EP3554992A1

EP3554992A1 - Nanostructured block copolymer film comprising an amorphous block

Info

Publication number: EP3554992A1
Application number: EP17822414.3A
Authority: EP
Inventors: Christophe Navarro; Didier Bourissou; Blanca Martin-Vaca; Franck KAYSER
Original assignee: Centre National de la Recherche Scientifique CNRS; Arkema France SA; Universite Toulouse III Paul Sabatier
Current assignee: Centre National de la Recherche Scientifique CNRS; Arkema France SA; Universite Toulouse III Paul Sabatier
Priority date: 2016-12-14
Filing date: 2017-12-13
Publication date: 2019-10-23
Also published as: US20200079912A1; TW201831553A; WO2018109388A1; FR3060008A1; JP2020513465A; TWI668246B; KR20190097010A; CN110267910A

Abstract

The invention relates to a block copolymer film nanostructured into nanodomains, said copolymer comprising at least a first biodegradable block and a second block that is chemically different from the first block. The block copolymer is characterised in that the first biodegradable block is amorphous, and in that the second block originates from an oligomer or a polymer bearing a hydroxy function at at least one end and acts as a macroinitiator for the polymerisation of the first block.

Description

NANOSTRUCTURE BLOCK COPOLYMER FILM COMPRISING A

AMORPHOUS BLOCK

[Field of the invention!

The present invention relates to the field of nanostructured block copolymers having nano-domains oriented in a particular direction.

More particularly, the invention relates to a block copolymer film comprising at least one amorphous block, capable of being easily removed after structuring, and having a high phase segregation, with a low Lo period, preferably less at 20nm.

By period, noted Lo in the following description, means the minimum distance separating two neighboring domains of the same chemical composition, separated by a different chemical composition area.

[Prior Art] [0004] The development of nanotechnologies has made it possible to constantly miniaturize products in the field of microelectronics and microelectromechanical systems (MEMS) in particular. Today, conventional lithography techniques no longer meet these needs for miniaturization, because they do not allow to achieve structures with dimensions less than 60nm.

It was therefore necessary to adapt the lithography techniques and create engraving masks that can create smaller and smaller patterns with high resolution. With block copolymers it is possible to structure the arrangement of the constituent blocks of the copolymers, by phase segregation between the blocks thus forming nano-domains, at scales of less than 50 nm. Because of this ability to nanostructure, the use of block copolymers in the fields of electronics or optoelectronics is now well known.

Among the nano-lithography masks, the most studied block copolymer films so far are the films based on Polystyrene-i-poly (methylmethacrylate), noted below PS-b-PMMA . Thus, in the document entitled "Directed self-assembly of block copolymers for nanolithography: manufacturing of isolated features and essential integrated circuit geometries", ACSNano 2007, 1, 168, MP Stoykovich et al. describe advanced lithography processes based on the self-assembly of block copolymers and using PS-b-PMMA (polystyrene-b-poly (methylmethacrylate) masks.) To use a block copolymer film as a mask For etching, a block of the copolymer must be selectively removed to create a porous film of the residual block, the patterns of which can be subsequently transferred by etching to an underlying layer. With respect to the PS-b-PMMA film, PMMA (Poly (methyl methacrylate)) is usually selectively removed to create a residual PS (Polystyrene) mask. To create such masks, the nano-domains must be oriented perpendicular to the surface of the underlying layer. Such a structuring of the domains requires particular conditions such as the preparation of the surface of the underlying layer, but also the composition of the block copolymer. An important factor is the phase segregation factor, also referred to as the Flory-Huggins interaction parameter and denoted "χ". This parameter makes it possible to control the size of the nano domains. More particularly, it defines the tendency of blocks of the block copolymer to separate into nano-domains. Thus, the product χΝ, the Flory-Huggins parameter χ and the degree of polymerization N give an indication of the compatibility of two blocks and whether they can separate at a given temperature. For example, a diblock copolymer of strictly symmetrical composition separates into micro-domains if the product χΝ is greater than 10.49. If this product χΝ is less than 10.49, the blocks mix and the phase separation is not observed at the observation temperature.

Due to the constant need for miniaturization, it is generally sought to increase this degree of phase separation, in order to produce nano-lithography masks making it possible to obtain very high resolutions, typically less than 20 nm, and preferably less than 15 nm, while maintaining certain basic properties of the block copolymer, such as a good temperature resistance of the block copolymer, or a depolymerization of PMMA under UV treatment when the block copolymer is a PS-b-PMMA , etc.

[0008] In Macromolecules, 2008, 41, 9948, Y. Zhao et al. Estimated the Flory-Huggins parameter for a PS-b-PMMA block copolymer. The parameter of Flory-Huggins x obeys the following relation: χ = a + b / T, where the values a and b are constant specific values depending on the nature of the blocks of the copolymer and T is the temperature of the heat treatment applied to the block copolymer to allow it to organize itself, that is to say to obtain a phase separation of the domains, an orientation of the domains and a reduction of the number of defects. More particularly, the values a and b respectively represent the entropic and enthalpic contributions. Thus, for a PS-b-PMMA block copolymer, the phase segregation factor obeys the following relationship: χ = 0.0282 + 4.46 / T.

This low value of the Flory-Huggins interaction parameter χ (0.04 to 298K) therefore limits the interest of block copolymers based on PS and PMMA, for producing structures with very high resolutions.

To overcome this problem, MD Rodwing et al., In the article entitled "Polylactide-Poly (dimethylsiloxane) -Polylactide triblock copolymers as multifuntional materials for nanolithographic application", ACSNano 2010, 4, 725, have shown that the the chemical nature of the two blocks of the copolymer can be changed to increase the Flory-Huggins parameter χ and to obtain a desired morphology with periodicities less than 20 nm. Such results have, for example, been obtained with poly (lactic acid -b-dimethylsiloxane-1-lactic acid) PLA-b-PDMS-6-PLA copolymers.

[001 1] However, it has also been demonstrated by H. Takahashi et al, in the article entitled "Defectivity in laterally confined lamella-forming diblock copolymers: thermodynamic and kinetic aspects", Macromolecules 2012, 45, 6253, that There is an influence of the Flory-Huggins parameter χ on the kinetics of segregation and thus on the kinetics of decrease of defects. A high value of the Flory-Huggins parameter χ results in a slowing down of the segregation kinetics leading to the appearance of the defects at the time of the organization of the domains.

