Poly(lactic-co-glycolic acid) (PLGA) were grafted to both ends of Pluronic ® F68 ((EO) 75 (PO) 30 (EO) 75 ) triblock copolymer to produce poly{(lactic acid) m -co-(glycolic acid) n }-b-poly(ethylene oxide) 75 -b-poly(propylene oxide) 30 -b-poly(ethylene oxide) 75 -b-poly{(lactic acid) m -co-(glycolic acid) n } (PLGA-F68-PLGA) pentablock copolymers. Molecular weights of PLGA blocks were controlled and five kinds of pentablock copolymers with different PLGA block lengths were synthesized using in-situ ring-opening polymerization of D,L-lactide and glycolide with tin(II) 2-ethylhexanoate (Sn(Oct) 2 ) catalyst. PLGA-F68-PLGA pentablock copolymers were characterized by ¹H-and ¹³C-NMR, GPC, and TGA. The numbers (2m, 2n) of repeating units for lactic acid and glycolic acid inside PLGA segments were obtained as (48, 17), (90, 23), (125, 40), (180, 59), and (246, 64), with 1 H-NMR measurement. From NMR data, the resultant molecular weights were determined in the range of 12,700-29,700, which were similar to those obtained from GPC. Polydispersity index was increased in the range of 1.32-1.91 as the content of PLGA blocks increased. TG and DTG thermograms showed discrete degradation traces for PLGA and F68 blocks, which indicate the weight fractions of PLGA blocks in pentablock copolymers can be calculated by TG profile and it is possible to remove PLGA block selectively. Hydrodynamic radius and radius of gyration of pentablock copolymer micelle were obtained in the range of 46-68 nm and 31-49 nm, respectively, in very dilute (i.e. 0.005 wt %) aqueous solution of THF:H 2 O = 10:90 by volume at 25 o C.

We investigated the effects of bath composition on the adhesion characteristics of electroless Cu on epoxy-based polymer substrates. The Cu layer was electroless-plated on the epoxy-based polymer substrate via four electroless-plating baths. A Cu layer was electroplated, which was then cured at 150°C for 1 h. The adhesion was evaluated using a 90° peel test. The size of the nodules and grains found in the electroless Cu layers decreased with increasing electrolyte concentration in the plating bath, resulting in increased hardness. At the highest electrolyte concentration, the electroless Cu layer exhibited high porosity in conjunction with the least coverage. The porosity of the electroless Cu layer decreased and the coverage improved with decreasing electrolyte concentration; however, a non-uniform layer formed at the lowest electrolyte concentration. The peel strength increased initially with the bath concentration, and then decreased upon further increase in bath concentration. The variation of the peel strength was related to the coverage and the hardness of the electroless Cu layer. We utilized a two-step electroless-plating method (the first layer with better coverage and second layer with larger ductility). The peel strength of the optimized double-layered electroless Cu layer was higher than that of the single-layered electroless Cu layer.

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