively, −30V (square) for the a top-gate, bottom-contact field effect transistor comprising a dielectric layer formed from polymer Pa is shown in FIG. 1.

(29) The drain current I.sub.ds in relation to the gate voltage V.sub.gs (transfer curve) for the top-gate field effect transistor at a source voltage V.sub.ds of −5V (triangle), respectively, −30V (square) for the a top-gate, bottom-contact field effect transistor comprising a dielectric layer formed from polymer Pb is shown in FIG. 2.

(30) The drain current I.sub.ds in relation to the gate voltage V.sub.gs (transfer curve) for the top-gate field effect transistor at a source voltage V.sub.ds of −5V (triangle), respectively, −30V (square) for the a top-gate, bottom-contact field effect transistor comprising a dielectric layer formed from polymer Pc is shown in FIG. 3.

(31) The drain current I.sub.ds in relation to the gate voltage V.sub.gs (transfer curve) for the top-gate field effect transistor at a source voltage V.sub.ds of −5V (triangle), respectively, −30V (square) for the a top-gate, bottom-contact field effect transistor comprising a dielectric layer formed from polymer Pd is shown in FIG. 4.

(32) The charge-carrier mobility was extracted in the saturation regime from the slope of the square root drain current I.sub.ds.sup.1/2 versus gate-source voltage V.sub.gs. The threshold voltage V.sub.on was obtained using the following equation: μ=2 I.sub.ds/{(W/L)Ci (V.sub.gs−V.sub.on).sup.2}, wherein Ci is the capacitance per unit of the dielectric layer, and W/L is the ratio between the transistor width and length (W/L=25). The thickness of the dielectric has been measured by a profilometer to 360 nm for Pa and Pb, to 565 nm for polymer Pc, and to 365 nm for polymer Pd.

(33) The average values of the charge carrier mobility μ, the I.sub.on/I.sub.off ratio and the onset voltage V.sub.on for the organic field effect transistors are given in table 1.

(34) TABLE-US-00001 TABLE 1 styrene: cross- charge carrier Ig @ poly- butadiene linker mobility V.sub.on −30 V mer [g:g] [%].sup.a [cm.sup.2/Vs] I.sub.on/I.sub.off [V] [A] Pa 80:20 4 0.41 4E+05 −1.5 5E−08 Pb 90:10 3 0.44 2E+05 −0.5 1E−07 Pc 85:15 4 0.38 5E+04 −3.0 2E−08 Pd 80:20 6 0.34 5E+04 −2.0 8E−08 .sup.aweight crosslinker based on the weight of polymer [%]

Example 6 (Comparative)

(35) Preparation of random polymer CP1 comprising a styrene and butadiene units with a mass ratio styrene:butadiene of 90:10 and an amount of 1,2-addition of butadiene of 15% based on the total amount of butadiene units

(36) In a 10 L stainless steel reactor equipped with a cross-bar stirrer, 5128 ml (4000 g) cyclohexane and 1 g 1,1-diphenylethylene (DPE) were heated to 60° C. and titrated with s-BuLi (1.4 M in cyclohexane) until a stable orange-red color remained (ca. 1.6 mL). Then, 7.14 mL s-BuLi (1.4 M in cyclohexane) and 1.61 mL potassium tert. amylate (0.177 M in cyclohexane) was added to the reaction mixture and immediately 990 mL (900 g) styrene and 153 mL butadiene (100 g) were added at the same time over a period of 60 min. The temperature was kept at 75° C. by counter-cooling of the reactor jacket. Then the reaction mixture was stirred for 30 min followed by the addition of 1.15 mL isopropanol and further stirring for 10 min. The colorless solution was transferred into two 5 L canisters and shaken together with 25 mL water and 50 g dry ice each for purpose of acidification.