The research has therefore turned to other block copolymers, especially to block copolymers associating blocks of polyester type blocks of different nature, polyether type or polyolefin for example. The development of selective polymerization methods, controlled and alive, allowed the preparation of block copolymers with blocks of various chemical natures and a well-defined structure. In some of these polymers, the blocks exhibit poor compatibility, resulting in segregation leading to nano-structuring. The chemical nature of the blocks studied is very diverse and, in recent years, an increased interest has been brought to the incorporation of a biodegradable block, in particular of polyester type, which can be eliminated easily. after nano-structuring. PLA (poly lactic acid) and to a lesser extent PCL (polycaprolactone) are the most studied polyesters in this context, especially in combination with PS (polystyrene), PDMS (polydimethylsiloxane) or PTMSS (polytrimethylsilylstyrene) blocks. ). Thus, the document entitled "Ordered Nanoporous Polymers from Polystyrene-Polylactide Block Copolymers", AS Zalusky et al, J.AM. CHEM. SOC. 2002, 124, 12761 -12773 and the document entitled "Thin Film Self-Assembly of Poly (trimethylsilylstyrene-1-D, L-lactide) with Sub-10nm Domains", JD Cushen et al, Macromolecules, 2012, 45, 8722- 8728, respectively describe the preparation of diblock copolymers of PS-b-PLA and diblock copolymers of PTMSS-i -PLA having nano-domains of sizes less than 10 nm and whose period is between 12 and 15 nm. Finally, the document entitled "High χ-low N Block Polymers: How Far Can We Go ?," C. Sinturel et al., ACS Macro Letters, 2015, 4, 1044-1050, describes block copolymers associating PLA with PS. , PDMS or PTMSS and highlights the fact that a low molecular weight block copolymer, typically less than 20000 g / mol, allows structuring in nano-domains of sizes less than 10 nm and with a period Lo less than 20 nm.

The Applicant has been particularly interested in polyesters polylactones type. The ring-opening polymerization of lactones has been studied for some years because the resulting polymers have a certain industrial interest in various fields because of their biodegradability and biocompatibility. Thus, copolymers with biodegradable polyesters can be used as a drug encapsulant or as biodegradable implants, particularly in orthopedics, to suppress the interventions that were necessary in the past to remove metal parts such as pins for example. Such polymers can also be used in coating and plastic formulations. The Applicant has therefore been interested in these polymers for incorporating them into block copolymers, because of their biodegradability, so that they can be easily removed after nano-structuring and allow the creation of a residual porous film intended to serve as a mask. of nanolithography, in the context of applications in lithography by DSA (of the Anglo-Saxon acronym "Directed Self Assembly"). Polycaprolactones and polybutyrolactones also have good physico-chemical properties and good thermal stability up to temperatures of at least 200-250 ° C.

Organo-catalysts have been developed to allow the ring opening polymerization of lactones, in particular ε-caprolactone noted "ε-CL" in the following description. Patent Applications WO2008104723 and WO200810472 and the article entitled "organo-catalyzed ROP of ε-caprolactone: methanesulfonic acid competes with trifluoromethanesulfonic acid" macromolecules 2008, Vol. 41, p. 3782-3784, have notably demonstrated the effectiveness of methanesulfonic acid, denoted "AMS", as a catalyst for the polymerization of ε-caprolactone. The documents cited above also describe that in combination with a protic initiator of alcohol type, AMS is capable of promoting the controlled polymerization of the cyclic monomer α -caprolactone. In particular, the protic initiator allows fine control of average molar masses as well as chain ends. Furthermore, it is also known that when the blocks of a block copolymer have glass transition temperatures T _g or T _m melting high, it may be necessary to perform annealing at a high annealing temperature to to promote nanostructuring. If the annealing treatment is to be carried out at a high temperature, typically above 200 ° C, and with slow segregation kinetics, this can lead to copolymer stability problems and higher processing costs.

The Applicant was therefore interested in the behavior of block copolymers comprising a biodegradable block.

[Technical problem] [0018] The object of the invention is therefore to remedy at least one of the disadvantages of the prior art. The invention aims in particular to provide a block copolymer film comprising at least a first biodegradable block, said block copolymer film being capable of nanostructuring in nanodomains with a controlled period of less than 20 nm, after a one-time annealing. moderate temperature, less than 200 ° C and preferably less than 180 ° C and with a kinetics less than 30 minutes, preferably less than 15 minutes. [Brief description of the invention!

Surprisingly, it has been discovered that a nano-structured block copolymer film in nano-domains, said copolymer comprising at least a first biodegradable block and a second block of a different chemical nature of the first block, said copolymer characterized in that the first biodegradable block is amorphous and in that the second block is derived from an oligomer or a polymer carrying a hydroxy function on at least one end and acting as a macro-initiator of the polymerization of the first block,

allows obtaining nano-domains with a period of less than 20 nm after an annealing at a temperature between 130 and 170 ° C for a period of between 5 and 10 minutes.

[0020] According to other optional features of this block copolymer film:

the first amorphous biodegradable block is of polyester type;

the first amorphous polyester-type biodegradable block is chosen from polymers of ε- or δ-lactones substituted or unsubstituted by aryl or alkyl groups;

the first amorphous polyester-type biodegradable block is an amorphous caprolactone (PCL _am ) copolymer formed from ε-caprolactone and at least one other comonomer selected from ε- or δ-lactones substituted with aryl or alkyl groups ;

the block copolymer is a diblock or triblock copolymer;

the comonomers of constitution of the amorphous caprolactone copolymer (PCLam) are ε-caprolactone (ε-CL) and 4-phenyl-caprolactone (4-Phl-CL);

the molar ratio between the ε-CL / 4-Ph ^-CL comonomers is between 6/1 and 3/1, preferably between 6/1 and 4/1;

the number-average molecular mass of each block of amorphous caprolactone copolymer (PCLam) is between 1000 and 30000 g / mol, preferably between 2000 and 15000 g / mol;

the number-average molecular weight of the block copolymer is between 7000 and 33000 g / mol;

the molar ratio of? -caprolactone and 4-Ph? -CL co-monomers on each hydroxyl function of the macro-initiator is between 16/1 and 130/1; the second macro-initiator block is derived from a mono- or polyhydroxylated oligomer or polymer chosen from: (alkoxy) polyalkylene glycols, such as (methoxy) polyethylene glycol (MPEG / PEG), polypropylene glycol (PPG) and polytetramethylene glycol (PTMG); poly (alkyl) alkylene adipate diols such as poly (2-methyl-1,3-propylene adipate) diol (PMPA) and poly (1,4-butylene adipate) diol (PBA); polysiloxanes, such as mono or di-hydroxylated polydimethylsiloxane (PDMS), mono or di-carbinols, or optionally hydrogenated mono- or dihydroxylated polydienes, such as α, γ-dihydroxylated polybutadiene or α, ω-dihydroxylated polyisoprene; preferably hydroxytelechelic polybutadiene hydrogenated or not; or mono- or polyhydroxy polyalkylenes such as mono- or polyhydroxylated polyisobutylene; modified or unmodified polysaccharides such as starch, chitin, chitosan, dextran, and cellulose; or a co-oligomer or a vinyl copolymer of the family of acrylic, methacrylic, styrenic or diene polymers, which results from a copolymerization between acrylic, methacrylic, styrenic or diene monomers and functional monomers having a hydroxyl group, or a copolymer vinylic polymer obtained by radical polymerization, which can be controlled or not, in which the radical initiator and / or the control agent carry at least one hydroxyl or thiol function;

From this block copolymer film, it is possible to produce a nano-lithography mask by removing the first amorphous biodegradable block to form a porous pattern perpendicular to the surface to be etched and having a period U ≤ 20 nm . Other features and advantages of the invention will become apparent on reading the following description, given by way of illustrative and non-limiting example:

[Detailed description of the invention]

The term "monomer" as used refers to a molecule that can undergo polymerization.

