Abstract:
The present invention relates to a preparation of modified organic core materials and metallic shell composite microspheres, in which, the surface zeta potential of an organic core materials can attract the opposite zeta potential of the polyelectrolyte and form a polyelectrolyte layer so as to modify the surface of organic core materials. Moreover, the polyelectrolyte layer could attract a first metal ions, particles or complexes added later in suitable condition such that the surface of organic core materials could be metallized and covered with a first metal layer. Furthermore, the organic core materials could be covered with at least one surface metal layer. The first metal layer can be modified by second metal layer with redox-transmetalation® technology to obtain multi-metal layers organic-metallic composite structure.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an electroless plating method, and more particularly, to a preparation of modified organic core materials and metallic shell composite microspheres. 
         [0003]    2. Description of the Prior Art 
         [0004]    Conventional methods of electroless plating in general perform the following procedure: 
         [0005]    Step 1: Roughening: using chromic acid to wash the surface of polymeric materials; 
         [0006]    Step 2: Sensitizing: adding stannous chloride or copper chloride to sensitize the surface of polymeric materials; 
         [0007]    Step 3: after covering the surface of polymeric materials with Sn, Cu, etc. ions, adding the precursor solution of noble metal (e.g., palladium chloride); and 
         [0008]    Step 4: depositing the metal Ni, Ag, Au, Co, Cu, etc. by electroless plating. 
         [0009]    Moreover, another conventional method for electroless plating can be performed the following procedure: 
         [0010]    Step 1: Polystyrene microspheres adsorb an ion absorbent; 
         [0011]    Step 2: adding the aforesaid polystyrene microspheres into palladium sulfate solution to let the surface of polymeric microspheres cover with palladium ions; 
         [0012]    Step 3: reducing the palladium ions to palladium particles to form a palladium layer on the polystyrene microspheres; 
         [0013]    Step 4: adding the polystyrene microspheres into the sodium succinate solution to form a slurry; and 
         [0014]    Step 5: adding the nickel sulfate solution with a specific Na/Ni concentration, pH and temperature drop by drop into the slurry, so as to form a Ni layer with 100 nm thickness on the polystyrene microspheres. 
         [0015]    Therefore, the main disadvantage of the conventional methods of electroless plating is the heavy and complicated procedure. In order to form a metal layer on the surface of polymeric microspheres, it need to be roughened, sensitized activated and adsorbed palladium on the surface of microspheres. What if any procedure couldn&#39;t properly execute, the quality of the final products won&#39;t be satisfying the requirement. 
         [0016]    Accordingly, in view of the conventional methods of electroless plating still having shortcomings and drawbacks, the inventor of the present application has made great efforts to make inventive research thereon and eventually provided a preparation of modified organic core materials and metallic shell composite microspheres. 
       SUMMARY OF THE INVENTION 
       [0017]    The primary objective of the present invention is to provide a preparation of modified organic core materials and metallic shell composite microspheres, in which, the surface zeta potential of an organic substrate can attract the opposite zeta potential of the polyelectrolyte and form a polyelectrolyte layer so as to modify the surface of organic core materials. Moreover, the polyelectrolyte layer could attract a first metal ions, particles or complexes added later in suitable condition such that the surface of organic core materials could be metallized and covered with a first metal layer. Furthermore, the organic core materials could be covered with at least one surface metal layer. The first metal layer can be modified by second metal layer with redox-transmetalation® technology to obtain multi-metal layers organic-metallic composite structure. 
