Various π-conjugated copolymers constituted of π-excessive thiophene, selenophene, or furan units (Ar) and π-deficient pyridine or quinoxaline (Ar‘) units have been prepared in high yields by the following organometallic polycondensation methods:  (i) n X−Ar−Ar‘−X + n Ni(0)Lm → (-Ar−Ar‘)- n (X = halogen, Ni(0)Lm = zerovalent nickel complex), (ii) n X−Ar−X + n Me3Sn−Ar‘−SnMe3 → (-Ar−Ar‘)- n (palladium catalyzed), and (iii) a X−Ar−X + b X−Ar‘−X + (a + b)Ni(0)Lm → (-Ar) x (Ar‘)- y . Powder X-ray diffraction analysis confirms an alternative structure of a polymer prepared by the method ii. The copolymers have a molecular weight of 5.4 × 103 to 3.3 × 105 and an [η] value of 0.37 to 4.4 dL g-1. π−π* absorption bands of the copolymers generally show red shifts from those of the corresponding homopolymers, (-Ar)- n and (-Ar‘)- n , and the red shifts are accounted for by charge-transferred CT structures of the copolymers. For example, an alternative copolymer of thiophene and 2,3-diphenylquinoxaline gives rise to an absorption band at λmax = 603 nm, whereas homopolymers of thiophene and 2,3-diphenylquinoxaline exhibit absorption peaks at about 460 and 440 nm, respectively. The CT copolymers are electrochemically active in both oxidation and reduction regions, showing oxidation (or p-doping) peaks in a range of 0.39 to 1.32 V vs Ag/Ag+ and reduction (or n-doping) peaks in a range of −1.80 to −2.22 V vs Ag/Ag+, respectively. Copolymers of pyridine give unique cyclic voltammograms exhibiting p-undoping peaks at potentials much different (about 2−3 V lower) from the corresponding p-doping potentials, and this large difference between p-doping and p-undoping potentials is explained by an EC mechanism. They are converted into semiconductors by chemical and electrochemical oxidation and reduction. Copolymers of thiophene with pyridine and quinoxaline show the third-order nonlinear optical susceptibility χ(3) of about 5 × 10-11 esu at the three-photon resonant wavelength, which is 5−7 times larger than those of the corresponding homopolymers and related to the CT structure in the copolymers.

Thermoresponsive block copolymer brush with cell affinity peptides was prepared via two steps of ATRP and subsequent click reaction. The prepared polymer brush can purify cells with high selectivity by simply changing temperature.