The term "polymerization" as used refers to the process of converting a monomer or a mixture of monomers into a polymer. The term "oligomer" as used refers to a small polymer compound, comprising between 2 and 30 monomers, that is to say, whose degree of polymerization is between 2 and 30.

By "copolymer block" or "block" is meant a polymer comprising several monomer units of several types, or of the same type.

The term "block copolymer" means a polymer comprising at least two blocks as defined above, the two blocks being different from one another and having a phase segregation parameter such that they are not miscible and separate into nano-domains at a temperature below the degradation temperature of the block copolymer.

The term "miscibility" used above refers to the ability of two compounds to mix completely to form a homogeneous phase.

The block copolymer according to the invention advantageously comprises a first biodegradable block, capable of being easily removed after nanostructuration of the copolymer, so as to produce a porous film intended to serve as a nanolithography mask. The block copolymer comprises at least one other block, different from the first, and which is incompatible with the first block, that is to say that they can not mix and separate into nano-domains.

[0030] Advantageously, the first biodegradable block has an amorphous structure.

More particularly, the first amorphous biodegradable block is of polyester type. Among the polyesters capable of forming this first amorphous block, for example, amorphous polymers of ε-lactone monosubstituted by linear or branched, optionally substituted aryl or alkyl groups, or amorphous polymers of δ-lactone monosubstituted by groups may be selected. aryl or alkyl, linear or branched, optionally substituted. This may for example be an amorphous polybutyrolactone type polymer (noted PBL _a m), or amorphous polycaroplactone type (noted, for the sake of simplification, PCL _am in the following description).

More preferably, the first amorphous block is an amorphous polycaprolactone (PCL _am ). PCL is a semi-crystalline polymer that has a moderate TM (60 ° C) melting temperature and a low T _g (-60 ° C) glass transition temperature. Due to these moderate to low temperatures, the applicant has speculated that they would promote a phase segregation of the block copolymer at a moderate annealing temperature, preferably below 200 ° C, and with favorable kinetics, preferably less than 30 minutes.

However, the Applicant has found that, surprisingly, the block copolymers comprising a PCL semi-crystalline polycaprolactone block have no nanoscale structuring. Even if these block copolymers nanostructure when they are annealed at a temperature of about 100 ° C for 12 hours, at the time of cooling to room temperature, crystals appear which destroy the nanostructuration of the nanostructures. Block copolymers obtained, so that at room temperature, the block copolymers have no nanostructuration. On the other hand, when the polycaprolactone block is rendered amorphous by random copolymerization of ε'-caprolactone with a co-monomer of a similar nature, a segregation resulting in nanoscale structuring is observed in the solid state and that same at room temperature, after cooling after annealing at a temperature of about 100 ° C for 12h.

The second block, meanwhile, is formed from an oligomer or a polymer whose chemical nature is incompatible with the first block and comprising an alcohol function on at least one end. This second functionalized alcohol polymer serves to serve as a macro-initiator for the polymerization of the first block, in particular polycaprolactone in the presence of methanesulfonic acid (AMS) as catalyst. When it comprises only a hydroxyl function on one end, it makes it possible to produce a diblock copolymer with the PCL. When it comprises a hydroxyl function at both ends, it makes it possible to synthesize a triblock copolymer, with PCL blocks at the ends.

In the case of producing a film based on such a block copolymer, comprising an amorphous PCL block (PCL _am ), an annealing treatment at a temperature of between 130 and 170 ° C. for a period of time. very short, advantageously less than 10 minutes and preferably between 1 and 5 minutes, is sufficient to observe a nanostructuration in the block copolymer film. In this case, the treatment of the film by annealing at a temperature below 180 ° C. makes it possible to improve the mobility of the polymer chains and to accelerate the structuring kinetics of the copolymer.

[0036] Preferably, the amorphous caprolactone copolymer, intended to form the first block copolymer polyester block, is obtained by copolymerization of ε'-caprolactone with a monomer of similar nature. By "nature monomer close to Ι'ε-CL" is meant a monomer of the monosubstituted ε-lactone or monosubstituted δ-lactone type. Advantageously, the amorphous PCL is thus formed from ε-caprolactone and from at least one other comonomer selected from ε- or δ-lactones substituted with aryl or alkyl groups. Among these monomers of a similar nature, it appears that 4-Phenyl-caprolactone, denoted 4-ΡΙπ-ε-ΟΙ in the rest of the description, is the preferred comonomer, since it makes it possible to render the caprolactone copolymer amorphous to a low molar rate, of the order of 15 to 20%. The comonomers of caprolactone and 4-phenyl-caprolactone thus make it possible to form a random copolymer of poly (4-phenyl-caprolactone-ε-caprolactone), hereinafter denoted P (4-Ph---CL-r). - ε-CL).

The fact of replacing a block of PCL of crystalline structure with an amorphous block consisting of a random copolymer of caprolactone has already been described in the literature, but never in order to obtain a nanostructuration of block copolymers intended for serve as nanolithography masks. In addition, in these cases, the proportions of comonomer required to inhibit the crystallinity of PCL are high and between 33 and 50%.

Thus, R. Jerome, RE Prud'home et al., In the article entitled "Synthesis, characterization, and miscibility of caprolactone random copolymers", Macromolecules, 1986, 19, 1828, have shown that the statistical copolymerization of Ε-caprolactone with 6-Me-caprolactone makes it possible to obtain amorphous copolymers for a ratio of monomers of 50/50. These amorphous copolymers have better miscibility with PVC than semicrystalline polycaprolactone, the formation of crystals decreasing this miscibility. These amorphous copolymers are biodegradable and are intended to be used for producing subcutaneous implants for drug delivery.

In the article entitled "Triblock copolymers of ε-caprolactone, L-lactide and trimethylene carbonate: biodegradability and elastomeric behavior", J. Biomedical materials research, part A 201 1, 99A, 38 LK Widjaja et al. also showed the impact of the crystalline / amorphous nature in the case of plastic elastomeric polymers. When triblock copolymers of PLA-b-PCL-b-PLA are prepared, the semi-crystalline nature of the PCL hardens the central block thus decreasing the elastomeric character. Thanks to the random copolymerization of ε-caprolactone with trimethylene carbonate, an amorphous central block is obtained for a 50/50 ratio of the monomers, which significantly increases the elastic properties.

