WO2005068419A1 - Multifunctional and bifunctional dithiocarboxylate compounds, monofunctional alkoxycarbonyl dithiocarbamate compound, a method for the preparation of alkoxycarbonyl dithiocarbamate compounds as well as a method for the preparation of multiblock copolymers by means of radical polymerisation - Google Patents

Abstract

The present invention relates to a multifunctional dithiocarboxylate compound. The present invention furthermore relates to a bifunctional dithiocarboxylate compound. The present invention also relates to a monofunctional alkoxycarbonyl dithiocarbamate compound. The present invention further relates to a method for the synthesis of alkoxycarbonyl dithiocarbamate compounds. In addition, the present invention relates to a method for the preparation of one or more polymers by means of a radical polymerisation process, using a monofunctional, a bifunctional or a multifunctional dithiocarboxylate compound.

Description

Mult functional and bifunctional dithiocarboxylate compounds, monofunctional al oxycarbonyl di hiocarbamate compound, a method for the preparation of alkoxycarbonyl dithiocarbamate compounds as well as a method for the preparation of multiblock copol nnarns βy røearjs of radical polymerisation.

DESCRIPTION The present invention relates to a multifunctional dithiocarboxylate compound. The present invention furthermore relates to a bifunctional dithiocarboxylate compound. The present invention also relates to a monofunctional alkoxycarbonyl dithiocarbamate compound. In addition, the present invention relates to a method for synthesizing an alkoxycarbonyl dithiocarbamate compound. In addition to that, the present invention relates to a method for the preparation of one or more polymers by means of a radical polymerisation process. A method for the preparation of polymers by means of a radical polymerisation process is already known from European patent EP 0 910 587, which relates to a living polymerisation-type radical polymerisation method. According to said method, polymers having a predetermined molecular weight and a narrow molecular weight distribution (low polydispersity of the molecular weight) can be prepared. The method can be used for preparing block copolymers by adding various monomers in successive steps, wherein the polymerisation process is carried out using monofunctional, bifunctional or star-shaped multifunctional chain transfer agents. No mention is made of the use of linear multifunctional chain transfer agents, however. A drawback of said method is the fact that, in order to obtain a linear ultiblock copolymer comprising a desired number of blocks, a large number of polymerisation steps need to be carried out, using a bifunctional chain transfer agent, viz. (n+l)/2 steps for a block copolymer with n blocks, wherein n is an uneven number. Several applications of such linear ultiblock copolymers are known, such as pressure-sensitive adhesives (PSA's), hot melts, compatibi Users for polymer mixtures and composites, impact-modifying agents for thermoplastic elastomers and for imaging applications. The architecture and sequence distribution of the above copolymers are important parameters that determine the solubility of the copolymer and thus the ability of the copolymer to compatibi lise a polymer mixture or function as an adhesive. The sequence distribution of a linear copolymer may vary from alternating to random or block-shaped and plays an essential part in the ability of the copolymer to modify an interface between two phases. To achieve optimum properties, the number of blocks as well as the critical block length are of importance. A polymerisation method that is suitable for synthesis of such multiblock copolymers, while controlling the number of blocks and the block length, is the so-called RAFT polymerisation, or Reversible Addition Fragmentation chain Transfer polymerisation. RAFT polymerisation is a reversible transfer polymerisation process, which belongs to the class of controlled or living radical polymerisation. In the reversible transfer polymerisation method a rapid exchange of growing radicals takes place via a transfer agent. The RAFT polymerisation method is a robust method on account of the tolerance thereof to impurities in the reaction mixture, and in addition it is compatible with a very wide range of different monomers and reaction conditions that can be used. In addition to that, RAFT polymerisation, in addition to being suitable for use in solution, is also suitable for use in heterogeneous systems, such as in aqueous emulsions. A RAFT chain transfer agent, e.g. of the dithiocarboxylate type, is represented by the general formula: Z-C(=S)-S-A. Four types of chain transfer agents of the dithiocarboxylate type can be mentioned, the classification being determined by the structure of the Z-group. The first type is a dithio ester, wherein Z is an al yl or aryl group. Examples thereof are disclosed in European patent No. 0 910 587, French patent application No. 97-16779 and International application WO 98/01478. A drawback of this type of compounds is the fact that they have a deep pink colour as well as a rather pungent odour, which slightly limits the use of the copolymers obtained therewith. A second type is a xanthate compound, wherein Z is an 0-alkyl or 0-aryl group. Examples thereof are disclosed in International applications WO 99/35177 and WO 02/22688. An advantage of these compounds is that they are colourless and have a much less pungent odour. A drawback, however, is the low transfer constant of xanthates, as a result of which a higher polydispersity (~2) will be obtained. A third type is a trithiocarbonate compound, wherein Z is an S-alkyl. Such compounds are disclosed in a publication by Mayadunne (R.T.A. Mayadunne, E. Rizzardo, J. Chiefari, J. Krstina, G. Moad, A. Postma, S.H. Thang, Macromolecules 2000, 33, 243-245). An advantage of such compounds is the fact that they are bifunctional chain transfer agents, and a triblock copolymer can be formed in only two steps. The synthesis of such compounds is problematic, in particular for compounds comprising a tertiary A-group. A fourth type is a dithiocarbamate compound, wherein the Z-group represents N-(R')(R"), wherein one of the two groups R' and R" is an electron withdrawing group. Examples of such monofunctional alkoxycarbonyl dithiocarbamate compounds, viz. compounds in which one of R¹ and R2, or both, are hydrogen, are known from International application WO 99/35177. Although such compounds have a high transfer constant, it is a drawback of these compounds that the synthesis of compounds comprising several functional groups is not easy. An essential fact of all the aforesaid chain transfer agents is that the -C(=S)-Z-S- group remains present in the block copolymer that is formed, as a result of which an already formed copolymer itself can function as a chain transfer agent anew, which is characteristic of live polymerisation. Below a brief explanation of the RAFT process is given.

Initiation r M M IM P ⁱ n^* ,

Chain transfer

re-initiation

M M A^* AM ^* Pm k, k_p

chai n equ l i brati on

Fig. 1: Schematic representation of the proposed RAFT mechanism From the above Fig. 1 it will be apparent that all reactions are equilibriums, and that in said equilibriums each radical species can react with each "dormant" species or RAFT chain transfer agent. During the initiation process, a radical, I«, reacts with successive monomer units M so as to form a polymer radical P_n«. Step (a) shows the addition of the polymer radical P_n« to the initial RAFT chain transfer agent 1 for forming the intermediate radical 2. This intermediate radical 2 can fragment either into the two species from which it was formed, or into a "dormant" species 3 and a expelled radical A*. Step (b) shows the re-initiation of the polymerisation process through addition of the expelled radical A» to a monomer M, instead of the reversing reaction with 3 so as to form 1 (see (a)). This assumption is only realistic if A» is a good leaving group, which is capable of reinitiating polymerisation, i.e. I^MCA*] » k_β[3] [A»] . Step (c) shows the equilibrium between active, propagating chains and dormant chains 3 and 5 through the intermediate radical 4. A first important aspect with regard to controlling the reaction is that the exchange reaction (c) takes place rapidly in comparison with the propagation of the chain. As can be derived from the symmetrical structure of 4, no preference exists for a direction of fragmentation, and the chance that P_π« is formed is about as the same as the chance that P_m« is formed. If we assume that transfer takes place rapidly in comparison with propagation, the radical is rapidly exchanged between the chains and all chains have the same chance of adding monomers, and thus all chains will grow at the same rate during the same period of time. In addition to that it is important in connection with the final molecular weight distribution of the copolymer that all chains start to grow at the same time. To achieve this, the step from RAFT chain transfer agent 1 to dormant polymer species 3 would have to be rapid. In this reaction, the intermediate radical 2 is not symmetrical, and consequently group A must be selected such that it is a better homolytic leaving group than the (oligo er) polymer chain. In addition to that, the A-group must also be capable of re-initiating the polymerisation process. If this only happens slowly, it will result in a slow conversion of the transfer agent and thus in a widening of the molecular weight distribution. To ensure that all polymer chains carry a RAFT group up to a high degree of monomer conversion, the initiator concentration must be significantly lower than the concentration of the RAFT chain transfer agent, therefore. If the aim is to achieve polymers having a low polydispersity, the initiator concentration would have to be lower by a factor of at least 4 to 6 than the concentration of RAFT chain transfer agent. In other cases said initiator concentration would have to be much lower even, which leads to the problem of a very slow start of the reaction. A low radical concentration prevents definitive terminations through combination of two radicals. A reasonable middle course must be found, therefore. In the light of the above description, it is an object of the present invention to provide a method for obtaining multiblock copolymers which requires a minimum number of polymerisation steps. Another object of the present invention is to provide a polymerisation method in emulsion, such that an emulsion of the (multi)block copolymer is obtained that can be used directly. It is also an object of the present invention to use (linear) multifunctional chain transfer agents in a method for obtaining multiblock copolymers. In addition to that it is an object of the present invention to provide a method for the preparation of al oxycarbonyl dithiocarba ate-type chain transfer agents, wherein a high yield of the intended final product is realised and a wide selection of functional groups is possible. The present invention is characterized by multifunctional dithiocarboxylate compounds according to formula (I):

