The graft copolymer of poly-(N-epsilon-carbobenzyloxy-L- lysine)-g-poly(tetrahydrofuran) (PZLL-g-PTHF) could be successfully synthesized via the nucleophilic substitution reaction of PTHF+ living polymer chains with secondary amine side groups in the PZLL backbone. The amphiphilic graft copolymers of polylysine-g-poly(tetrahydrofuran) (PLL-g-PTHF) could be obtained by complete deprotection of the precursor of PZLL-g-PTHF. The obvious microphase separation was observed in both PLL-g-PTHF and PZLL-g-PTHF because of the incompatibility between the two kinds of segments. Their micro morphology is dependent on the chemical structure of backbones and the grafting number (GN) of branches. PZLL-g-PTHF is a hydrophobic graft copolymer and the water contact angles (WCAs) of copolymer surfaces decreased from 103 to 91 & DEG; with the increase of GN from 5 to 21. Interestingly, PLL-g-PTHF is an amphiphilic graft copolymer and their WCAs increased from 52 to 90 & DEG; with the increase of GN from 5 to 21. Both PZLL-g-PTHF and PLL-g-PTHF copolymers show good biocompatibility and anti-protein adsorption. The resulting PZLL-g-PTHF copolymers carrying a small amount of Ag nanoparticles, in situ generated from coinitiator AgClO4 for the synthesis of PTHF+ living chains, exhibit high killing efficiency (> 95%) for both Escherichia coli and Staphylococcus aureus. PLL-g-PTHF/Ag nanocomposites show extremely high killing efficiency (> 99%) against both S. aureus and E. coli for binary contribution from Ag nanoparticles and PLL. The antifouling and antibacterial graft copolymers would potentially have biological and medical applications.

The acylated propylene glycol alginate-g-polytetrahydrofuran amphiphilic graft copolymers (APGA-g-PTHF) with various grafting numbers (G(N)) of 3-23 per 1000 monosaccharide rings and PTHF (PTMG or PTMO) branches with different molecular weights (M-n,M-PTHF) of 600-3400 g/mol could be successfully synthesized via nucleophilic substitution of PTHF living chains carrying oxonium ions with the -OH side groups of APGA backbone. The nanophase separation, the hydrophobicity and the surface roughness were increased due to the less restricted movement of hydrophobic PTHF branches to the surface. APGA-g-PTHF graft copolymers behave low cytotoxicity and good anti-protein performance. Interestingly, APGA-g-PTHF amphiphilic graft copolymers could form homogeneous nanospheres (< 250 nm) via self-assembly in H2O/CH2Cl2 medium which could be used for drug (ibuprofen or curcumin) carriers having high drug loading efficiency (similar to 45%) and fast release behavior. The nanospheres carried curcumin behave very higher (10-fold) anticancer effect against HeLa cells than that of curcumin and thus reduce the harmful drug dosage. Moreover, the nanospheres carried drug might enter into HeLa cells and present pH-sensitive drug release. To the best of our knowledge, this is the first example of PGA based graft copolymers for highly effective nano-carriers and anti-protein surfaces, which would have a prospect in biomedical areas.

Novel copolymer brushes of quaternized sodium alginate-g-(2-ethyl-2-oxazoline)n are achieved by the grafting reaction of 2-ethyl-2-oxazoline (EOX) from benzyl bromide groups in quaternized sodium alginate (QSA). The average number of (EOX)n structural units is mediated from 1 to 5 by changing the molar ratio of the EOX monomer to benzyl bromide side groups. There exists obvious microphase separation between the QSA backbone and (EOX)n segments in the copolymer brushes due to their thermodynamic incompatibility. The strong hydrogen-bonding interaction between -OH groups in the backbone and N─C═O groups in (EOX)n segments is helpful for the construction of reversible supramolecular networks. The copolymer brushes show low cytotoxicity for HeLa cells and good antibacterial properties for Escherichia coli and Staphylococcus aureus for the contribution of hydrophilic (EOX)n segments and antibacterial activity of the quaternary ammonium. The antiprotein behavior of polymer surfaces is improved after rearrangement of (EOX)n segments by tetrahydrofuran (THF) vapor induction. These copolymer brushes have good prospects for biomedical applications.