Finally, in the article entitled "Poly (lactide) -block-poly (ε-caprolactone-co-β-decalactone) -block-poly (lactide) copolymer elastomers", Polym. Chem. 2015, 6, 3641, M. Hillmyer et al. have studied triblock copolymers of PLA-b-PCL-b-PLA, whose PCL central block is semi-crystalline and of PLA-6-P (CL-r-DL) -i -PLA whose central block P (CL -r-DL) is amorphous for a CL / DL ratio of 66/33. They showed that, in both cases, there is a micro-phase separation to lead to lamellar or cylindrical morphologies, depending on the composition. The structure obtained is micrometric and non-nanometric. This article therefore does not show an impact of the semi-crystalline or amorphous character on the segregation properties of the copolymer obtained. In addition, the additional experimental material published in the appendix to this article explains that the SAXS analyzes carried out to demonstrate the microseparation of the phases are carried out after annealing at 120 ° C. for 12 hours and then at 60 ° C. for 8 hours. The kinetics of structuring of these copolymers is therefore very slow.

The second polymer forming the second block of the block copolymer according to the invention and acting as macro-initiator of the polymerization of the first block, and more particularly of the random copolymer of caprolactone, can advantageously be chosen from an oligomer or a polymer mono- or polyhydroxy, especially chosen from: (alkoxy) polyalkylene glycols, such as (methoxy) polyethylene glycol (MPEG / PEG), polypropylene glycol (PPG) and polytetramethylene glycol (PTMG); poly (alkyl) alkylene adipate diols such as poly (2-methyl-1,3-propylene adipate) diol (PMPA) and poly (1,4-butylene adipate) diol (PBA); polysiloxanes, such as mono or dihydroxylated polydimethyl siloxane (PDMS); mono or di-carbinol, optionally hydrogenated, α-hydroxylated or α, ω-dihydroxylated polydienes such as α, γ-dihydroxylated polybutadiene or α, ω-dihydroxylated polyisoprene; mono- or polyhydroxylated polyalkylenes such as mono- or polyhydroxylated polyisobutylene; modified or unmodified polysaccharides such as starch, chitin, chitosan, dextran, and cellulose; and their mixtures.

According to another possibility, the macro-initiator may be a co-oligomer or a vinyl copolymer of the family of acrylic, methacrylic, styrenic or diene polymers, which results from a copolymerization between acrylic monomers, methacrylic, styrenic or dienes and functional monomers having a hydroxyl group, such as hydroxylated acrylic or methacrylic monomers, such as, for example, 4-hydroxybutyl acrylate, hydroxyethyl acrylate and hydroxyethyl methacrylate. This polymerization can be carried out according to a conventional free radical process, a controlled radical process or an anionic process.

According to another possibility, the macro-initiator may be a vinyl copolymer obtained by controlled radical polymerization, or not, in which the radical initiator and / or the control agent carry at least one hydroxyl or thiol function.

Preferably, the macro-initiator is advantageously chosen from hydroxylated polyolefins, that is to say any polymer derived from olefins bearing at least one hydroxyl function or telechelic hydroxy. In particular, the polydienes are referred to and among these, polybutadienes are preferred, and especially telechelic hydroxy polybutadiene.

More preferably, the telechelic hydroxy polybutadiene is a polymer marketed by Cray Valley under the commercial reference Kraso ® and more particularly Krasol LBH-P3000 ^® and Krasol HLBH-P3000 ^® . The Krasol LBH-P3000 ^® is a polybutadiene prepared by anionic polymerization, having an average molecular weight M _n is in the range of 3500 g / mol. The Krasol HLBH-P3000 ^® is a hydrogenated polybutadiene having an average molecular weight M _n is in the range of 3100 g / mol. Such telechelic hydroxy polybutadienes then act as macro-initiators of the polymerization of the first amorphous block, and more particularly of the constituent comonomers of the amorphous caprolactone copolymer (PCL _am ). These macro-initiators, dihydroxylated, make it possible to synthesize triblock copolymers of PCL-Krasol®-PCL with a central block of polybutadiene type (PBT) hydrogenated or not. The formulas Krasol LBH-P3000 ^® and Krasol HLBH-P3000 ^® used are as follows:

Krasol LBH-P3000 Krasol HLBH-P3000

The number-average molecular mass of each PCLam amorphous PCL block is advantageously between 1000 and 30000 g / mol and preferably between 2000 and 15000 g / mol.

The number-average molecular weight of the block copolymer obtained is between 7000 and 33000g / mol.

For obtaining an amorphous copolymer of Poly (s-CL-r-4-Ph-s-CL), the molar ratio in s-CL / 4-Ph-s-CL is between 6 / 1 and 3/1, and preferably between 6/1 and 4/1, which corresponds to a molar percentage of 4-Ph-s-CL preferably between 15 and 20%.

The block copolymer thus produced is then deposited as a film on a substrate. The process for producing such a block copolymer film comprises the steps of synthesizing the block copolymer by mixing the macro-initiator, for example a hydroxylated polyolefin macro-initiator, and more particularly a hydroxylated or di-substituted polybutadiene. hydroxylated, with the comonomers of ε-CL and 4-Ph---CL, in a solvent, in the presence of methanesulfonic acid as a catalyst for the polymerization reaction of the aforementioned comonomers, for the selective production, in a step, a PCL block copolymer _has _m-PBT-PCL m. The solvent is advantageously chosen from toluene, ethylbenzene or xylene. Toluene is however preferred to the other two solvents. The catalyst is then removed and the solution of the block copolymer obtained is applied in the form of a film on a surface to be etched, the surface energy of which has been neutralized beforehand. The solvent of the solution is evaporated and the film is annealed at a specified temperature of between 130 and 170 ° C, for a period of less than 30 minutes, and preferably less than 15 minutes, to ensure the nano-structuring of the copolymer in nano-domains perpendicular to the surface to be etched. An annealing temperature of between 130 and 170 ° C. is sufficient to obtain nanostructuring in a short period of time of the order of a few minutes, preferably less than 15 minutes, and more preferably less than 5 minutes and ideally 1 to 2 minutes.

In general, in the case of lithography, the desired structure, for example the generation of nano-domains perpendicular to the surface, however, requires the preparation of the surface on which the copolymer solution is deposited in order to control surface energy. Among the known possibilities, there is deposited on the surface a random copolymer whose monomers may be identical in whole or in part to those used in the block copolymer that is to be deposited. In a pioneering article Mansky et al. (Science, vol 275 pages 1458-1460, 1997) describes this technology well, now well known to those skilled in the art.

Among the preferred surfaces include surfaces made of silicon, silicon having a native or thermal oxide layer, germanium, platinum, tungsten, gold, titanium nitrides, graphenes, BARC (bottom anti-reflective coating) or any other anti-reflective layer used in lithography.

