TECHNOLOGY FOCUS - POLYMERS - Preparation (claimed): Preparation of (P1) (where the hydrocarbon backbone carries COOH side groups, 3-20C aliphatic moieties having 0-3 heteroatoms selected from N, O, S, Se or Si, and 3-80C aliphatic moieties having 2-40 heteroatoms selected from N and O, and copolymerizable group) involves reacting in a solvent, a maleic anhydride polymer of formula (I), with a monofunctional compound having 3-20C alkyl chain and 0-2 heteroatoms selected from N, O, S, Se and Si, where the functional group of the monofunctional compound is capable of forming a linkage with an anhydride, and bifunctional compound having 3-80C alkyl chain and 0-40 heteroatoms selected from N and O. One functional group of the bifunctional compound is capable of forming a linkage with an anhydride, and another functional group of the bifunctional compound is copolymerizable, where only the functional group of the bifunctional compound capable of forming a linkage with an anhydride is allowed to react with (I).n=10-10000 (preferably 32);andR1=H or methyl.Preferred Process: The functional group of the monofunctional compound is an amino, hydroxyl, thiol, selenol, halogen, ether or thioether group (preferably 5-15C alkyl chain having 0-2 heteroatoms, especially alkylamine, particularly n-octylamine). The copolymerizable functional group of the bifunctional compound is an amino, hydroxyl, group containing terminal C=C bond, allyl, allyl glycidyl ether, epoxide, oxetane, internal C=C bond, terminal C?=C group, internal C?=C group, terminal coupled -C=C-C=C- group or their substituted derivatives (preferably terminal C=C bond from vinyl or acryl group). The functional group of the bifunctional compound that is capable of forming a linkage with an anhydride is different from its copolymerizable functional group. The bifunctional compound is polyethyleneglycol (PEG) or diaminoalkyl-polyethyleneglycol (preferably PEG 600 or diaminopropyl PEG, especially PEG(NH2)2 1500). The bifunctional compound is a vinylic amine, hydroxyl alkyl acrylic ester or an amino alkyl acrylic amide (preferably 2-propen-1-amine or aminopropyl vinyl ether). The process is carried out in the presence of a base (preferably non nucleophilic base selected from lithium diisopropylamide, lithium tetramethylpiperidine, diisopropylethyl amine (Hunig's base), 1,5-diazabicyclo(4.3.0)-non-5-ene, 1,8-diazabicyclo(5.4.0)undec-7-ene, bis(trimethylsilyl)amide, hexamethyldisilazane or bismesitylmagnesium). Preferred Polymer: The polymer (P1) is of formula (II).m, o and p=3-400 (preferably 3-40);m+o+p=10-10000 (preferably 32);R2=3-20C aliphatic chain having 0-3 heteroatoms selected from N, O, S, Se or Si (preferably n-octylamino);andR3=3-80C aliphatic chain having 0-40 heteroatoms selected from N or O, and a copolymerizable group (preferably PEG(NH2)2 1500).The ratio of p/(m+o) is 0-20 (preferably 1). Preferred Method: In method (M1), the nanocrystal comprises a semiconducting material. The semiconducting material comprises at least one metal and metalloid. The nanocrystal is soluble in non-polar solvents. The nanocrystal comprises on its surface via non-covalent interaction a coordinating solvent that comprises aliphatic side chains. At least a portion of the coordinating solvent is exchanged for (P1). The non-covalent or covalent interaction between (P1) and the nanocrystal is a coordinative bond, a Casimir interaction, a hydrophobic interaction, hydrogen bonding, a solvation force or Van-der-Waals interaction. The solvent in which the nanocrystal is provided is an aprotic solvent or aprotic non-polar solvent (preferably mineral oil, hexane, heptane, cyclohexane, benzene, toluene, pyridine, dichloromethane, chloroform, carbon tetrachloride, carbon disulfide, dioxane, diethyl ether, diisopropylether, ethylene glycol monobutyl ether or tetrahydrofuran). The solvent in which the nanocrystal is provided is removed after non-covalent or covalent interaction between (P1) and the nanocrystal has been allowed to occur. (P1) is added to the nanocrystal in the solvent. (P1) is provided in a polar solvent (preferably polar protic solvent, especially water). (M1) further involves allowing the copolymerizable groups of the second aliphatic moieties of (P1) to be crosslinked by reacting (P1) with a bifunctional (monomeric) compound, where at least two functional groups of bifunctional (monomeric) compound are capable of forming a linkage with the copolymerizable groups of the second aliphatic moieties of (P1). The functional groups of the bifunctional (monomeric) compound is amino, hydroxyl, thiol, selenol, halogen, ether, thioether, epoxy, nitro, trihalosilyl, terminal C=C bond or terminal C?=C bond. The bifunctional compound is water soluble. The bifunctional (monomeric) compound is N-vinylpyrolidone, acrylic acid, acrylic acid ester, acrylic acid amide (preferably N-isopropylacrylamide) or vinyl ether derivate. (P1) is reacted with bifunctional compound in a polar protic solvent (preferably water). In (M1), the crosslinking is effected by allowing the copolymerizable groups of the second aliphatic moieties of (P1) to cross-polymerize with each other, without adding a (monomeric) bifunctional compound. The crosslinking involves adding a initiator, and allowing the formation of a polymeric meshwork with several embedded water-soluble nanocrystals in it. The amount of nanocrystals in (P1) is 0.01-50 vol./vol.%. (P1) has on its surface side chains having 3-80C alkyl chain, 0-40 heteroatoms selected from N and O, and a copolymerizable group. The copolymerizable groups of the second aliphatic moieties are crosslinked by copolymerization with an at least bifunctional compound. The copolymerizable groups of the second aliphatic moieties are crosslinked by cross-copolymerization with each other. The copolymerizable group is an amino, hydroxyl or group containing a terminal C=C bond, for the formation of a polymer meshwork. The copolymerizable group is a head group of the side chain. The nanocrystals are embedded in the polymer meshwork via non-covalent or covalent interaction between (P1) and the nanocrystal. The polymer meshwork is obtained by allowing the copolymerizable groups of the second aliphatic moieties of (P1) to be crosslinked. EXAMPLE - No suitable example given.