Z¹-(C(=S)-S-A-S-C(=S)-Z-)_n (I) wherein Z¹ has been selected from the group consisting of: -R' -OR', -C(=0)-H, -C(=0)-R', -C(=0)-0H, -C(=0)-0R', -0-C(=0)-H -0-C(=0)-R', -0-C(=0)-0H, -0-C(=0)-0R', -C(=0)-NH2, -C(=0)-N(H)-R' -C(=0)-N(R⁵)-R', -N(H)-R', -N(R⁵)-R', -N(H)~C(=0)-H, -N(R⁵)-C(=0)-H -N(H)-C(=0)-R', -N(R⁵)-C(=0)-R', -N(H)-C(=0)-0H, -N(R⁵)-C(=0)-0H -N(H)-C(=0)-0R', -N(R⁵)-C(=0)-0R', -N⁺(R⁵) (R⁶)-0^", -SH and -SR'; Z has been selected from the group consisting of: -R -[0]_k-R'-, -[C(=0)-]_k-R'-, -[_C(=0)-0]_k-R'-, -[0-C(=0)]_k-R -[0-C(=0)]_k-0R'-, -[C(=0)-N(H)]_k-R'-, -[C(=0)-N(R⁵)]_k-R'-, -[N(H)] R -[N(R⁵)] R'-, -N(H)-C(=0)-, -N(R⁵)-C(=0)-, -[N(H)-C(=0)]_k-R -[N(R⁵)-C(=0)]_k-R'-, -[N(H)-C(=0)-0]_k-R'-, - [N(R⁵)-C(=0) -0]_k-R' - -N⁺(R⁵)(R⁶)-0^"- and -[S]_k-R'-; A has been selected from the group consisting of: -CH₂-, -CIKR¹)-, -C^HR²)- and -C(R^J) (R²)-(L¹)_q-C(R³) (R⁴)-; n is an integer from 2 to 1000; R¹, R², R³ and R⁴ have been selected, independently of each other, from the group consisting of: -H, -R", -OR", -SR", -N(H)(R"), -CN, -I, -Br, -Cl and -F; R⁵ and R⁶ have been selected, independently of each other, from the group consisting of lower alkyl and lower aralkyl; L¹ has the same meaning as Z; q equals 0 or an integer from 1 to 100,000; k equals 1 or 2; R¹ has been selected from the group consisting of: alkyl, alkenyl, aryl, aralkyl, alkaryl, heteroaryl, (un)saturated carbocyclic group, aromatic carbocyclic group, (un) saturated heterocyclic group, aromatic heterocyclic group, organosilyl, organometal compound and polymer chain or one or more combinations thereof, whether or not substituted with one or more substituents SUB; R" has been selected from the group consisting of alkyl, alkenyl, aralkyl and organosilyl, whether or not substituted with one or more of the substituents SUB; substituents SUB have been selected, independently of each other, from the group consisting of: hydrogen, hydroxyl , alkoxy, acyl , acyloxy, carboxyl , carboxyl salt, sulphonyl, sulphonyl salt, alkoxycarbonyl, aryloxy-carbonyl , isocyanato, silyl, -CN, -I, -Br, -Cl , -F, amino, di alkyl amino and phosphoryl of one or more combinations thereof; on condition that if Z equals -SCH₂W-, wherein W has the same meaning as Z, A does not equal -CH₂- and -C(R) (R²)-(L¹)_q-C(R³) (R⁴)- in that case, and R¹, R², R³, R⁴ all equal -H. It is also possible to use other groups for Z¹ and Z, wherein the -c(=0)~ group is substituted for -C(=S)-, except for bonds to a nitrogen atom; in addition to that it is possible to substitute -OH or -OR¹ by -SH and -SR¹ groups. An example of a multifunctional dithiocarboxylate compound is known from a publication by Motokucho (S. Motokucho, A. Sudo, F. Sanda and T. Endo, Che . Co m. 2002, 1946-1947), viz. the one in which A equals -CH₂-p-phenyl-CH₂- and Z equals -SCH₂W-, wherein W is a piperazine ring, substituted on both nitrogen atoms. An advantage of the multifunctional dithiocarboxylate compound according to the invention is that very good experimental results, enabling an adequate control as regards the polydispersity, among other things, have been obtained. Preferably, n is an integer between 2 and 50, so as to obtain a dithiocarboxylate compound comprising 4 to 100 RAFT functionalities. It has been demonstrated that such compounds are easy to prepare and exhibit a very good control of the desired properties, such as a narrow polydispersity, of the polymers to be prepared therewith. It is in particular preferred for A to be equal to -C(R¹)(R²)-(L¹)_q-C(R³)(R⁴)-, wherein R¹, R², R³ and R⁴ do not equal -H. Such an A-group has two tertiary carbon atoms besides the dithiocarboxylate functions, which ensures that A is a better homolytic leaving group, as a result of which the aforesaid non-symmetrical intermediate radical 2 is preferably split up into dormant polymer species 3, so that all chains will start to grow at the same time, so that a narrower molecular weight distribution of the final copolymer, and thus a more uniform product, is obtained. A symmetrical chain transfer agent in which R¹ equals R³ and R² equals R⁴ is preferred for comparable reasons. To have the division of radicals into two groups take place at a comparable rate, it is advantageous if the radical is symmetrical. Preferably, R¹, R², R³ and R⁴ are all selected from the group of lower al yl and -CN. In this connection, lower alkyl is understood to be a group selected from the groups: methyl, ethyl, n-propyl , iso-propyl, n-butyl and sec-butyl. In particular methyl is preferred in view of possible steric interference when larger groups are used. In another preferred embodiment, R¹, R³ and R⁵ equal methyl, and R² and R⁴ equal -CN and q equals 0. The cyano group can stabilise the radical additionally through resonance structures. As already discussed in more detail above, in particular the al oxycarbonyl dithiocarbamate compounds, wherein Z equals -[N(R⁵)-C(=0)-0]₂-R'-, are preferred on account of the advantageous colour, odour and transfer constant properties, in particular with tertiary A-groups. An especially preferred compound prepared in accordance with the method described in Synthesis Example 3 is:

as it has been experimentally demonstrated that this makes it possible to obtain polymers that exhibit a good correlation with the predetermined properties of molecular weight and polydispersity. Such a linear mult functional chain transfer agent can be used in the preparation of multiblock copolymers, with only two polymerisation steps being required for obtaining the same. A more special chain transfer agent is a multifunctional chain transfer agent in which a polymer chain is already present, so that it is possible to form a multiblock copolymer in one single step or after one single monomer addition. In addition to said multifunctional chain transfer agents, the present invention also relates to bifunctional chain transfer agents, with only (n+l)/2 steps being required for preparing a block copolymer comprising n blocks. Accordingly, the present invention is characterized by a bifunctional dithiocarboxylate compound according to formula (II): Z²-C(=S)-S-B-S-C(=S)-Z³ (II) wherein B equals -C(R^J) (R²)-(L¹)_q-C(R³) (R⁴)-; Z² and Z3, independently of each other, have the same meaning as Z¹; and Z¹, R¹, R², R³, R⁴, L¹ and q are as defined in claim 1; on condition that if R¹, R², R³, R⁴ all equal methyl and L¹ equals p-phenyl and q equals 1. Z² and Z³ do not equal phenyl . An example of a bifunctional dithiocarboxylate compound, viz. the one in which B equals -CH(CH₃)-C(=0)-NH-CH₂-CH₂-NH-C(=0)-CH(CH₃)- and Z² and Z³ both equal phenyl, is known from the publication by Donovan

(M.S. Donovan, A.B. Lowe, T.A. Sanford, C.L. McCormick, Journal of

Polymer Science A, 2003, part 41, 1262-1281). The advantage of the bifunctional dithiocarboxylate compounds according to the present invention is that it is readily possible to prepare polymers exhibiting the predetermined structures and properties by means of said compounds. Preferably, this compound is symmetrical for the reasons that have been set forth above, and thus the two groups of one or more of the following pairs Z² and Z³, R¹ and R³ and R² and R⁴ are equal at all times. Furthermore, R¹, R², R³ and R⁴ are preferably selected from lower alkyl of -CN, in particular they are all methyl. The reason for such a preference as set forth above applies in this case as well. In another preferred embodiment, R¹, R³ and R⁵ equal methyl and R² and R⁴ equal -CN and q equals 0. The cyano group can stabilize the radical additionally by resonance structures. In this case too, the compound according to formula II is an alkoxycarbonyl dithiocarbamate, as described above. Two examples of bifunctional chain transfer agents prepared in accordance with the method of Synthesis Examples 1 and 2 are in particular preferred:

as it has been experimentally demonstrated that this makes it possible to obtain polymers that exhibit a good correlation with the predetermined properties of molecular weight and polydispersity. The present invention is further characterized by a monofunctional alkoxycarbonyl dithiocarbamate compound according to formula (III):

R'-C(=0)-N(R⁵)-C(=S)-S-C(R¹)(R²)-Z⁴ III wherein Z⁴ has the same meaning as Z¹; and Z¹, R¹, R², R⁵ and R' are as defined in claim 1. Examples of such monofunctional alkoxycarbonyl dithiocarbamate compounds, viz. compounds in which R¹ or R², or both, are hydrogen, are known from International application WO 99/35177. The aforesaid compounds have this drawback that they comprise a primary carbon atom besides the -C(=S)-S-group, as a result of which said groups are not satisfactory homolytic leaving groups. Consequently, the present monofunctional compound comprises a tertiary carbon atom at this position, thus enabling an improved control as regards the molecular architecture. In an especially preferred embodiment of the present invention, R¹ and R² both equal methyl, on account of the small size thereof, so that steric interference cannot occur during the polymerisation reaction. In another preferred embodiment of the present invention,