         [0018]    Accordingly, to achieve the primary objective of the present invention, the inventor of the present invention provides a preparation of modified organic core materials and metallic shell composite microspheres, comprising a plurality of steps of: 
         [0019]    (1) adding an organic substrate  1  into a solvent to obtain a slurry; 
         [0020]    (2) adding a first polyelectrolyte  2  into the slurry, wherein the zeta potential of the first polyelectrolyte  2  is opposite to the surface zeta potential of the organic substrate  1 ; 
         [0021]    (3) adding a second polyelectrolyte  3  into the slurry, wherein the zeta potential of the second polyelectrolyte  3  is opposite to the zeta potential of the first polyelectrolyte  2 ; 
         [0022]    (4) adding a first metal compound  4  into the slurry; and 
         [0023]    (5) adding a reductant  5  into the slurry for making the first metal compound  4  be metalized, so as to form a first metal layer  6  on the surface of the organic substrate  1 . 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The invention as well as a preferred mode of uses and advantages thereof will be best understood by referring to the following detailed description of an illustrative embodiment in conjunction with the accompanying drawings, wherein: 
           [0025]      FIG. 1  is a flow chart of the preparation of modified organic core materials and metallic shell composite microspheres according to the present invention; 
           [0026]      FIG. 2  is a manufacturing process flow of the preparation of modified organic core materials and metallic shell composite microspheres according to the present invention; 
           [0027]      FIG. 3  is an analytic plot of the surface zeta potential of the organic core microspheres in different pH circumstances; 
           [0028]      FIG. 4  is an analytic plot of the surface zeta potential of the organic core microspheres modified by the polyelectrolyte (PAH and PAA) with different concentrations; 
           [0029]      FIG. 5  is a cross-sectional interface structure diagram of the PMMA-Ni composite microspheres; 
           [0030]      FIG. 6  is an analytic plot of volume resistivity of the PMMA-Ni composite microspheres prepared by the reductant with different concentrations; 
           [0031]      FIG. 7  is a cross-sectional and micro-display interface structure diagram of the PMMA-Ni—Au composite microspheres in different pH circumstances; 
           [0032]      FIG. 8  is an XRD plot of the PMMA-Ni—Au composite microspheres; 
           [0033]      FIG. 9  is an analytic plot of volume resistivity of the PMMA-Ni—Au composite microspheres in different PH circumstance; and 
           [0034]      FIG. 10  is a schematic diagram of a magnetic effect experiment for the PMMA-Ni—Au composite microspheres. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0035]    To more clearly describe a preparation of modified organic core materials and metallic shell composite microspheres according to the present invention, embodiments of the present invention will be described in detail with reference to the attached drawings hereinafter. 
         [0036]    With reference to  FIG. 1 , which illustrate a flow chart of the preparation of modified organic core materials and metallic shell composite microspheres according to the present invention. Moreover, please simultaneously refer to  FIG. 2 , there is shown a manufacturing process flow of the preparation of modified organic core materials and metallic shell composite microspheres according to the present invention. As shown in  FIG. 1  and  FIG. 2 , the preparation of modified organic core materials and metallic shell composite microspheres mainly comprises  5  steps: 
         [0037]    Firstly, the method proceeds to steps (S 01 ) and (S 02 ) for adding an organic substrate  1  into a solvent to obtain a slurry and then adding a first polyelectrolyte  2  into the slurry; in which, particularly, the zeta potential of the first polyelectrolyte  2  is opposite to the surface zeta potential of the organic substrate  1 . After finishing the step (S 02 ), step (S 03 ) is next executed for adding a second polyelectrolyte  3  into the slurry, wherein the zeta potential of the second polyelectrolyte  3  is opposite to the zeta potential of the first polyelectrolyte  2 . Subsequently, the method executes step (S 04 ) for adding a first metal compound  4  into the slurry; and eventually, the method proceeds to step (S 05 ) for adding a reductant  5  into the slurry, so as to make the first metal compound  4  be metalized, and then a first metal layer  6  is formed on the surface of the organic substrate  1 . 
         [0038]    Thus, through above descriptions, the basic steps of the preparation of modified organic core materials and metallic shell composite microspheres have been introduced completely and clearly. Moreover, as shown in  FIG. 1  and  FIG. 2 , the preparation of modified organic core materials and metallic shell composite microspheres further comprises steps (S 06 ) and (S 07 ). In the step (S 06 ), a second metal compound  7  is added into the slurry, and then after an ion exchange spontaneously occurs between the second metal compound  7  and the first metal compound  4  of the first metal layer  6  through redox during the step (S 07 ), the first metal layer  6  is modified to a second metal layer  8 . 
