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Smart polymeric materials have received extensive attention for various applications. Here, we reported a facile and efficient approach to prepare a class of pegylated polypeptoids by a combination of ring-opening polymerization (ROP) and post-modification strategy. Three different initiators were involved to mediate the polymerization of the monomers. Unlike the previously reported pegylated polypeptoids, the obtained polypeptoids show completely reversible thermoresponsive behaviors in aqueous solution after 8 heating and cooling cycles. In addition, the phase transition of the polypeptoid solutions can be very sharp (ΔT < 5 °C), which is comparable to poly( N -isopropylacrylamide) (PNIPAM). The influence of temperature on solution properties of the polypeptoids has been systematically studied. The clouding points (CPs) of the polypeptoids are highly tunable depending on the degree of polymerization (DP), the side-chain length, and the polymer concentration. We demonstrate that the thermoresponsive property of the polypeptoid may possibly arise from the incorporation of thioether groups and the branched molecular architecure of side chains. These features enable the pegylated polypeptoids potential candidates for next generation of smart polymeric materials. [ABSTRACT FROM AUTHOR]

Tough and transparent poly(L-lactic acid)/poly(D-lactide)-b-poly(butadiene)-b-poly(D-lactide) (PLLA/PDLA-PB-PDLA) film with balanced strength was obtained. The PDLA-PB-PDLA triblock copolymer was firstly synthesized by ring-opening polymerization (ROP) of D-lactide using bihydroyl-terminated polybutadiene as macroinitiator, and then the obtained triblock copolymer was mixed with PLLA in solution. The blended films kept in good transparence even when the loading of PDLA-PB-PDLA reached to 15 wt%. Meanwhile, the elongation at break of the PLLA/PDLA-PB-PDLA film increased by ∼10 times without a significant reduction in tensile strength as compared with that of pure PLLA. The mechanical property was ascribed to the synergetic effect of the flexible PB chains and the stereocomplex crystals formed between PLLA matrix and PDLA chains. "Salami-like" dispersed-phase with nanometer scales was observed, which would contribute to the transparency of the blended film. The tensile fractured morphologies indicated that shear yield of the matrix and cavitation might be the major toughening mechanism of PLLA/PDLA-PB-PDLA film. We prepared tough and transparent poly(L-lactic acid) film with balanced tensile strength by blending with poly(D-lactide)-b-poly(butadiene)-b-poly(D-lactide) triblock copolymer. [Display omitted] • Tough and transparent poly(L-lactic acid)/poly(D-lactide)-b-poly(butadiene)-b-poly(D-lactide) film with balanced strength. • The mechanical properties were ascribed to the synergetic effect of the flexible PB chains and the stereocomplex crystals. • "Salami-like" dispersed-phase with nanometer scales would contribute to the transparency of the blended film. • Shear yield of the matrix and cavitation might be the major toughening mechanism of PLLA/PDLA-PB-PDLA film. [ABSTRACT FROM AUTHOR]

Smart protein-mimetic materials have received increasing interest for many applications. Here, we reported a facile and efficient approach to prepare a class of dual-responsive copoly( l -glutamate)s by ring-opening polymerization (ROP) and post-modification strategy. Both the oligo(ethylene glycol) (OEG) and glutamic acid residues were incorporated to offer thermal- and pH-responsive property simultaneously. We present a systematic study of the influence of both temperature and pH on the solution properties of the copolypeptides. The copolypeptides show entirely reversible pH-dependent thermal-responsive behaviors with tunable phase transition temperatures. It is demonstrated that the sequence of the polymer units can also influence the solution behavior. The α-helix conformation appears to be the dominant secondary conformation, which shows the pH dependence, but generally irrespective of the temperature. We further verify that the reduced circular dichroism (CD) signal upon heating above the clouding point (CP) is entirely due to the aggregation of the polymer chains. All these features make the obtained polypeptides potential candidates for next generation of smart protein-mimetic materials. [ABSTRACT FROM AUTHOR]

A new polystyrene supported cyclic trimeric phosphazene base (PS-CTPB) was designed and synthesized. It was demonstrated that hypotoxic poly (ε -caprolactone) (PCL) can be directly prepared via ring-opening polymerization (ROP) by using PS-CTPB as catalyst. The PS-CTPB catalyst was prepared via immobilization of cyclic trimeric phosphazene base (CTPB) moiety on polystyrene microspheres to obtain a heterogeneous organocatalyst. The composition and chemical structure of the heterogeneous PS-CTPB was systematically characterized using solid-state 13C and 31P MAS NMR, FTIR, SEM and element analysis. It was found that immobilization of CTPB on PS microsphere maintained its excellent catalytic activity for ROP of ε -CL, δ -valerolactone (δ -VL), rac -lactide (rac -LA). Moreover, the heterogeneous PS-CTPB could be easily separated or recycled via simple filtration. Given that, the obtained polyesters contained negligible catalyst residual, so the obtained PCL samples have low cytotoxicity indicated from MTT assay. It was worth noting that the recycled PS-CTPB catalyst could be reused for another six consecutive cycles without significant decrease of catalytic activity. Image 1 • PS-CTPB is prepared via immobilization of cyclic trimeric phosphazene base moiety on polystyrene microspheres. • PS-CTPB exhibits highly efficient for ring-opening polymerization of cyclic esters. • PS-CTPB is easily recovered and reusable for six consecutive cycles without obvious deactivation. • The PCLs without catalyst-residue have been facilely synthesized using PS-CTPB by simple filtration. • MTT assay indicates that the resulting PCLs have low cytotoxicity. [ABSTRACT FROM AUTHOR]