R¹ equals butyl, on account of the simplicity of this compound. The present invention is furthermore characterized by a method for the synthesis of compounds according to formulas (I), (II) and (III), wherein Z¹, Z² and Z³ equal -N(R)-C(=0)-0-R' ; and Z equals -N(R⁵)-C(=0)-0-R^'- R¹, R², R⁵, R¹ and Z⁴, are as defined in claims 1 and 21; which method comprises the steps of: a) reacting thio-urea, a halogen-containing acid, with one or more of the starting compounds according to formulas (IVa) and (IVb): HO-K-OH (IVa) HO-K (IVb) wherein K has been selected from the group consisting of A, B and

-C(R¹)(R²)-Z⁴; and A, B, R¹, R² and Z⁴ are defined in claims 1, 11 and 21; b) adding a base and R⁵-N=C=S, R⁵ being as defined in claim 1, to the mixture obtained in step a) to obtain one or more intermediate compounds according to formulas (Va) and (Vb):

H-N (R⁵) -C(=S) -S-K-S-C(=S) - (R⁵) -H (Va) H-N(R⁵)-C(=S)-S-K (Vb) c) reacting a phosgene or a derivative thereof with one or more of the starting compounds according to formulas (Via) and (VIb):

HO-R'-OH (Via) HO-R' (VIb) R¹ being as defined in claim 1. to obtain one or more intermediate compounds according to formulas (Vila) and (Vllb): Cl-C(=0)-0-R'-0-C(=0)-Cl (Vila) Cl-C(=0)-0-R' (Vllb) d) reacting one or more of the intermediate compounds according to formulas (Va) and (Vb) as obtained in step b) with one or more of the intermediate compounds according to formulas (Vila) and (Vllb) as obtained in step c) so as to obtain one or more of the compounds according to the formulas (I), (II) and (III). A method for the synthesis of a similar compound is known from International application WO 99/35177. A drawback of this method is the fact that it is not suitable for tertiary leaving groups (A) and for the incorporation of polymer chains. The advantage of the present invention is the fact that the desired compounds can be obtained by using commercially readily available, relatively inexpensive chemicals. The individual steps of this method are known per se to those skilled in the art, but the novel combination of these steps has led to an unexpectedly good result with these al oxycarbonyl dithiocarbamate compounds. A large variety of compounds can be synthesised with a large range of side groups. These groups may be low-molecular groups or high-molecular groups, such as polymer chains. Preferably, the halogenide-containing acid is selected from hydrogen bromide, hydrogen chloride or a combination thereof, wherein hydrogen bromide is especially preferred on account of the good reactivity it has been found to have. Possible combinations of one or more of said acids and other acids may also be used, of course. The base may be any base that is suitable for carrying out this reaction, preferably, however, it is a hydroxide, in particular sodium hydroxide, potassium hydroxide or calcium hydroxide. One or more combinations of these and other bases may also be used, of course. It is preferred to use onophosgene as the phosgene, because of its good reactivity. It is also possible, however, to use other phosgenes, such as diphosgene or triphosgene or other compounds, such as derivatives of phosgene in which the chlorine atom has been substituted by another group, such as a lactamate or comparable compounds with the same type of reactivity. The present invention is furthermore characterized by a method for the preparation by means of a radical polymerisation process of one or more polymers according to the formulas (VIII), (IX) and (X): Z¹-(C(=S)-S-(M^x)_a-A-(M^x)_a,-S-C(=S)-Z-)_n (VIII) Z²-C(=S)-S-(M^x)_a-B-(M^x)_a,-S-C(=S)-Z³ (IX) R'-C(=0)-N(R⁵)-C(=S)-S-(M^x)_a-C(R¹)(R²)-Z⁴ (X) comprising: contacting a radical source with: (i) monomer M^x; (ii) one or more chain transfer agents according to formulas (I), (II) and (III), under reaction conditions such that one or more polymers according to formulas (VIII), (IX) and (X) are obtained; wherein Z¹, A, Z and n are as defined in claim 1; Z², B and Z³ are as defined in claim 11; R', R⁵, R¹, R² and Z⁴ are as defined in claim 21; M^x equals one or more monomers selected from the group consisting of vinyl- and vinylidene monomers according to formula CH₂=CUV, maleic acid anhydride, N-alkyl maleimide, N-aryl malei ide, dialkyl fumarates and cyclopolymeri sable monomers or one or more combinations thereof; a and a', independently of each other, equal integers from 1 to 100,000; U and V, independently of each other, have the same meaning as Z¹, or have been selected independently of each other from -H, -CN, -F, -Cl, -Br, -I. The advantage of this method is that it is possible to use a very large number of monomers and combinations thereof, thus making it possible to prepare polymers having widely varying properties as desired. Another advantage of the present method is the fact that, using a multifunctional chain transfer agent, a multiblock copolymer can be obtained in one or two steps, as also explained in the foregoing. The present invention furthermore relates to a method for the preparation by means of a radical polymerisation process of one or more polymers according to the formulas (XI), (XII) and (XIII):