Once the surface prepared, a solution of the block copolymer according to the invention is deposited and the solvent is evaporated according to techniques known to those skilled in the art such as the so-called "spin coating" technique, "Doctor Blade "," Knife system "," slot die System "but any other technique can be used such as a dry deposit, that is to say without going through a prior dissolution.

Subsequently, a heat treatment is carried out which allows the block copolymer to organize properly, that is to say to obtain in particular a phase separation between the nano-domains whose size is less than 10. nm, with a controlled morphology of the nano-domains and with a period less than 20 nm, a preferential orientation of the domains, perpendicular to the surface to be etched, and a reduction in the number of defects. Preferably, the temperature T of this heat treatment is such that it is less than 180 ° C and higher than the highest glass transition temperature of the blocks constituting the copolymer. It is carried out under a solvent or a thermal atmosphere or by a combination of these two methods.

[0055] Depending on whether the macro-initiator is mono or dihydroxy the obtained copolymer is a diblock copolymer type _am -PBT PCL or PCL triblock _a _m-PBT-PCL m.

The synthesis of the block copolymer according to the invention is preferably carried out at a temperature ranging from 20 to 120.degree. C. and more preferably between 30 and 60.degree. especially when the solvent is toluene. When the macro-initiator is a hydroxytelechelic polybutadiene, hydrogenated or not, it is indeed possible to obtain, at a temperature of the order of 30 ° C., block copolymers of PCLam-b-Krasol®-b-PCLam. or PCLam-b-Krasol® Η-β-PCL _am having an average molecular weight in number M _{n of} up to 33000 g / mol in a few hours and with a yield greater than or equal to 85% after purification.

The molar ratio initiator / catalyst (AMS) is preferably between 1/1 and 1/2.

Finally, the reagents used in this process are preferably dried before being used, in particular by vacuum treatment, distillation or drying with an inert desiccant.

The cylindrical or lamellar morphology of the nano-domains thus formed depends on the molar ratio of ε-CL and 4-Ph---CL co-monomers on the macro-initiator in the initial mixture, but also on the nature of the macro-initiator. initiator forming the second block of the block copolymer and its degree of polymerization.

The molar ratio of ε-CL and 4-Ph---CL co-monomers with respect to each functional end of the macro-initiator is preferably between 16/1 and 130/1.

After having synthesized the block copolymer, having deposited it in the form of a film on a surface to be etched and subjected to annealing according to the process just described, the first block of PCL _am , biodegradable , is advantageously removed to form a nanolithography mask comprising a porous pattern perpendicular to the surface to be etched and having a Lo≤ 20 nm period.

A block copolymer according to the invention therefore makes it possible to obtain an assembly of the blocks perpendicular to the surface on which it is deposited, with a significant phase segregation, making it possible to obtain nano-domains of small sizes, of the order of a nanometer to a few nanometers and controlled morphology, and a period less than or equal to 20nm. Such a block copolymer therefore allows better control of the lithography process whose resolution is high and compatible with the current requirements in terms of component dimensions.

The inhibition of crystallinity in block copolymers comprising a block of PCL obtained by random copolymerization of ε-CL with 4-Ph-s-CL, with only 15% to 20 mol% of the co-monomer of 4-Ph-s-CL, allows to obtain block copolymers capable of segregating, giving rise to structuring at the nanoscale, while no nano-structuring is observed for the copolymers comprising a semicrystalline block of PCL.

In addition, the copolymers obtained based on amorphous polyester, and more particularly amorphous PCL, are capable of segregating at low molar masses, typically between 4000 and 30000 g / mol, by treatment at low annealing temperatures. high (<180 ° C) and in a very short time (<10 min). Well-defined domain morphologies are then obtained with low U periods (<20 nm).

This behavior is particularly interesting in the context of applications in lithography by DSA (Directed Self Assembly) where one seeks to obtain nanostructuring in periodic structures with very low copolymer periods, if possible at low temperature and in short times, in order to obtain lithography masks with very high resolutions.

The following examples illustrate in a non-limiting way the scope of the invention:

For the preparation of block copolymers by ring-opening polymerization of lactones and cyclic carbonates with sulphonic acids as catalysts, triblock copolymers based on semi-crystalline polycaprolactone (PCL) and poly (4-phenyl-caprolactone) amorphous -r-caprolactone) were prepared for comparison. Krasol LBH-P3000® and Krasol HLBH-P3000® dihydroxylated telechelic polymers were used as macro-initiators, in order to have a hydrogenated or unsubstituted polybutadiene-type central block.

The sulphonic acid used as catalyst in the copolymerization reaction is methanesulfonic acid (AMS).

The copolymerization reactions of the monomer of ε-CL and of the poly (4-Ph---CL-r---CL) copolymer with the macro-primers of KrasoILBH and of AMS as a catalyst, are as follows

-6-Krasol-6-PCL

R = H (s-CL), Ph (4-Ph-s-CL)

The following general procedure was used to implement the methods described below.

The toluene is dried using a MBraun SPS-800 solvent purifier. Methanesulfonic acid (AMS) was used without further purification. Diisopropyl ethylamine (DIEA) was dried and distilled on Cah and stored on potassium hydroxide (KOH). The ε-caprolactone dried on Cah then distilled is stored under an inert atmosphere. 4-Ph-? -CL was recrystallized with toluene then dried over P2O5 and stored under an inert atmosphere.

The Schlenk tubes were dried with a vacuum heat gun to remove any trace of moisture.

The reaction was monitored by ¹ H NMR (proton nuclear magnetic resonance) on Brucker AVANCE devices 300 and 500 and steric exclusion chromatography (SEC) in THF. To do this, samples were taken, neutralized with DIEA (Diisopropylethyl-amine), evaporated and taken up in a suitable solvent for their characterization. The ¹ H NMR makes it possible to quantify the degrees of polymerization (DP) of the ε-CLet comonomers of 4-Ph---CL by making the integration ratio of half of the signals of the -CH 2 - carrying the OC function. (= O) and the C = O function respectively, to the CH2 proton signals carrying the -OH function initially on the initiator. The spectra are recorded in deuterated chloroform, spectrometer at 300 MHz. The number-average molecular weight Mn and the degree of polydispersity (D) of the samples of copolymers taken are measured by steric exclusion chromatography SEC in THF with polystyrene calibration. The differential scanning calorimetry measurement, denoted DSC, makes it possible to study glass transitions and crystallization. DSC, the English acronym "Differential Scanning Calorimetry" is a thermal analysis technique to measure the differences in heat exchange between a sample to be analyzed and a reference during phase transitions. To carry out this study, a NETZCH DSC204 differential scanning calorimeter was used.

The calorimetry analyzes were carried out between -80 and 130 ° C. and the temperature values were recorded during the second temperature rise (at a rate of 10 ° C./min).

