Synthesis and Characterization of Fluorescent and Thermo-responsive Polybutadiene Rubber

Polybutadiene rubber with the fluorescence and thermo-responsive properties was synthesized by macromolecular design. Firstly, the block copolymer polybutadiene-b-poly(-caprolactone)(HTBCP) was synthesized via the ring-opening polymerization of -caprolactone in presence of a hydroxyl-terminated polybutadiene(HTBP), which was catalyzed by stannous octanoate[Sn(Oct)2]. With the help of -caprolactone, polybutadiene rubber was improved in molecular weight and heat resistance, which was also terminated by hydroxyl (-OH). Then the macro-monomer of carboxyl- terminated poly(N-isopropyl acrylamide)(PNIPAm-COOH) was synthesized via the free radical polymerization in presence of mercaptoacetic acid(MAA). Finally the copolymer of polybutadiene rubber(HTBCP-b-PNIPAm) with moderate molecular weights (M_n=8000~15000) was synthesized from polybutadiene-b-poly(-caprolactone) and the macro-monomer of carboxyl- terminated poly(N-isopropyl acrylamide) by the condensation reaction, which was catalyzed by dichloroacety chloride(DCC). The polymer of polybutadiene-b-poly(-caprolactone)(HTBCP), poly(N-isopropyl acrylamide) (PNIPAm-COOH) and polybutadiene rubber (HTBCP-b-PNIPAm) were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), X-ray photoelectron spectroscopy (XPS), UV-Visible spectroscopy (UV-Vis), fluorescence spectroscopy etc. The results suggested that the copolymer of polybutadiene rubber was fluorescent having UV absorption at 274 nm and fluorescence excitation at 304 nm; besides the copolymer of polybutadiene rubber showed a critical phase transition temperature (LCST) at 30°C, at temperatures higher than 30°C, the copolymer HTBCP-b-PNIPAm has hydrophobic/hydrophobic chain segments, on the other hand it has hydrophobic/hydrophilic chain segments. The polybutadiene rubber with the fluorescence and thermo-responsive properties will make contribution in the field of luminescent or separating material.