Z¹-(C(=S)-S-(M^y)_b-(M^x)_a-A-(M^x)_a,-(M^y)_b,-S-C(=S)-Z-)_n (XI) _Z ²-_C(=S)-S-(M^y)_b-(M^x)_a- B-(M^x)_a,-(M -S-C(=S)-Z³ (XII) R'-C(=0)-N(R⁵)-C(=S)-S-(M^y)_b-(M^x)_a-C(R¹)(R²)-Z⁴ (XIII) comprising: contacting a radical source with: (iii) monomer M^y; (iv) one or more polymers according to formulas (VIII), (IX) and (X), obtained in accordance with the method according to claim 28, under reaction conditions such that one or more polymers according to formulas (XI), (XII), (XIII) are obtained. where n W, independently of M^x, has the same meaning as M^x; b and b¹, independently of each other, are integers from 1 to 100,000. The present radical polymerisation process can be carried out in solution, wherein an organic solvent may be added so as to get and keep all components in one phase. The type of organic solvent is not specifically limited, as long as it is capable of dissolving the various components. Preferably, the present radical polymerisation process is carried out in emulsion, in particular in mini -emu! si on, which is a special variant of classical emulsion polymerisation. The advantages of using a classical emulsion polymerisation process in comparison with solution polymerisation are, among other things, the higher rate of polymerisation, the higher molecular weight that can be achieved, the higher rate of heat transfer and the relatively low viscosity of the reaction medium, which makes it easier to process the polymerisation. In addition to that, these water-based systems are more environmentally friendly, and the obtained emulsions of the copolymer can be used directly as a pressure-sensitive adhesive, so that the preparation thereof does not require an additional step. Emulsion polymerisation can be briefly described as follows. An emulsion is prepared from a mixture of water, a monomer, a surfactant and a water-soluble radical source. In the first phase, part of the monomer is dissolved in water, but the larger part is present in the form of large monomer droplets, stabilised by a surfactant. In addition to that, small, monomer-swollen micelles of the remaining surfactant are present. Radicals are generated in the aqueous phase and will react with water-dissolved monomer until a specific critical chain length has been reached, after which the particles become surface-active and penetrate the monomer-swollen micelles. This process is called particle nucleation. In said particles, the polymerisation process continues, fed by monomer that diffuses from the monomer droplets through the water to the particles. More and more particles or polymerisation places (loci) are formed until no micelles remain. Following that, the polymerisation process continues in the second phase, and the particles that are present continue to grow through polymerisation until all the monomer from the monomer droplets is used up and only polymer particles remain, therefore. Now the third and last phase begins, during which the remaining monomer in the particles is polymerised. The polymerisation rate now decreases constantly, on condition that no gel effect occurs. One of the important factors for successfully carrying out controlled radical polymerisation in emulsion is getting the deactivating compound into the locus of polymerisation. In this case, the deactivating compound is the RAFT chain transfer agent. Another important factor is allowing the nucleation to take place without interference when particles are being formed. During the first phase a high radical flux is desired so as to form a large number of particles and obtain a narrow particle size distribution. It will be apparent that this element conflicts with the requirement of a controlled radical polymerisation, which, on the contrary, requires a low radical flux. Another problem that occurs with emulsion in polymerisation is the escape of the "counter radical" from the particles, which causes the polymerisation process to be delayed and which has an adverse effect on the possibility to control the molecular weight and the polydispersity. There are a number of other known factors, which will not be specified herein, that render the use of emulsions in RAFT polymerisations very difficult. To solve the above problems, a variation on the emulsion polymerisation may be used, the so-called mini -emulsion polymerisation. This known method is different from the classical emulsion polymerisation in a number of essential points. The prefix "mini" relates to the size of the number droplets prior to polymerisation rather than to the particle size of the obtained latex. During mini-emulsion polymerisation, a co- stabiliser (usually a hydrophobic compound, such as hexadecane) is added to the monomer and the initial pre-emulsion is exposed to a very high shearing force, using a variety of possible techniques, so that small monomer droplets (50-500 nm) are obtained. The concentration of surfactant is kept below the critical micelle concentration so as to prevent secondary nucleation. As a result, however, there is a chance that the surface of the monomer droplets will not be entirely covered, which might lead to a reduced colloidal stability. After a radical source has been added, generated radicals react with monomers from the water layer in the first phase to form oligomeric radicals up to a specific critical chain length, after which the oligomeric radicals penetrate the monomer droplets. Ideally, all monomer droplets become particles in which polymerisation takes place (loci). A major advantage of mini-emulsion polymerisation in comparison with emulsion polymerisation is the fact that it can be used for forming composite particles, because additives, such as colorants, pigments and other water-insoluble materials can be added to the monomer prior to dispersion. After ho ogenisation of the pre-emulsion, said additives are evenly distributed over the monomer droplets and thus in the final latex to be obtained. As is the case with emulsion polymerisation, a number of problems, which will not be specified herein, are to be solved when using mini-emulsion polymerisation, but this method of polymerisation can be used in RAFT polymerisation. Preferably, sodium dodecyl sulphate (SDS) is used as the surfactant, on account of its good compatibility with the other reagents and its good experimental stability. It is also possible, however, to use other surfactants, such as other types of anionic surfactants, cationic surfactants, zwitter-ionic surfactants or non-ionic surfactants and one or more combinations thereof. Additives may be added advantageously during the mini- emulsion polymerisation so as to obtain a latex in which said additives are evenly distributed. Examples of such additives are colorants, pigments, UV stabilisers and the like. A large spectrum of other water- insoluble may be used, however. In the present polymerisation, either in solution or in emulsion, it is in particular preferred to use n-butyl acrylate, 2-ethyl- hexyl acrylate or iso-octyl acrylate or a mixture of n-butyl acrylate and (meth)acrylic acid as the first monomer and preferably iso-octyl acrylate as the second monomer, on account of the good results that have been obtained therewith, such as an excellent relation between the calculated molecular weight and the determined molecular weight, and also a good polydispersity and colloidal stability. A number of advantages and characteristics of the present invention will already be apparent from the above description. Other advantages will become apparent from the Synthesis Examples and Polymerisation Examples below. Briefly summarised, the important advantages of the invention include the fact that only two successive monomer additions are required for obtaining a multiblock copolymer. In addition to that, no escape of counter radical takes place when the min -emu! sion polymerisation method is used, which leads to an improved control of the reaction process and the final molecular weight of the polymer. No destabilisation of the obtained latex occurs during the mini-emulsion polymerisation, i.e. the latex is colloidally stable. In addition to that, the polymer that is formed by means of the present polymerisation method is substantially odourless and colourless, and the desired number of blocks can readily be determined. EXAMPLES SYNTHESIS EXAMPLE 1: preparation of bifunctional low- molecular chain transfer agent. Step Sl.l: Preparation of intermediate compound Va (S-(l,4-phenylenebis(propane-2,2-diyl)bis(N-methyl dithiocarbamate) (R²=Me, L=-C(CH₃)₂-phenyl-C(CH₃)₂-) Thiourea (17.2g, 0.23 mol) and α,α,α' ,α'-tetramethyl- 1,4-benzene dimethanol (20.0 g, 0.10 mol) were mixed and added to a flask of 250 ml with a 48%-solution of HBr (41.7 g, 0.25 mol) under slow stirring. The slurry thus obtained was heated to 50 °C in an oil bath for 5 minutes, after which the slurry became solid. The white solid was cooled, filtered, washed with 0.1 M aqueous Hbr solution and dried under vacuum. The solid thus obtained was ground to a white powder. A solution of NaOH (24.7 g, 0.62 mol) in water (50 ml) was heated to 40 °C in a 250 ml three-neck flask in an oil bath. The above obtained white powder was added to the NaOH-solution and the obtained mixture was stirred at 40 °C for two hours. A bright red solution was obtained. The solution was filtered over a Bϋchner funnel and the filtrate was transferred to a 250 ml three-neck flask provided with a dropping funnel and a cooler under an argon atmosphere. The solution was cooled to 5 °C, using an ice bath. Methyl isothiocyanate (15.8 g, 0.22 mol) was dissolved in a minimum amount of methanol and this solution was added dropwise to the red thiolate solution. The aforesaid desired product precipitated as a white solid. The obtained slurry was stirred for 1 hour to complete the reaction, and was subsequently filtered over a Buchner funnel and washed with cold water. The white solid was recrystallised twice from ethanol and dried under vacuum. The total yield was 60%. Hl-NMR: δ (ppm) 1.83 [s, 12H, C-(CH₃)₂]; 2.95 [d, 6H, NH-CH₃] ; 6.65 [s broad, 2H, N-H] ; 7.64 [s, 4H, aromatic H] . ¹³C-NMR: δ (ppm) 29.92 [C-CH₃]; 33.18 [NH-(CH₃)₂]; 54.37 [C-(CH₃)₂]; 127.27 (aromatic, 2-, 3-, 5-, 6-C); 143.96 (aromatic, 1-, 4-C) ; 196.01 (C=S) . LC-MS: 395.01 (MNa\ theoretically 395.072). Step SI.2: Preparation of intermediate compound Vllb: n-butyl chl orofor ate (R¹⁼butyl ) . The above compound can be obtained by using the method in Step S2.2 of Synthesis Example 2 below, in which butanol is used. It can also be commercially obtained, however, and be used directly in the following step. Step SI.3: Coupling of intermediate compounds Va and Vllb to obtain compound II, S-(l,4-phenylene bis(propane-2,2-diyl))- bis(N,N-butoxycarbonylmethyl dithiocarbamate) (Z²=Z³; R¹⁼n-Bu; R²=Me L=-C(CH₃)₂-phenyl-C(CH₃)₂-). N-butyl chl oroformate (3.1 g, 23 mmol), obtained in Step SI.2, was dissolved in THF (10 ml) in a double enveloped flask of 100 ml, provided with a stirrer and a dropping funnel of 50 ml. The solution was placed under an argon atmosphere and cooled to -20 °C by means of a cryostate. Intermediate compound Vllb (4.0 g, 11 mmol), obtained in the above Step Sl.l and triethylamine (5.4 g, 54 mmol) were dissolved in a minimum amount of THF. This solution was added dropwise to the n-butyl chloroformate-solution under stirring. The obtained mixture was stirred at -20 °C for 48 hours, after which the mixture was brought to room temperature. Triethylamine hydrochloride was filtered off and THF was removed under reduced pressure. The obtained yellow oil was purified by means of column chromatography, using dichloromethane as an eluent, providing the aforesaid desired product (II) in the form of a yellow solid with a yield of 85%. ^XH-NMR: δ(ppm) 0.92 [t, 6H, -0-CH₂-CH₂-CH₂-CH₃] ; 1.43 [m, 4H, -0-CH₂-CH₂- CH₂-CH₃]; 1.70 [ , 4H, -0-CH₂-CH₂-CH₂-CH₃] ; 1.88 [s, 12H, C-(CH₃)₂]; 3.51 [s, 6H, N-CH₃]; 4.26 [t, 4H, -0-CH₂-CH₂-CH₂-CH₃] ; 7.40 [s, 4H, aromatic H] . ¹³C-NMR: δ(ppm) 13.64 [-0-CH₂-CH₂-CH₂-CH₃] ; 19.12 [-0-CH₂-CH₂- CH₂-CH₃]; 28.83 [C-(CH₃)₂]; 30.52 [-0-CH₂-CH₂-CH₂-CH₃] ; 38.35 [C-(CH₃)₂]; 56.15 [N-CH₃]; 67.42 [-0-CH₂-CH₂-CH₂-CH₃] ; 126.05 [aromatic 2-, 3-, 5-, 6-C]; 142.84 [aromatic 1-, 4-C] ; 153.97 [C=0] ; 202.97 [C=S] . LC-MS: 595.76 (MNa⁺, theoretically 595.84). SYNTHESIS EXAMPLE 2: synthesis of bifunctional high- molecular chain transfer agent. Step S2.1: Preparation of intermediate compound Va