(37) Workup

(38) The acidified mixture (solid content 20%) was precipitated into ethanol (10 fold volume containing 0.1% Kerobit TBK with respect to polymer), washed 3 times with 5 L ethanol and 3 times with 1 L distilled water on a Büchi funnel. Finally, the white powder was washed two times with 2.5 L ethanol and four times with 250 mL ethanol and finally dried at 50° C. under vacuum for 24 h. The obtained white powder, polymer CP1, had the following characteristics. Mn=111000 g/mol. Mw=117000 g/mol. PDI 1.05. The mass ratio of styrene and butadiene was 90:10 and the amount of 1,2-addition of butadiene was 15% based on the total amount of butadiene units (as determined by 1H-NMR). Tg (DSC): one transition at 72.8° C.

Example 7 (Comparative)

(39) Preparation of multiblock polymer CP2 comprising a styrene and butadiene units with a mass ratio styrene:butadiene of 90:10 and an amount of 1,2-addition of butadiene of 24% based on the total amount of butadiene units

(40) In a 10 L stainless steel reactor equipped with a cross-bar stirrer, 5128 ml (4000 g) cyclohexane and 1 g 1,1-diphenylethylene (DPE) were heated to 60° C. and titrated with s-BuLi (1.4 M in cyclohexane) until a stable orange-red color remained (ca. 1.6 mL). Then, 7.14 mL s-BuLi (1.4 M in cyclohexane) was added to the reaction mixture and immediately 99 ml (90 g) styrene and 15.3 mL butadiene (10 g) were added at the same time under stirring. The temperature was kept at 70° C. controlled by the reactor jacket temperature for 10 min. Then the procedure was repeated further nine times followed by the addition of 1.15 mL isopropanol and further stirring for 10 min. The colorless solution was transferred into two 5 L canisters and shaken together with 25 mL water and 50 g dry ice each for purpose of acidification.

(41) Workup

(42) The acidified mixture (solid content 20%) was precipitated into ethanol (10 fold volume containing 0.1% Kerobit with respect to polymer), washed 3 times with 5 L ethanol and 3 times with 1 L distilled water on a Büchi funnel. Finally, the white powder was washed two times with 2.5 L ethanol and four times with 250 mL ethanol and finally dried at 50° C. under vacuum for 24 h. The obtained white powder, polymer CP2, had the following characteristics: Mn=90000 g/mol. Mw=110000 g/mol. PDI 1.22. The mass ratio of styrene and butadiene was 90:10 and the amount of 1,2-addition of butadiene was 24% based on the total amount of butadiene units (as determined by 1H-NMR). Tg (DSC): one transition at 69.9° C.

Example 8 (Comparative)

(43) Preparation of random polymer CP3 comprising styrene and butadiene units with a mass ratio styrene:butadiene of 90:10 and an amount of 1,2-addition of butadiene of 72% based on the total amount of butadiene units

(44) In a 10 L stainless steel reactor equipped with a cross-bar stirrer, 4872 mL (3800 g) cyclohexane, 256 mL (200 g) THF and 1 g 1,1-diphenylethylene (DPE) were heated to 30° C. and titrated with s-BuLi (1.4 M in cyclohexane) until a stable orange-red color remained (ca. 1.8 mL). Then, 7.14 mL s-BuLi (1.4 M in cyclohexane) was added to the reaction mixture and immediately 990 mL (900 g) styrene and 153 mL butadiene (100 g) were added at the same time over a period of 60 min. The temperature was kept at 50° C. by counter-cooling of the reactor jacket. Then, the reaction mixture was stirred for 15 min followed by the addition of 1.15 ml isopropanol and further stirring for 10 min. The colorless solution was transferred into two 5 L canisters and shaken together with 25 ml water and 50 g dry ice each for purpose of acidification.

(45) Workup

(46) The acidified mixture (solid content 20%) was precipitated into ethanol (10 fold volume containing 0.1% Kerobit TBK with respect to polymer), washed 3 times with 5 L ethanol and 3 times with 1 L distilled water on a Büchi funnel. Finally, the white powder was washed two times with 2.5 L ethanol and four times with 250 mL ethanol and finally dried at 50° C. under vacuum for 24 h. The obtained white powder, polymer CP3, had the following characteristics: Mn=206000 g/mol. Mw=230000 g/mol. PDI 1.11. The mass ratio of styrene and butadiene was 90:10 and the amount of 1,2-addition of butadiene was 72% based on the total amount of butadiene units (as determined by 1H-NMR).