Small angle X-ray scattering analysis, denoted SAXS (the Anglo-Saxon acronym "Small Angle X-rays Scattering") makes it possible to study the structural properties of synthesized block copolymers at a lower scale. at 100nm. This analysis technique consists of diffusing a monochromatic radiation through the sample to be analyzed. The scattered intensity is collected as a function of the scattering angle passing through the sample, the scattering angle being very close to the direct beam. The scattered photons provide information on the fluctuation of electron densities in the heterogeneous material. For SAXS analysis, a Nanostar SAXS (Bruker) or BM-26B DUBBLE station at the European Synchrotron Radiation Facility (ESFR) was used.

In the examples which follow, triblock copolymers based on semi-crystalline polycaprolactone (PCL) on the one hand and based on amorphous poly (£ -CL-co-4-Ph---CL) on the other hand. have been prepared and compared.

In all cases the polymerization of PCL or P (CL-co-4-Ph-CL) is complete and it takes place with very good control, that is to say with effective incorporation of the block. polyester on the hydroxylated ends of polybutadienes (krasol) and with a very low impact of transfer reactions. The block structure of the copolymers is confirmed by NMR and CES analyzes of the polymers.

The ability of these copolymers to segregate and nanostructure was first studied by DSC and then SAXS and / or microscopy analysis was also performed. The results of the analyzes are collated in Table I below. Example 1 (Comparative) Preparation of a triblock copolymer poly (g-caprolactone) _{April 3-fe} / oc-Krasol LBH-P3000-6 / oc-poly ^(g -caprolactonek3

The macroinitiator (Krasol LBH-P3000, 1 eq., 1 .5 g) and I 'ε-CL (90 eq., 4.1 1 g) is weighed in a glove box and introduced into a dry schlenk. The schlenk is placed under a controlled atmosphere of argon, and then the solvent (9 mL of toluene, [s-CL] o = 4 mol / L) and methane sulphonic acid (1 eq., 78 μί) are successively added. The reaction medium is stirred under argon at 30 ° C. for 2 h 30 min. Once the monomer has been fully consumed, established from ¹ H NMR monitoring, an excess of diisopropylethylamine (DIEA), or Amberlyst 21, is added to neutralize the acid catalyst. The solvent is then evaporated under vacuum. The polymer obtained is then dissolved in the minimum of dichloromethane, then precipitated by addition in cold methanol, filtered and dried under vacuum.

The polymerization reaction of the ε-CL monomer with the macro-initiator is as follows:

PCL-b-b-PCL-Krasol

The results obtained are as follows:

[0081] This gives a triblock copolymer PCL ₄ 3- £> -Krasol® - £> -PCL ₄ 3 with a 99% conversion and a yield higher than 90%

CES: M _n = 18,000g / mol; D = 1 .18

[00831 DSC: T _g : -55.4 ° C; T _f : 52.7 ° C; hstaiiinité overall rate _C = 45%

[00841 ¹ H NMR (CDCl₃ 300MHz.): 5.70-5.20 (m, 40x1 H, = CH ₂ + CHÇ_H 2x2x10H, -CH = C_h C_h-CH-), 5.00-4.80 (m, 1 x4Qx2H, CH-CH = CH ₂ ), 4.10-4.00 (m, 86x2H, OCH ₂ CH ₂ ), 3.70-3.60 (m, 2 × 2H, CH ₂ OH terminals), 2.40-2.20 (m, 86 × ₂ H, COCH ₂ ), 2.20-1.75 (m, 40x1H, CH ₂ = CH ₂ + 2x2x 10x2H, -CH ₂ -CH = CH-CH ₂ -), 1.70-1.50 (m, 2 ^χ 86 ^χ 2Η, COCH ₂ CH ₂ CH ₂ CH ₂ CH ₂ O), 1.45-1.10 (m, 86x2H, COCH ₂ CH ₂ CH ₂ CH ₂ CH ₂ O, 40x2H, CH ₂ -CH ₂ -CH). Example 2 (Invention): Preparation of a triblock copolymer "PCL _am " ₄₂ -fo- Krasol LBH-P3000-6- "PC _m '\?

The macroinitiator (Krasol LBH-P3000, 1 eq., 0.53 g) as well as Ι'ε-CL (72 eq., 1 .16 g) and the 4-Ph-s-CL (18 eq., 0.48 g). (g) are weighed in a glove box and placed in a dry pan. The schlenk is placed under a controlled atmosphere of argon, and then the solvent (12.6 ml of toluene, [M] o = 1 mol / L) and the methanesulfonic acid (2 eq., 19 μί) are successively added. The reaction medium is stirred under argon at 30 ° C. for 1 h 10. Once the monomer has been fully consumed, established from ¹ H NMR monitoring, an excess of diisopropylethylamine (DIEA), or Amberlyst 21, is added to neutralize the acid catalyst. The solvent is then evaporated under vacuum. The polymer obtained is then dissolved in the minimum of dichloromethane, then precipitated by addition in cold methanol, filtered and dried under vacuum.

The results obtained are as follows:

A triblock copolymer of "PCL _am ." 42-6-Krasol LBH-P3000- "-" PCLam. "42 was obtained with a conversion of 88% and a yield greater than 83%.

CES: M _n = 13000 g / mol; D = 1.23

[00881 DSC: T _g : -53.8 ° C; T _f : - amorphous

¹ H NMR (CDCl ₃ 300MHz): 7.40-7.10 (m, 12 × 5H, Ph, CH ₃ ), 5.70-5.20 (m, 40 × 1 H, CH ₂ -CH = CH ₂ + ₂ × ₂ × 10H, -CH-C-H = CH-CH- ), 5.00-4.80 (m, 1 x 40x2H, CH-CH = CH ₂ ), 4.05-3.75 (m, 70x2H, CH ₂ O (C = O) C + 12x2H, CH ₂ O (C = O) C), 3.70-3.45 (m, 2 ^χ 2Η, _H ₂ OH terminals), 2.70-2.50 (m, 12x1H, _H (C ₆ H ₅ )), 2.40-2.20 (m, 70x2H, COCH ₂ ), 1.75- 2.20 (m, 12x2H, O (C = O) CH ₂ , 12x2x2H, O (C = O) CH ₂ CH ₂ CHCH ₂ , 40x1H, CH ₂ = CH ₂ + 2x2x1 Qx2H, -CH ₂ -CH = CH-CH ₂ -), 1 .70-1 .50 (m, 2x70x2H, COCH ₂ CH ₂ CH ₂ CH ₂ CH ₂ O), 1 .45-1 .10 (m, 2 ^χ ^{χ 2Η} 40, COCH ₂ CH ₂ CH ₂ CH ₂ CH ₂ O, 40x2H, CH ₂ -CH ₂ -CH).

