For example, PBz cured from dicarboxylic acid is used as a coating material for circuit boards and semiconductors.
Thus, focusing on reducing the polymerization temperature and increasing the crosslink density (CLD) (by tightening the PBz network structure) are expected to enhance their thermo-mechanical performance .
The concept of preparing main-chain PBz (MCPBz) precursors has been developed recently [18, 19].
The precipitate thus obtained was washed with distilled [H.sub.2]O several times, filtered, and finally dried in a vacuum at 50[degrees]C for 12 h to afford the PBz precursor (Scheme 1).
Similarly, the other two PBz precursors were synthesized by using the diamines [1,4-diaminobutane (1.76 g, 0.02 m) and tetraethylenepentamine (3.8 mL, 0.02 m)] instead of ethylene diamine.
Approximately, 1 g of the PBz precursors--(PBz-eda, PBzdba and PBz-tepa) was taken in a separate glass plate.
For the VB-a monomer system that had been heated at various curing temperatures (Figure 1(a)), the WCA increased upon increasing the curing temperature, from 82[degrees] at 80[degrees]C to 103[degrees] at 200[degrees]C, similar to the behavior of a previously reported BA-a PBZ system .
Figure 2 displays the effects on the UV-exposed PBZ films after thermal treatment at various temperatures.
Figures 4 and 5 present XPS analyses of the compositions of a PBZ film after alternating UV illumination and thermal treatment.
The physical interactions among the PBZ polymer chains, mainly through intramolecular hydrogen bonding of the OH groups with the nitrogen atoms, as depicted in Scheme 1, have a critical effect on the properties of these materials .
The ability to control the WCA of this PBZ surface through irradiation with UV light suggested the intriguing possibility of using this system to prepare materials with properties varying from superhydrophobicity and superhydrophilicity.
This superhydrophobic PBZ surface had a rough surface possessing both micro- and nanoscale binary structures.