(S- (1 ,4-phenyl enebi s(propane-2,2-diyl ) bi s (N-methyl di thiocarbamate) (R²=Me, L=-C(CH₃)₂-phenyl -C(CH₃)₂-) . Step Sl.l of Synthesis Example 1 was repeated in order to obtain the aforesaid compound. Step S2.2: Preparation of intermediate compound Vllb, poly(butyl ene-co-ethyl ene) -chl oroformate (R¹⁼poly(butyl ene-co-ethyl ene) . A commercially available copolymer of ethyl ene and butyl ene comprising a terminal hydroxyl group (Kraton(brand) L-1203; M_n 4000 g/mol ; PDI 1.02) was used for synthetising intermediate compound Vllb, in which R¹ is a polymer chain is. To that end a 250 ml three-neck flask was provided with a stirrer, a 100 ml dropping funnel provided with a stopper and two septa provided with needles. The flask was placed under an argon atmosphere by means of the first septum, with the second septum being in communication with a washing bottle containing a 1 M aqueous NaOH- solution, for removing phosgene that escaped from the reaction vessel. A phosgene solution (2.5 g, 5.2 mmol) was injected into the flask through a septum. The flask was subsequently cooled to 0 °C in an ice bath. The aforesaid polymer (20.0 g, 5 mmol) was dissolved in toluene (30 ml) and the solution was transferred to the dropping funnel and slowly added to the phosgene solution. The mixture was stirred at 0 °C for 4 hours. The mixture was subsequently flushed with argon for 2 hours so as to remove excess phosgene, after which toluene was removed under a reduced pressure. The aforesaid desired intermediate product Vllb was obtained with a yield of 98% (calculated according to *H-NMR) and used without any further purification. Hl-NMR: δ(ppm) 0.80-1.80 [ , chain H] ; 4.36 [t, -CH₂-0(C0)C1] . ¹³C-NMR: δ(ppm) 10.60-39.20 [chain C] ; 71.16 [-CH₂-0(C0)C1] ; 151.10 [C=0] . Step S2.3: Coupling of intermediate compounds Va and Vllb to obtain compound II, S-(l,4-phenylenebis(propane-2,2-diyl)) bis(N,N-poly(butyl ene-co-ethyl ene)oxycarbonylmethyl dithiocarbamate) (Z²=Z³; R¹⁼poly(butyl ene-co-ethyl ene); R²=Me L=-C(CH₃)₂-phenyl-C(CH₃)₂-) . Intermediate compound Vllb (20.0 g, 5 mmol), obtained in the above Step S2.2, was dissolved in THF (30 ml) in a double enveloped 250 ml flask provided with a stirrer and a dropping funnel of 50 ml. The solution was placed under an argon atmosphere and cooled to -20 °C, using a cryostate. The intermediate compound Vb (0.9 g, 2.5 mmol) obtained in Step S2.1 and triethylamine (1.3 g, 13 mmol) were dissolved in a minimum amount of THF. This solution was added dropwise to the above-described solution comprising compound Vllb under stirring. The obtained mixture was stirred at -20 °C for 48 hours, after which the mixture was brought to room temperature. Triethylamine hydrochloride was filtered off and THF was removed under reduced pressure. The aforesaid desired product (II) was obtained with a yield of 86%. The viscous yellow oil that was obtained was not further purified and used as such in polymerisation reactions.

'H-NMR: δ(ppm) 0.80-1.80 [m, chain H] ; 1.96 [s, 12H, C-(CH₃)₂]; 3.57 [s, 6H, N-CH₃]; 4.35 [t, 4H, -0-CH₂-] ; 7.47 [s, 4H, aromatic H] . ¹³C-NMR: δ(ppm) 10.24-38.77 [chain C, C-(CH₃)₂]; 56.20 [N-CH₃] ; 67.78 [-0-CH₂-]; 126.10 [aromatic 2-, 3-, 5-, 6-C] ; 142.84 [aromatic 1-, 4-C]; 153.98 [C=0] ; 206.22 [C=S] . SYNTHESIS EXAMPLE 3: Multifunctional chain transfer agent Step SI.3: Preparation of intermediate compound Va (S-(l,4-phenylenebis(propane-2,2-diyl)bis(N-methyl dithiocarbamate) (R²=Me, L=-C(CH₃)₂-phenyl -C(CH₃)₂-) . Step Sl.l of Synthesis Example 1 is repeated to obtain the aforesaid compound. Step S3.2: Preparation of intermediate compound Vila, 1,10-decanediol-bischloroformate (R¹⁼decyl) . Intermediate compound Vila can be synthetised in accordance with the method described in Step S2.2 of Synthesis Example 2. The aforesaid desired compound is obtained with a yield of 98 % (calculated from Hl-NMR) 'H-NMR: δ(ppm) 1.20-1.90 [m, Cl (C0)0-CH₂-(CH₂)₈-CH₂-0(C0)C1] ; 4.38 [t, C1(C0)0-CH₂-(CH₂)₈-CH₂-0(C0)C1]. ¹³C-NMR: δ(ppm) 25.36-29.13 [Cl (C0)0~CH₂-(CH₂)₈-CH₂-0(C0)C1] ; 72.22 [Cl (C0)0-CH₂-(CH₂)₃-CH₂- 0(C0)C1]; 150.44 [C=0] . Step S3.3: Coupling of intermediate compounds Va and Vila to obtain compound I, poly(S-l,4-phenyl enebi s(propane- 2,2-diyl ) ) b s ( ,N-1, 10-decoxycarbonylmethyl di thiocarbamate) (R¹⁼decyl ; R²=Me L=-C(CH₃)₂-phenyl-C(CH₃)₂-; n=6) . Intermediate compound Vila (2.3 g, 11 mmol), obtained in Step S3.2, was dissolved in THF (10 ml) in a 100 ml double enveloped flask provided with a stirrer and a dropping funnel of 50 ml. The solution was placed under an argon atmosphere and cooled to -20 °C, using a cryostate. Intermediate compound Va (4.0 g, 11 mmol), obtained in Step S3.1, and triethylamine (6.7 g, 66 mmol) were dissolved in a minimum amount of THF. This solution was added dropwise to the aforesaid solution of intermediate compound Vila under stirring. The obtained mixture was stirred at -20 °C for 48 hours, after which the mixture was brought to room temperature. Triethyl amine-hydrochloride was filtered and THF was removed under reduced pressure. The viscous yellow oil that was obtained was further purified by means of preparative GPC. The product was obtained with a yield of 70%.

1H-NMR: δ(ppm) 1.20-2.10 [m, -(C0)0-CH₂-(CH₂)₈-CH₂-0(C0)-, C-(CH₃)₂]; 3.51 [s, N-CH₃]; 4.25 [t, -(C0)0-CH₂-(CH₂)₈-CH₂-0(C0)-] ; 7.40 [s, aromatic H] . ¹³C-NMR: δ(ppm) 22.63-32.42 [-(C0)0-CH₂-(CH₂)₈-CH₂-0(C0)- C- (CH₃)₂] ; 38.37 [C- (CH₃)₂] ; 56.14 [N-CH₃] ; 67.39 [- (C0) 0-CH₂- (CH₂) ₈-CH₂-

0(C0) -] ; 126.38 [aromati c 2- , 3- , 5- , 6-C] ; 142.97 [aromati c 1- , 4-C] ; 154.07 [C=0]; 203.12 [C=S] . GPC (prior to purification): M_n= 1800 g of moll, PDI= 1.80. GPC (after purification and isolation of the high- molecular fraction): M_n= 3700 g of moll, PDI= 1.59. ANALYSIS METHODS: NMR-analvsis: *H- and ¹³C-NMR-analysis were carried out, using a Varian Gemini -2000 300 MHz or a Varian Mercury-Vx 400 MHz spectrometer. Samples of the various compounds to be analysed were dissolved in CDC1₃. GPC analysis: GPC analysis was carried out, using a Waters model 510 pump, a model 410 refractive index detector (at 40 °C) and a model 486 UV detector (at 254 n ) in series. Injections were carried out by a Waters model WISP 712 auto-injector, using an injection volume of 50 μl. The columns used were a Plgel guard (5 μm particles) 50 x 7.5 mm column, followed by two Plgel mixed-C or mixed-D (5 μm particles) 300 7.5 mm columns at 40 °C in series. Tetrahydrofuran (stabilised with BHT) was used as an eluent with a flow rate of 1.0 ml/min. Calibration was carried out using polystyrene standards (Polymer Laboratories; M_n= 580 to

7.1 x 10⁶ g/mol). Data acquisition and processing was carried out, using Waters Millennium32 (v3.2 or 4.0) software. Before injections, the samples were filtered over a PFTE filter of 13 mm 0.2 μm, with a polypropylene housing (All tech). In the examples below, the following abbreviations are used: BA: n-butyl acrylate; BA:MAA: mixture of 90% BA and 10% methacryl c acid; D_n: number-averaged particle diameter; DGV: D_w/D_n: polydispersity of particle size distribution. 2-EHA; 2-ethylhexyl acrylate; i-OA: iso-octyl acrylate; KPS: potassium persulphate M_n det. : experimental ly determi ned number-averaged ol ecul ar wei ght M_n cal . : cal cul ated number-averaged mol ecul ar wei ght; PDI : M_w/M_n : polydi spersity of the mol ecul ar wei ght di stri buti on; SDS: sodiu dodecyl sulphate POLYMERISATION EXAMPLE 1: polymerisation reaction in solution, using bifunctional chain transfer agent. First step: homopolymerisation and copolymerisation in solution For the homopolymerisation, a mixture of 10.0 g monomer and 10.0 g of toluene was prepared in a three-neck flask provided with a reflux cooler. The chain transfer agent, synthetised in accordance with Synthesis Example 1, was added to this mixture in a amount of 2.0 x 10^"2 mol/1. This solution was flushed with argon for 45 minutes. The flask was heated in an oil bath of 80 °C. A solution of the radical source AIBN (final concentration in the total solution: 2.0 x 10^"3 mol/litre) in a small amount of toluene was injected into the reaction mixture. Samples were taken at regular intervals for gravimetric conversion measurements and GPC-analyses. The samples were quenched with hydroquinone and dried on a heating plate at 50 °C, followed by extensive drying at 50 °C in a vacuum oven. The same procedure was used for the copolymerisation, in this case, however, 2.0 g of a monomer mixture of BA and MAA and 2.0 g of toluene was used. The results are shown in Table 1 below. Both in the case of the homopolymerisation and in the case of the copolymerisation in solution, an excellent control of the molecular weight and the polydispersity was achieved. The experimental molecular weight and the calculated molecular weight correspond very well. In the case of the copolymerisation, a methacrylic acid incorporation in the polymer chain of 13.9% was measured by means of calibrated GPEC and acid-base titrations. It is apparent that this type of chain transfer agent can be used with a wide range of (acrylate) monomers. Table 1

