Shengwen Zhang

Preparation and characterization of carboxylterminated poly (butadiene-co-acrylonitrile) -epoxy resin prepolymers for fusion-bonded-epoxy powder coating

Liquid carboxyl-terminated poly(butadiene-co-acrylonitrile)(CTBN)-epoxy resin(EP) prepolymers were prepared with different contents of CTBN. The chemical reactions between EP and CTBN were characterized by Fourier ransform infrared (FTIR) spectroscopy and gel permeation chromatography (GPC). The scanning electron micrograph (SEM) and dynamic mechanical analysis (DMA) of curing films showed phase separation, and the rubber particles were finely dispersed in the epoxy matrix. Mechanical properties analysis of curing films showed that impact strength and elongation at break increased significantly upon the addition of CTBN, indicating good toughness of the modified epoxy resins. Thermogravimetric analysis (TGA) showed that the incorporation of CTBN had little effect on the thermal stability of EP. Fusion-bondedepoxy (FBE) powder coatings modified with CTBN-EP prepolymers were prepared. The experimental results demonstrate the ability of CTBN-EP prepolymers, toughening technology to dramatically enhance the flexibility and impact resistance of FBE coatings without compromising other key properties such as corrosion protection.

Synthesis and properties of UV-curable hyperbranched polyurethane and its application in the negative-type photoresist

UV-curable hyperbranched polyurethane (UV-HBPU) containing carboxyl groups was synthesized from isophorone diisocyanate (IPDI), diethanolamine (DEOA), polyethylene glycol (PEG-400), hydroxyethyl acrylate (HEA), and 2,2-bis (hydroxymethyl) propionic acid (DMPA). The UV-HBPU was used as a negative-type photoresist for a printed circuit board (PCB). Fourier-transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1HNMR) spectroscopy of UV-HBPUs indicated that the synthesis was successful. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed that the thermal stability of the UV-HBPUs decreased as the HEA content increased. The polymer exhibited excellent photoresist properties, and the resolution of circuits based on this negative-type photoresist reached 10 μm.

Photosensitive acrylate copolymer for electrodeposition photoresist

A photosensitive random copolymer UPDHES was prepared by introducing the acrylate groups into the side chain of the copolymer composed of N,N-dimethylaminomethyl methacrylate (DMAEMA), 2-hydroxyethyl acrylate (HEA), 2-ethylhexyl acrylate (EHA), and styrene (St) (PDHES). The molecular structure of UPDHES was characterized by FTIR and 1H NMR analyses. Self-assembling of the random copolymer UPDHES in water formed positively charged photosensitive particles, and the particles were measured by TEM to be spherical-like nano-particles range from 20–90 nm. The oriented deposition of the particles on gold electrode was investigated with the cyclic voltammetry and TEM under low applied voltage. The influence of high applied voltage on current density in electrodeposition process and thickness of films were investigated also. Besides, the photopolymerization rate and final C=C conversion reached to the highest values with 3 wt % Irgacure 1173 addition, whereas decreased as further added. Moreover, an exposure-development procedure of electrodeposition UPDHES film produced developed diagram with resolution of 15 μm.