Example 3 (Comparative): Preparation of trifunctional polyfunctional caprolactone copolymer / oc-Krasol HLBH-P3000-6 / oc-poly (g-caprolactone)

The macroinitiator (Krasol HLBH-P3000, 1 eq., 0.33 g) and I 'ε-CL (70 eq., 0.75 g) are weighed in a glove box and introduced into a dry schlenk. The schlenk is placed under a controlled atmosphere of argon, and then the solvent is added successively (6.6 ml of toluene, [s-CL] o = 1 mol / l) and methanesulfonic acid (2 eq., 7.3 μΙ_). The reaction medium is stirred under argon at 30 ° C. for 1 h 30 min. Once the monomer has been fully consumed, established from ¹ H NMR monitoring, an excess of diisopropylethylamine (DIEA), or Amberlyst 21, is added to neutralize the acid catalyst. The solvent is then evaporated under vacuum. The polymer obtained is then dissolved in the minimum of dichloromethane, then precipitated by addition in cold methanol, filtered and dried under vacuum.

The results obtained are as follows:

A triblock copolymer of poly (ε-caprolactone) 36-ib / α-Krasol HLBH-P3000-β-poly (ε-caprolactone) 36 with a conversion level of greater than 99% and a higher yield is obtained. at 90%.

[00921 CES: M _n = 20,000g / mol; D = 1 .04

[00931 DSC: T _g : -55 ° C; T _f : 53.4 ° C; globalcreatal rate = 42%

[00941 ¹ H NMR (CDCl3, 300MHz)?: 4.10-4.00 (m, 72x2H, CH ₂ O (C = O) C), 3.70-3.60 (m, 2 ^{χ 2Η,} CH2OH terminals), 2.40-2.20 (m, 72x2H, COCH _2), 1 .70-1 .50 (m, 2 ^χ 72 ^{χ 2Η,} COCH2CH2CH2CH2CH2O), 1 .45-0.95 (m, 72x2H, COCH2CH2CH2CH2CH2O, 36x1 H, CH ₂ CH ₂ -Ç_H-2 + ^χ 36 ^χ 2Η, CH 2 CH 2 -CH 3 + 2x4x 10x 2 H, -CH 2 -CH 2 -CH 2 -). 0.95- 0.75 (m, 36x3H, CH2-CH3) Example 4 (Invention): Preparation of a triblock copolymer "PCL _am " ₃ e-fe-Krasol HLBH-P3000-6- "PC _m

The macroinitiator (Krasol HLBH-P3000, 1 eq., 0.55 g) as well as Ι'ε-CL (56 eq., 1 .16 g) and 4-Ph-s-CL (14 eq., 0.48 g). (g) are weighed in a glove box and placed in a dry pan. The schlenk is placed under a controlled atmosphere of argon, and then the solvent (3.7 mL of toluene, [β-BLJo = 4 mol / L) and trifluoromethanesulphonic acid (2 eq., 45 μί) are successively added. The reaction medium is stirred under argon at 30 ° C. for 1 h 15 min. Once the monomer has been fully consumed, established from ¹ H NMR monitoring, an excess of diisopropylethylamine (DIEA), or Amberlyst 21, is added to neutralize the acid catalyst. The solvent is then evaporated under vacuum. The polymer obtained is then dissolved in the minimum of dichloromethane, then precipitated by addition in cold methanol, filtered and dried under vacuum. The results obtained are as follows:

There is obtained a triblock copolymer of "PCL _AM ." 36-ib-Krasol ΗΙ_ΒΗ-Ρ3000-> - "PCI_am." 36 with a degree of conversion greater than 99% and a yield greater than 90%.

CES: M _n = 14,500 g / mol; D = 1.23

DSC: T _g : -54.2 ° C; T _f : -amorphous

[00991 ¹ H NMR (CDCl ₃ 300MHz.): 7.35-7.00 (m, 11x5H, Ph, Ç_HCI _3), 4.10-3.75 (m, 56x2H, CH ₂ O (C = O) C + 11x2H, CH ₂ O ( C = O) C), 3.70-3.45 (m, 2x2H, CH ₂ OH terminals), 2.70-2.50 (m, 11 x 1 H, CH (C ₆ H ₅ )), 2.40-2.20 (m, 56x2H, COCH _2). ), 2.15-1.75 (m, 11x2H, O (C = O) CH ₂ , 11X2X2Η, O (C = O) CH ₂ CH ₂ CHCH ₂ ), 1.70-1.50 (m, 2 ^χ 56 ^χ 2Η, COCH ₂ CH) ₂ CH ₂ CH ₂ CH ₂ O), 1.45-0.95 (m, 56x2H, COCH ₂ CH ₂ CH ₂ CH ₂ CH ₂ O, 36x1H, CH ₂ -CH-CH ₂ + 2 ^χ 36 ^χ 2Η, CH-CH 2 -CH3 + 2x4x10x2H, -CH2-CH2-CH2-). 0.95-0.75 (m, 36x3H, CH ₂ -CH ₃ ).

The thermal analyzes (DSC) of the copolymers studied show a single glass transition because of the values very close to the T _g of the two blocks (PCL, -60 ° C. and Krasol -55 ° C.). Given the proximity of the T _g values of the corresponding homopolymers (PCL, -60 ° C and Krasol -55 ° C) it is difficult to conclude as to the ability of these blocks to segregate only with DSC analysis. It should also be noted that the block copolymers comprising the PCL block are semi-crystalline in nature, while those with the PCL _am block are amorphous in nature.

The SAXS analyzes provide more light on the different behavior of the block copolymers according to whether they incorporate end blocks PCL or PCL _am . For copolymers based on PCL (semi-crystalline), there is no nano-structuring of well-defined morphology, but simply a phase separation due to the crystallinity of PCL, amorphous PCL / Krasol phases seem miscible. On the other hand, in the case of the PCLam block, nano-structuring with a well-defined morphology is observed, in particular with hydrogenated Krasol. The nanostructuring morphology is cylindrical for the cases observed and summarized in Table I below. FIG. 1 illustrates the curve obtained by SAXS analysis of a PCL _AM 65-ib-Krasol film PCL _AM 65 with q corresponding to the scattering angle over the wavelength used, * corresponding more particularly to the most intense diffusion. The values of q / q ^* obtained for the different peaks (1, Λ / 4, Λ / 7, V9) are characteristics of a hexagonal cylindrical arrangement with an average U period of 17.3nm. The SAXS analyzes of the block copolymers were carried out on the polymers as obtained during the synthesis-purification, after annealing at 100 ° C. for 12 hours.

The triblock copolymers of Examples 5 to 9 of Table I below were synthesized according to the same protocol as that described in Examples 1 to 4.