Second step: homopolymerisation in solution to obtain a triblock copolymer. 5.0 g of monomer and 5.0 g of toluene were added to 10.0 g of reaction mixture as obtained in the above Step 1.1. Subsequently, the method as described in the above Step 1.1 was repeated, starting with argon flushing. An amount of AIBN was added (final concentration in solution: 2.0 x 10^"3 mol/1). This time, however, no chain transfer agent was added, after all, the solution from the preceding step is used for this purpose. The results are shown in Table 2 below. Table 2

Control of the block copolymerisation, starting from the polymers functional ised with chain transfer agent resulting from step 1, was excellent. The experimental molecular weight and the calculated molecular weight correspond very well in both cases. POLYMERISATION EXAMPLE 2: bifunctional low-molecular chain transfer agent in mini -e u! si on First step: homopolymerisation and copolymerisation in mini -emu! sion Preparation of the mini -emulsion: the bifunctional low- molecular chain transfer agent, obtained in Step S.1.3, was dissolved under stirring in a mixture of monomer (8.0 g, 20 wt.% latex) and hexadecane, which forms the organic phase. Sodium dodecyl sulphate (SDS) was dissolved in water (30 ml) to a final concentration of SDS of 2.3 x 10^"3 mol/1. The organic phase was added dropwise to the aqueous phase under vigorous stirring by a magnetic stirring device. The pre- emulsion was stirred vigorously for 1 hour, after which a sonication probe (400 W, Dr. Hielscher UP400 S) was introduced into the homogeneous mixture. The pre-emulsion was sonicated at an amplitude of 30% of the maximum force for 30 minutes without cooling. Hexadecane was added in a amount of 2 wt.% in relation to the acrylate. The concentration of the chain transfer agent in the organic phase ranged between 3.7 x 10^"2 and 4.4 x 10^'2 ol/1. After emu! si fi cation, the mini-emulsion was transferred to a double enveloped, 50 ml emulsion reactor provided with a reflux cooler and a thermocouple under an argon atmosphere. The mini-emulsion was stirred, using a magnetic stirring device, and heated to 70 °C. The radical source KPS was dissolved in a small amount of water and added to a final concentration in water of 3.0 x 10^"3 mol/1, and polymerisation was carried out under an argon atmosphere for three hours. Samples were taken at regular intervals for gravimetric conversion measurements and GPC analyses. The samples were quenched with hydroquinone and dried on a heating plate at 50 °C, followed by extensive drying in a vacuum oven at 50 °C. The results are shown in Table 3 below. Table 3

An excellent control of the molecular weight and the polydispersity was achieved with polymerisation in mini-emulsion, with homopolymerisation as well as with copolymerisation. In addition to that, the latex was colloidally stable during and after the polymerisation. Moreover, no secondary nucleation was established, which can be derived from the monomodal particle size d stribution. The experimental molecular weight and the calculated molecular weight correspond very well. In the case of copolymerisation, a methacrylic acid incorporation in the polymer chain of 9.2% was measured by means of calibrated GPEC and acid-base titrations. To enhance the incorporation of methacrylic acid, the pH of the latex was reduced from 6 to 2.5. It is apparent that this type of chain transfer agent can also be used in mini -emu! si on with a wide range of (acrylate) monomers. Second step: homopolymerisation in mini -emu! si on to obtain a triblock copolymer. The seed latices obtained in the above-described steps 2.1.1 -2.1.4 were diluted with de-ionised water and transferred to a reactor as described above. These latices were swollen with a fresh amount of monomer at room temperature during the night and stirred by means of a magnetic stirring device. Subsequently, the above-described methods of mini-emulsion-polymerisation were repeated, starting with argon flushing. In the above-described steps, 15 g of the seed latex was used. 3.0 g of iso-octyl acrylate was used as the monomer, and furthermore 12.0 g of water and the same amount of initiator as in the first step. The results are shown in Table 4 below. Table 4

A good control of the molecular weight was achieved during the block copolymerisation, with the latex produced in Step 2.1 being used as seed latex. During and after this emulsion polymerisation, the latex was colloidally stable. Moreover, no secondary nucleation was established, which can be derived from the monomodal particle size distribution. The relatively high polydispersity can be explained from the gelling effect that occurs in the case of a high monomer conversion. POLYMERISATION EXAMPLE 3: bifunctional high-molecular chain transfer agent in solution First Step: homopolymerisation in solution. The bifunctional high-molecular chain transfer agent, obtained in Step S2.3, was dissolved in a mixture of 10.0 g of n-butyl acrylate and 10.0 g of toluene to a final concentration of either 1.9 or 3.8 x 10^"2 mol/1. This was carried out in a three-neck flask, provided with a reflux cooler. This solution was subsequently flushed with argon for 45 minutes. The flask was heated to 80 °C in an oil bath. A radical source AIBN was dissolved in a small amount of toluene and injected through a septum to a final concentration of 1.9 x 10^"3 mol/1. Samples were taken at regular intervals for gravimetric conversion measurements, GPC analyses and MALDI-TOF MS- analyses. The samples were quenched with hydroquinone and dried on a heating plate at 50 °C, followed by extensive drying in a vacuum oven at 50 °C. The results of these polymerisations, using two different concentrations of chain transfer agent, are shown in Table 5 below. Table 5

The solution-polymerisation of n-butyl acrylate with a bifunctional high-molecular chain transfer agent took place in a properly controlled manner, although a small difference can be observed between the calculated molecular weight and the experimental molecular weight. This difference can be explained by the fact that the experimental molecular weight, determined by means of GPC, is overestimated on account of the presence of the polymer chains poly(ethylene-co-butylene) in the chain transfer agent. The molecular weight of these polymers is expressed in polystyrene equivalents, because the proper Mark-Houwit parameters for correcting the difference in the hydrodynamic volume between polystyrene and the aforesaid polymer are not available. This leads to an overesti ation of the experimental molecular weight. POLYMERISATION EXAMPLE 4: Bifunctional high-molecular chain transfer agent in mini -emulsion First step: homopolymerisation and copolymerisation in mini -emu! si on The bifunctional high-molecular chain transfer agent (2.0 g) , obtained in Step SI.3, was dissolved under stirring in a mixture of n-butyl acrylate (4.0 g) and toluene (4.0 g) , which forms the organic phase. For the aqueous phase, 4.6 x 10^"1 mol/liter SDS in 30.0 g of water was used. The organic phase was added dropwise to the aqueous phase under vigorous stirring by a magnetic stirring device. The pre-emulsion was stirred vigorously for one hour, after which a sonication probe (400 W, Dr. Hielscher UP400 S) was introduced into the homogeneous mixture. The pre-emulsion was sonicated at an amplitude of 30% of the maximum force without cooling for 30 minutes. After emu! si fi cation, the mini -emu! si on was transferred to a jacketed emulsion reactor provided with a reflux cooler and a thermocouple under an argon atmosphere. The mini -emu! si on was stirred by a magnetic stirring device and heated to 70 °C. A solution of radical source KPS in a small amount of water was added to a final concentration in the aqueous phase of 3.0 x 10^"3 mol/1, and polymerisation was carried out under an argon atmosphere. Samples were taken at regular intervals for gravimetric conversion measurements, GPC analyses. The samples were quenched with hydroquinone and dried on a heating plate at 50 °C, followed by extensive drying in a vacuum oven at 50 °C. The results are shown in Table 6 below. Table 6

The mini -emulsion-polymerisation of n-butyl acrylate with the bifunctional high-molecular chain transfer agent took place in a properly controlled manner. In this case, too, the difference between the calculated molecular weight and the experimental molecular weight can be explained by the fact that the experimental molecular weight of the polymer chain of the chain transfer agent cannot be accurately determined by means of GPC, because the required Mark-Houwit parameters are not known. Because of solubility problems of the chain transfer agent in butyl acrylate, small amounts of toluene were added to the organic phase. The latex was colloidally stable during and after the polymerisation, and no secondary nucleation was established, as can be derived from the monomodal particle size distribution. POLYMERISATION EXAMPLE 5: multifunctional chain transfer agent in solution. First step: homopolymerisation and copolymerisation in solution. The multifunctional chain transfer agent, obtained in Step S3.3, was dissolved in 10.0 g of a mixture of monomers, with 10 g toluene to a final concentration of the chain transfer agent of 7.0 x 10^"3 mol/1. The mixture was flushed with argon for 45 minutes and heated to 80 °C in an oil bath. The radical source AIBN was dissolved in a small amount of toluene and injected into the mixture to a final concentration of 3.3 x 10^"3 mol/1. Samples were taken at regular intervals for gravimetric conversion measurements and GPC analyses. The samples were quenched with hydroquinone and dried on a heating plate at 50 °C, followed by extensive drying in a vacuum oven at 50 °C. The results are shown in Table 7 below. Table 7