Example 9

(47) Evaluation of the effect of the radiation on the retention of polymer layers formed from polymers Pa, Pb, Pc, Pd, CP1, CP2, CP3 and polystyrene (PS) and crosslinking agent carrying two azide groups

(48) A solution of 80 mg/mL of polymer Pa prepared as described in example 1 in mixture of propylene glycol monomethyl ether acetate (PGMEA) and cyclopentanone (CP) (70/30) containing 4% by weight of 2,7-bis[2-(4-azido-2,3,5,6-tetrafluoro-phenyl)ethynyl]-9,9-dihexyl-fluorene as crosslinker based on the weight of polymer was filtered through a 1 micrometer filter and applied on a silicon dioxide substrate by spin coating (1800 rpm, 30 seconds). The wet dielectric layer was pre-baked at 90° C. for 2 minutes on a hot plate to obtain a 400 nm thick layer. The polymer dielectric layer was UV-cured using 365 nm (dose of 100 mJ/cm.sup.2) under ambient conditions.

(49) The same procedure for the preparation of a polymer dielectric layer as described for polymer Pa above was repeated using polymer Pb prepared as described in example 2, but using 3% instead of 4% by weight of 2,7-bis[2-(4-azido-2,3,5,6-tetrafluoro-phenyl)ethynyl]-9,9-dihexyl-fluorene as crosslinker based on the weight of polymer Pb.

(50) The same procedure for the preparation of a polymer dielectric layer as described for polymer Pa above was repeated using polymer Pc prepared as described in example 3, and polystyrene (PS) from Sigma-Aldrich having a molecular weight Mw of 192000 g/mol.

(51) The same procedure for the preparation of a polymer dielectric layer as described for polymer Pa above was repeated using polymer Pd prepared as described in example 4, but using 6% instead of 4% by weight of 2,7-bis[2-(4-azido-2,3,5,6-tetrafluoro-phenyl)ethynyl]-9,9-dihexyl-fluorene as crosslinker based on the weight of polymer Pd.

(52) The same procedure for the preparation of a polymer dielectric layer as described for polymer Pa above was repeated for comparative polymer CP1 prepared as described in example 6, for comparative polymer CP2 prepared as described in example 7, and for comparative polymer CP3 prepared as described in example 8.

(53) Development of the dielectric layers was done by immersing the dielectric layers into a mixture of propylene glycol monomethyl ether acetate (PGMEA) and cyclopentanone (CP) (70/30) for 1 minute followed by heating at 90° C. for 5 minutes. The thickness of the dielectric layer was measured after curing before development (d1) and after development (d2) using Veeco Dektak 150 to obtain the film retention ratio (d2/d1). The film retention ratios (d2/d1) were determined. The results are shown in table 2.

(54) TABLE-US-00002 TABLE 2 1,2- styrene: cross- Mn Mw addition d2/ Poly- butadiene linker polymer [g/ [g/ butadiene d1 mer [g:g] [%].sup.a type mol] mol] [%] [%] Pa 80:20 4 star-shaped 76000 152000 9 80 Pb 90:10 3 triblock 220000 330000 73 81 Pc 85:15 4 triblock 140000 170000 73 85 Pd 80:20 6 triblock 68000 78000 73 70 CP1 90:10 4 random 111000 117000 15 39 CP2 90:10 4 multiblock 90000 110000 24 52 CP3 90:10 4 random 206000 230000 72 58 PS 100:0  4 homo n.a. 192000 — 0 .sup.aweight crosslinker based on the weight of polymer [%]

(55) Table 2 shows that the film retention ratio of crosslinked polymers Pa, Pb, Pc and Pd is considerably higher than those of crosslinked comparative polymers CP1, CP2 and CP3, and that polystyrene (PS) does not crosslink at all when UV-treated using 365 nm (dose of 100 mJ/cm.sup.2) under ambient conditions. All crosslinking reactions were performed under ambient conditions.