         [0039]    Herein, it needs to further explain that, the organic substrate  1  in aforesaid surface metallization method is an organic material with polyester functional group, i.e., the organic substrate  1  is covered with at least one surface metal layer. 
         [0040]    Besides, the first polyelectrolyte  2  and the second polyelectrolyte  3  are selected from the group consisting of: Poly (allylamine hydrochloride) (PAH), Poly (diallyldimethylammonium chloride) (PDDA), Poly (acrylic acid) (PAA), and Poly (styrene sulfonate) (PSS). Moreover, the reductant  5  in aforesaid preparation of modified organic core materials and metallic shell composite microspheres is selected from the group consisting of: Dimethylamine borane (DMAB) and NaBH 4 . 
         [0041]    Thus, through the descriptions, the preparation of modified organic core materials and metallic shell composite microspheres of the present invention has been completely introduced and disclosed; next, a variety of experiment data will be presented for proving the practicability and performance of this preparation. 
       Experiment I 
       [0042]    A plurality of PMMA (Polymethylmethacrylate) microspheres having a diameter ranged from 200 nm to 8 μm are provided as organic core microspheres (the organic substrate), wherein the average diameter of the PMMA microspheres is 4 μm. Moreover, Poly (allylamine hydrochloride), i.e., the PAH, are used as a cationic polyelectrolyte; and oppositely, Poly (acrylic acid), i.e., the PAA, is used as an anionic polyelectrolyte. 
         [0043]    Please refer to  FIG. 3 , there is shown an analytic plot of surface zeta potential of the organic core microspheres in different pH circumstances. As shown in  FIG. 3 , PMMA-PAH curve is obtained by measuring the surface zeta potential of the organic core microspheres mixed with 0.2 g PMMA and 0.022 mM PAH polyelectrolyte; in addition, As-received PMMA curve is obtained by measuring the surface zeta potential of the organic core microspheres mixed with 0.2 g PMMA microspheres; moreover, PMMA-PAH-PAA curve is obtained by measuring the surface zeta potential of the organic core microspheres mixed with 0.2 g PMMA microspheres, 0.022 mM PAH and 0.022 mM PAA polyelectrolytes. Obviously, the experiment results of  FIG. 3  reveal that the polyelectrolytes of PAA and PAH can indeed make a modification effect to the surface zeta potential of the organic core microspheres under a wide pH range (pH4-pH10). 
         [0044]    Please refer to  FIG. 4 , there is shown an analytic plot of the surface zeta potential of the organic core microspheres modified by the polyelectrolytes (PAH and PAA) with different concentrations. As  FIG. 4  shows, PMMA-PAH data points are obtained by measuring the surface zeta potential of the organic core microspheres PMMA modified by the PAH polyelectrolytes with the concentration of 0.01 mM-0.07 mM. The PMMA-PAH-PAA data points are obtained by measuring the surface zeta potential of the organic core microspheres PMMA modified by the PAH and PAA polyelectrolytes with the concentration of 0.01 mM-0.07 mM. From  FIG. 4 , it can find that a gentle region is observed when the concentration of the used polyelectrolytes exceeds 0.02 mM, and that means the modification effect made by the polyelectrolytes reaches to the upper limitation. 
         [0045]    Furthermore, an FIB-SEM (Focused Ion Beam Scanning Electron Microscopy) is used for observing the cross-sectional interface image of the microspheres of PMMA-Ni composite microspheres. Please refer to  FIG. 5 , which illustrates the cross-sectional interface structure diagram of the PMMA-Ni composite microspheres; wherein the PMMA-Ni composite microspheres are made by adding a precursor of 0.255M NiCl 2 , a reductant of 0.17M DMAB (Dimethylamine Borane) into the polyelectrolyte with a fixed concentration of 0.22 mM and then using aforesaid polyelectrolyte to execute a surface metallization to the organic core microspheres. As shown in  FIG. 5 , the interface between the organic material and the metal layer is continues and delicate; therefore, it can be noted that the polyelectrolyte displays a stable ability of adsorbing the organic material with metal compound which is selected from the group consisting of: metal ion, metal particles and metal complexes. 