Second step: homopolymerisation in solution to obtain multiblock copolymer. The polymer obtained in the preceding step 5.1.1 was subjected anew to a radical polymerisation, using 10.0 g of the solution obtained in step 5.1.1, 5.0 g of iso-octyl acrylate and 5.0 g of toluene. The method of step 5.1 was repeated, with the total concentration of the radical source being 3.5 x 10^"3 mol/1. The results are shown in Table 8 below. Table 8

Although the polymerisation exhibits living characteristics, as represented by the increasing M_n with conversion, control as regards the polymerisation of acrylate monomers with the multifunctional chain transfer agent is not optimal. The difference between the experimental molecular weight and the calculated molecular weight can be explained by the reduction of the number of RAFT functions per polymer chain during the polymerisation reaction, on account of the relatively high radical flux. This leads to an number of blocks in the multiblock copolymer smaller than the calculated number of blocks and also to a lower number-averaged molecular weight. However, the principle of this method is demonstrated in this manner. POLYMERISATION EXAMPLE 6: multifunctional chain transfer agent in mini -emu! sion First step: homopolymerisation and copolymerisation in mini -e u! sion The multifunctional chain transfer agent, obtained from step S3.3, was dissolved under stirring in a mixture of 8.0 g of monomers (20 wt.% in relation to latex) and hexadecane (2 wt.% in relation to monomer) forming the organic phase. The total concentration of the chain transfer agent is 8.0 x 10^"3 mol/1. For the aqueous phase, a solution of 30.0 g of water and SDS in a concentration of 2.3 x 10^"3 mol/1 was prepared. The organic phase was added dropwise to the aqueous phase under vigorous stirring by a magnetic stirring device, after one hour, a sonication probe (400W Dr. Hielscher UP400S) was introduced into the heterogeneous mixture. The pre-emulsion was sonicated at an amplitude of 30% of the maximum force at room temperature for 30 minutes. After emu! s fi cation, the mini-emulsion was transferred to a jacketed emulsion reactor provided with a reflux cooler and a thermocouple under an argon atmosphere. The mini-emu! sion was heated to 70 °C and stirred, using a magnetic stirring device. A radical source KPS, dissolved in a small amount of water, was added in order to obtain a total concentration in the aqueous phase of 2.5 x 10^"3 mol/1. The polymerisation was carried out under an argon atmosphere. Samples were taken at regular intervals for gravimetric conversion measurements and GPC-analyses. The samples were quenched with hydroquinone and dried on a heating plate at 50 °C, followed by extensive drying in a vacuum oven at 50 °C. The results are shown in Table 9 below. Table 9

Second step: homopolymerisation in mini-emulsion to obtain a multiblock copolymer. 15 g of the latex obtained in the above step 6.1 was diluted with 12.0 g of water, and this latex was swollen with 3.0 g of iso-octyl acrylate at room temperature during the night. Subsequently, the method described in the above step 6.1 was repeated, starting by flushing of argon through the solution. Following that, the multiblock copolymer thus formed was analysed by means of GPC. The results of the obtained latex are shown in Table 10 below. Table 10

The level of control achieved in the case of the mini- emulsion polymerisation of acrylate monomers with the multifunctional chain transfer agent was significantly better than in the case of the solution polymerisation (Example 5). In the mini -emu! si on polymerisation- experiments, the radical flux is lower than in the solution polymerisation experiments. As a result, the difference between the experimental molecular weight and the calculated molecular weight is much smaller. The number of blocks in the multiblock copolymer in the obtained latex corresponds fairly well with the calculated number of blocks in the multiblock copolymer. Analysis methods for polymerisation-experiments. GPC analysis GPC analysis was carried out, as also described in the above Synthesis Examples. Measurements of the particle size: the diameters of the particles were measured on a LS 32 Coulter counter, and for this purpose the samples were first diluted with deionised water. Calibrated GPEC (gradient-polymer elυtion chromatography) : GPEC-analysis was carried out by using an Agilent Technologies 1100 system, using a G1311A quaternary pump, a G1313A automatic sampler, a G1315B UV diode array detector at 254 nm and a S.E.D.E.R.E. SEDEX 55 ELSD (evaporative light scattering detector), at a pressure of 2.2 bar and a temperature of 60 °C. The obtained data were processed, using HP chemstation software. The Zorbax C-18 was used, with a gradient being used as an eluent in 20 minutes, starting with a mixture of THF (HPLC purity) and water (80:20) and ending with only THF. The flow rate was 1.0 ml/min at 25 °C. Samples were prepared as solutions in THF with a concentration of 10 mg/ml , with in particular 10 μl being injected. Acid-base titrations: for the titrations, the copolymers to be measured were precipitated from methanol and dried in a vacuum oven. 0.1 g of copolymer dissolved in 150 ml THF/water (80:20). The obtained solution was acidified with 0.1 ml IN HC1. Na equilibration of 30 minutes the mixture was titrated with the addition of 1 ml of 0.01 N sodium hydroxide by means of a Metroh 665 Dosimat every 30 seconds. The pH was measured with a pH-electrode, which is suitable for non-aqueous solutions. Each copolymer was titrated three times, with the values shown in the text being an average of these three values.

Claims

1. Multifunctional dithiocarboxylate compound according to formula (I):

Z¹-(c(=S)-S-A-S-C(=S)-Z-)_π (I)

wherein Z¹ has been selected from the group consisting of: -R'

-OR', -C(=0)-H, -C(=0)-R', -C(=0)-0H, -C(=0)-0R', -0-C(=0)-H -0-C(=0)-R\ -0-C(=0)-0H, -0-C(=0)-0R', -C(=0)-NH₂, -C(=0)-N(H)-R' -C(=0)-N(R⁵)-R', -N(H)-R', -N(R⁵)-R', -N(H)~C(=0)-H, -N(R⁵)-C(=0)-H -N(H)-C(=0)-R', -N(R⁵)-C(=0)-R', -N(H)-C(=0)-0H, -N(R⁵)-C(=0)-0H -N(H)-C(=0)-0R", -N(R⁵)-C(=0)-0R', -N⁺(R⁵) (R -0^', -SH and -SR'; Z has been selected from the group consisting of: -R'- -[0]_k-R'-, -[_C(=0)-]_k-R'-, -[C(=0)-0]_k-R'-, -[0-C(=0)]_k-R'- _[0-C(=0)]_k-0R'-, -[C(=0)-N(H)]_k-R'-, -[C(=0)-N(R⁵)]_k-R'-, -[N(H)]_k-R'- -[N(R⁵)]_k-R'-, -N(H)-C(=0)-, -N(R⁵)-C(=0)-, _[N(H)-C(=0)]_k-R' - -[N(R⁵)-C(=0)]_k-R'-, -[N(H)-C(=0)-0]_k-R'-, -[N(R⁵)-C(=0)-0]_k-R' - -N⁺(R⁵)(R⁶)-0^"- and -[S]_k-R'-; A has been selected from the group consisting of: -CH₂-, -OUR¹)-. ^^(R²)- and -C(R^X) (R²)-(L¹)_q-C(R³) (R⁴)-; n is an integer from 2 to 1000; R¹, R², R³ and R⁴ have been selected, independently of each other, from the group consisting of: -H, -R", -OR", -SR", -N(H)(R"), -CN, -I, -Br, -Cl and -F; R⁵ and R⁶ have been selected, independently of each other, from the group consisting of lower alkyl and lower aralkyl; L¹ has the same meaning as Z; q equals 0 or an integer from 1 to 100,000; k equals 1 or 2; R' has been selected from the group consisting of: alkyl, alkenyl, aryl, aralkyl, alkaryl, heteroaryl, (un) saturated carbocyclic group, aromatic carbocyclic group, (un) saturated heterocyclic group, aromatic heterocyclic group, organosilyl, organometal compound and polymer chain or one or more combinations thereof, whether or not substituted with one or more substituents SUB; R" has been selected from the group consisting of alkyl, alkenyl, aralkyl and organosilyl, whether or not substituted with one or more of the substituents SUB; substituents SUB have been selected, independently of each other, from the group consisting of: hydrogen, hydroxyl , alkoxy, acyl , acyloxy, carboxyl, carboxyl salt, sulphonyl, sulphonyl salt, alkoxy- carbonyl , aryloxy-carbonyl , isocyanato, silyl, -CN, -I, -Br, -Cl , -F, amino, di alkyl ami no and phosphoryl of one or more combinations thereof; on condition that if Z equals -SCH₂W-, wherein W has the same meaning as Z, A does not equal -CH₂- and -C(R^X) (R²)-(L¹)_q-C(R³) (R⁴)- in that case, and R¹, R², R³, R⁴ all equal -H.

2. A compound according to claim 1, characterized in that n is an integer from 2 to 50.

3. A compound according to any one or more of the preceding claims, characterized in that A equals -C(R¹) (R²)-(L¹)_q-C(R³) (R⁴)-, and R¹, R², R\ R⁴ do not equal -H.

4. A compound according to claim 3, characterized in that R¹ equals R³ and that R² equals R⁴.

5. A compound according to any one or more of the preceding claims, characterized in that R¹, R², R³, R⁴ have been selected, independently of each other, from the group consisting of: lower alkyl and -CN.

6. A compound according to claim 5, characterized in that R¹, R², R³, R⁴ all equal methyl.

7. A compound according to claim 5, characterized in that R¹, R³, R⁵ equal methyl and that R² and R⁴ equal -CN and that q equals 0.

