US 2017/0170505 Al  3  Jun. 15,2017  $^{29 }$Sekine, M.; Hata. T.  J Chem.  Soc.  Chem Commun.  1978, 285  $^{30 }$Lecouvey, M.; Leroux, Y.  Heteroatom Chem.  2000, 11(7), 556-561  $^{31 }$Sekine, M.; Okimoto, K.; Yamada, K.; Hata, T.  J. Org. Chem.  1981, 46,  2097-2107  $^{32 }$Guenin. E.; Degache. E.; Liquier, J.; Lecouvey, M.  Eur. J. Org. Chem.  2004, 2983-2987  [0046]  A special embodiment of these blends is that  between the polymers and the low molecular phosphonic  acids ionic cross-links may be formed, for instance between  the cation exchange groups of the polymer with a basic  group (e.g. pyridine moiety) of the low molecular phospho› nic acid compound, see FIG.  8.  Another possibility of  bonding of the low molecular hydroxymethylenephosphonic  acids on the polymers is a covalent cross-link, for instance  by crosslinking of the OH-group of the phosphonic acid  compoand with an OH-group of the polymer via a ’v’,T› dihalogene alcane, see FIG.  9.  Other possible cross-linking  reactions for the OH-group of the l-hydroxymethylene-1,1- bisphosphonic acid group and if necessary with OH-groups  of polymers according to the invention are:  [0054]  Covalent cross-linking prevents diffusion of the  phosphonic acid compound out of the polymer and increases  the mechanical stability of the blended films.  [0055]  By the above described covalent cross-linking pro› cesses interpenetrating network (IPN) of the most different  structure and composition can be formed. An example of this  follows below. Exemplarily the following components are  dissolved in an aprotic solvent such as N-methylpyrrolidone  (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethyl› formamide (DMF) or dimethylsulfoxide (DMSO): a poly› mer with sulfochloride groups, a cross-linker for sulfochlo› ride  groups  like  4,4’-diaminodiphenylsulfone 40 ,  a  bifunctional  l-hydroxymethylene-1, 1-bisphosphonic acid  like 1,4-bis(l-hydroxymethylene-1,1-bisphosphonic acid)  benzene and a cross-linker for the OH groups of l-hy› droxymethylene-1,1-bisphosphonic acid like glutaralde› hyde. After making  a homogeneous  solution of all  components, it is coated on a support with a doctor knife and  the solvent is evaporated. An IPN is formed from the  network of sulfochlorated polymer with difunctional amine  and the network of 1,4-bis(l-hydroxymethylene-l, 1-bispho› sphonic acid)benzene and glutaraldehyde, that can be post› treated by mineral acid (0,1 to 80% H$_{2}$SO$_{4}$ , 0,1 to 37% HCl  or 0,1 to 85% phosphoric acid) and if necessary storage in  water to remove an excess of mineral acid. An example of  a hybride polymer network (HPN) is for example: in a  dipolar-aprotic solvent (see above) the following compo› nents are dissolved: a polymer with sulfonate groups  (-SO$_{3}$Me) and sulfinate groups (-SO$_{2}$Me) in the salt form  with Me representing alkali metal cation, earth alkali metal  cation, any ammonium ion, Ag+-Ion, 3-(1-hydroxy-l,1-bis› phosphonic acid)-pyridine, a a,w-dihalogene alcane like  1,4-diiodine butane as cross-linker for the sulfinate groups  (S-alkylation of the sulfinate groups 41 ) and as cross-linker  for the OH groups of l-hydroxymethylene-1,1-bisphospho› nic acid groups e.g. glutaraldehye 36 . After making a homo› geneous solution of all components, it is coated on a support  with a doctor blade and the solvent is evaporated. The  formed HPN can be posttreated as follows: 1. Post-treatment  in mineral acid (0,1 to 80% H$_{2}$ SO$_{4}$ ,  0,1 to 37% HCl or 0,1  to 85% phosphoric acid) and if necessary 2. subsequent  storage in water to remove an excess of mineral acid. The  formed HPN consists of a covalent network of the polymer  with sulfinate and sulfonate groups 42 , whereby the sulfinate  groups are cross-linked by S-alkylation with 1,4-diiodine  butane and the network of 3-(1-hydroxy-l, 1-bisphosphonic  acid)-pyridine and glutaraldehyde. In addition ionic inter› actions exist between both networks between the pyridine  groups of 3-(1-hydroxy-l, 1-bisphosphonic acids )-pyridins  and the sulfonate groups of the sulfonated polymer. Also the  1,4-diiodine butane cross-linker can cross-link also a part of  the pyridine groups by alkylation, whereby mixed cross› linking bridges between the sulfinate groups and the pyri› dine groups are formed 43 .  $^{40 }$R. Nolte. K. Ledjeff, M. Bauer, R. Miilhaupt, R.,  J. Memb. Sci.  1993, 83,  211-220  $^{41 }$Kerres, J.; Cui, W.; Junginger, M.  J. Memb. Sci.  1998, 139, 227-241  $^{36 }$Zhao, D.; Liao, G.; Gao, G.; Liu,  F.  Macromolecules  2006, published on  Web Jan. 12, 2006, http://pubs.acs.org/cgi-bin/asap.cgi/mamobx/asap/pdf/  ma0524191.pdf  $^{42 }$Kerres. J.; Zhang, W.; Cui, W.  J Polym. Sci.: Part A: Polym. Chem.  1998,  36, 1441-1448  $^{43 }$Kerres, J.; Zhang, W. Tang,  C.  M. U.S. Pat. No. 6,767,585; granted at 27  Jul. 2004  nic acids according to the invention and if necessary  OH groups containing polymers.  [0047]  Cross-linking by addition of AgNO$_{3 }$ to the mix› ture of I-hydroxy methylene-1,1-bisphosphonic acid  containing OH-groups and if necessary polymers con› taining OH-groups ander hydrothermal conditions and  reduction of AgNO$_{3 }$ to elemental silver nanoparticles  and liberation of HNO/ 3  (FIG.  10  concerning the  cross-linking of OH-groups of different l-hydroxym› ethylene-1, 1-bisphosphonic acid molecules, if neces› sary by formation of never ending 3D networks by use  of molecules with several l-hydroxymethylene-1, 1- bisphosphonic acid groups);  [0048]  Cross-linking of l-hydroxymethylene-1,1-bis› phosphonic acids with OH groups containing polymers  by use of epichlorhydrine as cross-linker (FIG.  11)3 4 • 35 ;  [0049]  Cross-linking of OH groups of l-hydroxymeth› ylene-1,1-bisphosphonic acids and if necessary of OH  groups of the polymer with glutaraldehyde 36 ;  [0050]  Cross-linking of OH groups of l-hydroxymeth› ylene-1,1-bisphosphonic acids and if necessary of OH  groups of the polymer with melamine-formaldehyd  cross-linker 37 ;  [0051]  Cross-linking of OH groups of l-hydroxymeth› ylene-1,1-bisphosphonic acids and if necessary of OH  groups of the polymers after reaction of the OH groups  with Zcinnamon acid chloride by photocross-linking  (cycloaddition) under UV light3 8 ;  [0052]  Cross-linking of OH groups of l-hydroxymeth› ylene-1,1-bisphosphonic acids and if necessary of OH  groups of the polymer with polyvalent cations, e.g.  ca2+ 39;  [0053]  In principal all types of cross-linking reactions  which rely on cross-linking reactions of OH groups are  applicable to the l-hydroxymethylene-1, 1-bisphospho- $^{33 }$Luo, L.-B.; Yu, S.-H.; Qian, H.-S.; Zhou, T.  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