The PCLam-6-Krasol-i-PCLam triblock copolymers, or PCLam-6-Krasol Hb-PCLam giving rise to nano-structuring, were then selected for analysis by microscopy, more particularly PCLam-b-Krasol Hb. -PCLam. For this, a copolymer solution is deposited in the form of a thin film with a thickness of 140 nm on a surface, then the solvent is evaporated and the film is annealed at a temperature between 130 and 170 ° C for a time between 5 and 10 minutes. In the examples of Table I above, the PCL _am. 65 "-ib-Krasol Hi -" PCLam.65 film was annealed at a temperature of 150 ° C for 5 minutes. A cylindrical nanostructuring is then observed whose period Lo is equal to 17 nm. The same PCL _am .65 "-ib-Krasol Hi -" PCLam.65 film was also annealed at 170 ° C for 10 minutes. We then observe a cylindrical nano-structuring whose period Lo is equal to 19 nm. The results of analysis by microscopy confirm the nano-structuring, with nano-domains perpendicular to the surface and having an average Lo period of less than 20 nm. The film after 5 minutes annealing at 150 ° C. in FIG. 2 can be viewed by atomic force microscopy (AFM) and the same film after annealing for 10 minutes at 170 ° C. in FIG.

The block copolymers incorporating an amorphous caprolactone copolymer polyester block are therefore capable of segregating, giving rise to structuring at the nanometric scale, whereas no nano-structuring is observed for the equivalent triblock copolymers in size, based on semi-crystalline polycaprolactone.

In addition, the copolymers obtained based on PCL _am are capable of segregating for low molecular weights, typically less than 33000 g / mol, allowing access to various morphologies according to their composition with periods of structuring. very low value, less than 20 nm.

This behavior is particularly interesting in the context of applications in nano-lithography by DSA (Directed Self Assembly) where one seeks to obtain nanostructuring in periodic structures with very low copolymer periods in order to obtain nano-lithography masks with very high resolutions.

The copolymer according to the invention thus differs strongly from conventional PS-b-PMMA block copolymers which do not make it possible to obtain periods lower than 20 nm.

Mn ^* Fraction Fraction Mn ^# D ^# Tg ° Crystallinity

Example Composition ^*

(g / mol) molar molar (g / mol) (° C) overall / relative

Krasol polyester with polyester block ⁰ (%)

1 PCL.43- 13,300 0.26 0.74 18,000 1.18 -55.4 45/61

Krasol-

2 "PCLam.42" - 14,500 0.24 0.76 13,000 1.23 -53.8 0

Krasol- "PCLam.42"

3 PCL36- 1 1,300 0.27 0.73 20,000 1.04 -55 42/58

Krasol H-

4 "PCLam.36" - 12 200 0.24 0.76 14 500 1.23 -54.2 0

Krasol H-

"PCLam.36"

5 PCL21- 8,300 0.42 0.58 14,000 1.12 -45.8 40/69

Krasol-

6 PCLso- 21,800 0.16 0.84 33,000 1.13 -55.6 42/50

Krasol-

PCLso

7 "PCLam.89" - 26 500 0.13 0.87 25 500 1.19 -51.6 0

Krasol- "PCLam.89"

8 PCL70- 19 100 0.16 0.84 27 500 1.10 -53.9 41/49 Krasol H-

9 "PCLam.65" - 19 900 0.16 0.84 21 100 1.21 -53.3 0

Krasol H- "PCLam.65"

'determined by ¹ H NMR (300MHz) with Mn Krasoi- 3 500g / mol and MnKrasoi H- 3 100 g / mol determined by S EC ^#, PS standards;

° determined by DSC T _g Krasoi = -55.4 ° C and TgKrasoi H = -63.8 ° C;

"PCLam." with e-CL / 4-Ph-e-CL = 4/1

Table I

Claims

1. Nano-structured nano-structured block copolymer film, said copolymer comprising at least a first polyester-type biodegradable block and a second block of a different chemical nature from the first block, said block copolymer being characterized in that the first polyester type biodegradable block is amorphous and selected from polymers of ε- or δ-lactones and in that the second block is derived from an oligomer or a polymer carrying a hydroxy function on at least one end and acting as macro-initiator of the polymerization of the first block.

2. Block copolymer film according to claim 1, characterized in that the first amorphous polyester-type biodegradable block is selected from polymers of ε- or δ-lactones substituted or not by aryl or alkyl groups.

3. Block copolymer film according to one of claims 1 to 2, characterized in that the first amorphous polyester-type biodegradable block is an amorphous caprolactone copolymer (PCL _am ) formed from ε-caprolactone and at least one another comonomer selected from ε- or δ-lactones substituted with aryl or alkyl groups.

4. Block copolymer film according to one of claims 1 to 3, characterized in that the block copolymer is a diblock or triblock copolymer.

5. Block copolymer film according to one of claims 3 to 4, characterized in that the co-monomers of constitution of amorphous caprolactone copolymer

(PCLam) are ε-caprolactone (ε-CL) and 4-phenyl-caprolactone (4-Ph ^-CL).

6. Block copolymer film according to claim 5, characterized in that the molar ratio between the comonomers ε-CL / 4-Ph ^ -CL is between 6/1 and 3/1, preferably between 6 / 1 and 4/1.

7. Block copolymer film according to one of claims 3 to 6, characterized in that the number-average molecular weight of each block of amorphous caprolactone copolymer (PCLam) is between 1000 and 30000g / mol, preferably between 2000 and 15000 g / mol.

8. Block copolymer film according to one of claims 1 to 7, characterized in that the number-average molecular weight of the block copolymer is between 7000 and 33000 g / mol.

9. Block copolymer film according to one of claims 3 to 8, characterized in that the molar ratio of ε-caprolactone and 4-Ph---CL co-monomers on each hydroxyl function of the macro-initiator is between 16/1 and 130/1.

10. Block copolymer film according to one of claims 1 to 9, characterized in that the second macro-initiator block is derived from a mono- or polyhydroxylated oligomer or polymer chosen from:

(alkoxy) polyalkylene glycols, such as (methoxy) polyethylene glycol (MPEG / PEG), polypropylene glycol (PPG) and polytetramethylene glycol (PTMG); poly (alkyl) alkylene adipate diols such as poly (2-methyl-1,3-propylene adipate) diol (PMPA) and poly (1,4-butylene adipate) diol (PBA); or

polysiloxanes, such as mono or dihydroxylated polydimethyl siloxane (PDMS), mono or di-carbinol or

- Mono- or dihydroxy polydienes, optionally hydrogenated, such as α, γ-dihydroxylated polybutadiene or α, ω-dihydroxy polyisoprene, preferably hydroxytelechelic polybutadiene hydrogenated or not; or

mono- or polyhydroxylated polyalkylenes such as polyisobutylene mono- or polyhydroxylated; modified or unmodified polysaccharides such as starch, chitin, chitosan, dextran, and cellulose; or

a co-oligomer or a vinylic copolymer of the family of acrylic, methacrylic, styrenic or diene polymers, which results from a copolymerization between acrylic, methacrylic, styrenic or diene monomers and functional monomers having a hydroxyl group, or

a vinyl copolymer obtained by controlled radical polymerization, or not, in which the radical initiator and / or the control agent carry at least one hydroxyl or thiol function.