8. A compound according to any one or more of the preceding claims, characterized in that Z equals -[N(R⁵)-C(=0)-0]₂-R'-.

9. A compound according to claims 8, characterized in that R¹, R², R³, R⁴, R⁵ all equal methyl, that L¹ equals p-phenyl, that q equals 1 and R' equals decyl .

10. A compound according to claims 8, characterized in that R¹, R², R³, R⁴, R⁵ all equal methyl, that L¹ equals p-phenyl, that q equals 1 and that R' equals poly(butylene-co-ethylene) .

11. A bifunctional dithiocarboxylate compound according to formula (II)

Z²-C(=S)-S-B-S-C(=S)-Z³ (II) wherein B equals -C(R^X) (R²)-(L¹)_q-C(R³) (R⁴)-; Z² and Z³, independently of each other, have the same meaning as Z¹; and Z¹, R¹, R², R³, R⁴, L¹ and q are as defined in claim 1; on condition that if R¹, R², R³, R⁴ all equal methyl and L¹ equals p-phenyl and q equals 1. Z² and Z³ do not equal phenyl .

12. A compound according to claim 11, characterized in that Z² equals Z³.

13. A compound according to any one or more of the claims 11-12, characterized in that R¹ equals R³.

14. A compound according to any one or more of the claims 11-13, characterized in that R² equals R⁴.

15. A compound according to any one or more of the claims 11-14, characterized in that R¹, R², R³, R⁴ have been selected, independently of each other, from the group consisting of lower alkyl and -CN.

16. A compound according to claim 15, characterized in that R¹, R², R³, R⁴ all equal methyl.

17. A compound according to claim 15, characterized in that R¹, R³, R⁵ equal methyl, that R² and R⁴ equal -CN and that q equals 0.

18. A compound according to any one or more of the claims 11-17, characterized in that Z² and Z³ both equal -N(R⁵)-C(=0)-0R' , R⁵ and

R¹ being as defined in claim 1.

19. A compound according to claim 18, characterized in that R¹, R², R³, R⁴, R⁵ all equal methyl, that L¹ equals p-phenyl, that q equals 1 and that R' equals butyl.

20. A compound according to claims 18, characterized in that R¹, R², R³, R⁴, R⁵ all equal methyl, that L¹ equals p-phenyl, that q equals 1 and that R¹ equals poly(butylene-co-ethylene) .

21. A monofunctional alkoxycarbonyl dithiocarbamate compound according to formula III

R'-C(=0)-N(R⁵)-C(=S)-S-C(R¹)(R²)-Z⁴ III wherein Z⁴ has the same meaning as Z¹; and Z¹, R¹, R², R⁵ and R' are as defined in claim 1.

22. A compound according to claim 21, characterized in that R¹ and R² both equal methyl .

23. A compound according to any one or more of the claims 21-22, characterized in that R¹ equals butyl.

24. A method for the synthesis of compounds according to formulas (I), (II) and (III), wherein Z¹, Z² and Z³ equal -N(R⁵)-C(=0)-0-R' ; and Z equals -N(R⁵)-C(=0)-0-R^'- R¹, R², R⁵, R' and Z⁴, are as defined in claims 1 and 21; which method comprises the steps of: a) reacting thio-urea, a halogen-containing acid, with one or more of the starting compounds according to formulas (IVa) and (Ivb):

HO-K-OK (IVa) HO-K (IVb) wherein K has been selected from the group consisting of A, B and -C(R^X)(R²)-Z⁴; and A, B, R¹, R² and Z⁴ are as defined in claims 1, 11 and 21; b) adding a base and R⁵-N=C=S, R⁵ as as defined in claim 1, to the mixture obtained in step a) to obtain one or more intermediate compounds according to formulas (Va) and (Vb) : H-N(R⁵)-C(=S)-S-K-S-C(=S)-N(R⁵)-H (Va) H-N(R⁵)-C(=S)-S-K (Vb) c) reacting a phosgene or a derivative thereof with one or more of the starting compounds according to formulas (Via) and (VIb):

HO-R'-OH (Via) HO-R¹ (VIb) R' being as defined in claim 1, to obtain one or more intermediate compounds according to formulas (Vila) and (Vllb): Cl-C(=0)-0-R'-0-C(=0)-Cl (Vila) Cl-C(=0)-0-R' (Vllb) d) reacting one or more of the intermediate compounds according to formulas (Va) and (Vb) as obtained in step b) with one or more of the intermediate compounds according to formulas (Vila) and

(Vllb) as obtained in step c) so as to obtain one or more of the compounds according to the formulas (I), (II) and (III).

25. A method according to claim 24, characterized in that said halogen-containing acid is selected from hydrogen bromide, hydrogen chloride or a combination thereof.

26. A method according to any one or more of the claims 24-25, characterized in that said base is selected from sodium hydroxide, potassium hydroxide and calcium hydroxide or one or more combinations thereof.

27. A method according to any one or more of the claims 24-26, characterized in that said phosgene is onophosgene.

28. A method for the preparation by means of a radical polymerisation process of one or more polymers according to the formulas (VIII), (IX) and (X):

Z¹-(C(=S)-S-(M^x)_a-A-(M^x)_a,-S-C(=S)-Z-)_n (VIII) Z²-C(=S)-S-(M^x)_a-B-(M^x)_a,-S-C(=S)-Z³ (IX) R'-C(=0)-N(R⁵)-C(=S)-S-(M^x)_a-C(R¹)(R²)-Z⁴ (X) comprising: contacting a radical source with: (i) monomer M^x; (ii) one or more chain transfer agents according to formulas (I), (II) and (III), under reaction conditions such that one or more polymers according to formulas (VIII), (IX) and (X) are obtained; wherein Z¹, A, Z and n are as defined in claim 1; Z², B and Z³ are as defined in claim 11; R', R⁵, R¹, R² and Z⁴ are as defined in claim 21; M^x equals one or more monomers selected from the group consisting of vinyl- and vinylidene monomers according to formula CH₂=CUV, maleic acid anhydride, N-alkyl maleimide, N-aryl maleimide, dialkyl fumarates and cyclopolymeri sable monomers or one or more combinations thereof; a and a¹, independently of each other, equal integers from

1 to 100,000; U and V, independently of each other, have the same meaning as Z¹, or have been selected, independently of each other, from -H, -CN, -F, -Cl, -Br, -I.

29. A method for the preparation by means of a radical polymerisation process of one or more polymers according to the formulas (XI), (XII) and (XIII):

Z¹-(C(=S)-S-(M^y)_b-(M^x)_a-A-(M^x)_a,-(M^y)_b,-S-C(=S)-Z-)_n (XI) Z²-C(=S)-S-(M^y)_b-(M^x)_a- B-(M^x)_a,-(M -S-C(=S)-Z³ (XII) R^,-C(=0)-N(R⁵)-C(=S)-S-(M^y)_b-(M^x)_a-C(R¹)(R²)-Z⁴ (XIII) comprising: contacting a radical source with: (iii) monomer M^y; (iv) one or more polymers according to formulas (VIII), (IX) and (X), obtained in accordance with the method according to claim 28, under reaction conditions such that one or more polymers according to formulas (XI), (XII), (XIII) are obtained, wherein M^y, independently of M^x, has the same meaning as M^x; b and b¹, independently of each other, are integers from 1 to 100,000.

30. A method according to any one or more of the claims 28-29, characterized in that said radical polymerisation is carried out in solution.

31. A method according to any one or more of the claims 28-29, characterized in that said radical polymerisation is carried out in emulsion.

32. A method according to claims 31, characterized in that said radical polymerisation is carried out in mini -emulsion.

33. A method according to any one or more of the claims 31-32, characterized in that sodium dodecyl sulphate is used as the surfactant.

34. A method according to any one or more of the claims 31-33, characterized in that one or more water-insoluble additives selected from the group consisting of colorants, pigments and UV-absorbing agents and one or more combinations thereof are added.

35. A method according to any one or more of the claims 28 and

30-34, characterized in that M^x is n-butyl acrylate.

36. A method according to any one or more of the claims 28 and 30-34, characterized in that M^x is 2-ethylhexyl acrylate.

37. A method according to any one or more of the claims 28 and 30-34, characterized in that M^x is iso-octyl acrylate.

38. A method according to any one or more of the claims 28 and 30-34, characterized in that M^x is a mixture of n-butyl acrylate and acrylic acid.

39. A method according to any one or more of the claims 29-38, characterized in that M^y is iso-octyl acrylate.

40. Use of one or more polymers according to the formulas (VIII), (IX), (X), (XI), (XII) and (XIII) as a pressure-sensitive adhesive.

41. Use of one or more polymers according to the formulas (VIII), (IX), (X), (XI), (XII) and (XIII) as a compatibi liser for polymer mixtures and composites.

42. Use of one or more polymers according to the formulas (VIII), (IX), (X), (XI), (XII) and (XIII) as an impact modifying agent for thermoplastic elastomers.

43. Use of one or more polymers according to the formulas (VIII), (IX), (X), (XI), (XII) and (XIII) as a hot-melt.

44. Use of one or more polymers according to the formulas (VIII), (IX), (X), (XI), (XII) and (XIII) for imaging applications.