         [0046]    After finishing the surface metallization of the organic core microspheres, the organic core microspheres are subsequently pressed into tablets by hot pressing method (press 30s with 110 MPa at 130° C.) and then the volume resistivity of the organic tablets are measured by four point probe resistivity measurements. Please refer to  FIG. 6 , which illustrates an analytic plot of volume resistivity of the PMMA-Ni composite microspheres prepared by the reductant with different concentrations. As shown in  FIG. 6 , the experiment results indicate that the organic core microspheres (tablets) perform the lowest volume resistivity when the concentration of the reductant (DMAB) is 0.17M. 
       Experiment II 
       [0047]    Furthermore, according to following Eq. (1), it is able to know that an ion exchange would occur spontaneously through redox-transmetalation. The redox-transmetalation can oxidize the Ni layer on the surface of an organic material and make Au (III) reduce to Au (0), so as to form a continuous Au layer covering the Ni layer on the surface of the organic core microspheres. 
         [0000]      3Ni (s) +2AuCl 4   − =3Ni 2+ +2Au (s) +8Cl (aq)   −   Eq. (1)
 
         [0048]    Please refer to  FIG. 7 , which illustrates a cross-sectional and micro-display interface structure diagram of the organic core microspheres of 
         [0049]    PMMA-Ni—Au compound in different pH circumstances.  FIG. 7  ( a ) is the micro-display diagram of PMMA-Ni composite microspheres microspheres, and  FIGS. 7  ( b ), ( c ), ( d ) and ( e ) are the micro-display diagram of PMMA-Ni—Au composite microspheres in pH 6, 7, 8, and 9, respectively. By inspecting the cross-sectional interface structure of the PMMA-Ni—Au composite microspheres through FIB-SEM, it can be found that more delicate cross-sectional interface structure of PMMA-Ni—Au composite microspheres is obtained in pH 7, 8 and 9. Please continuously refer to  FIG. 8 , which illustrates an XRD plot of the PMMA-Ni—Au composite microspheres. Through  FIG. 8 , it can be found that the Au layer is formed and covers over the Ni layer on the surface of organic microsphere after redox-transmetalation. 
         [0050]    Please continuously refer to  FIG. 9 , there is shown an analytic plot of the volume resistivity of the PMMA-Ni—Au composite microspheres in different pH circumstances. Similarly, after the surface metallization of the organic core microspheres is carried out, the PMMA-Ni—Au composite microspheres are subsequently pressed into tablets by hot pressing method (press 30s with 110 MPa at 130° C.), and then the volume resistivity of the PMMA-Ni—Au composite tablets are measured by using four point probe resistivity measurements. As  FIG. 9  shows, the experiment results reveal that the PMMA-Ni—Au composite microspheres (tablets) perform the lowest volume resistivity when the pH is ranged from 7 to 8. 
         [0051]    Besides, for determining the surface metallization of the PMMA-Ni—Au composite microspheres, a magnetic effect experiment is executed. Please refer to  FIG. 10 , which illustrates a schematic diagram of a magnetic effect experiment for the PMMA-Ni—Au composite microspheres. As shown in  FIG. 10 , the solution is apparently clear after adding a magnetic field. Through experiment result, it can find that the Ni layer of the PMMA-Ni—Au composite microspheres isn&#39;t consumed entirely by Au ion in redox-transmetalation. 
         [0052]    The above description is made on embodiments of the present invention. However, the embodiments are not intended to limit scope of the present invention, and all equivalent implementations or alterations within the spirit of the present invention still fall within the scope of the present invention.