Janus polymerization consists of anionic and cationic ring opening polymerizations(AROP and CROP)at the two ends of a single propagating polymer chain,followed by a self-triggered chain extension generating multiblock...Janus polymerization consists of anionic and cationic ring opening polymerizations(AROP and CROP)at the two ends of a single propagating polymer chain,followed by a self-triggered chain extension generating multiblock copolymers(MBCPs)in one step.In the contribution,Janus polymerization by Tm(OTf)_(3) or Er(OTf)_(3) catalyst with an epoxy initiator is applied to synthesize MBCPs of semi-crystalline poly(ε-caprolactone)(PCL)blocks from coordinated AROP and poly(1,3-dioxolane-co-ε-caprolactone)(P(DO-co-CL))blocks from CROP of DO with CL.Meanwhile,amorphous random copolymers[P(DO-r-CL)]are synthesized as control by employing other rare earth triflates[RE(OTf)_(3),RE=Y,Nd,Gd and Lu]as catalysts or in the absence of an initiator via CROP.On account of the distinguishable chemical structures and thermal properties between Janus MBCPs and cationic random copolymers,Janus features are confirmed including the CROP and AROP at a single propagating chain.The resultant amphiphilic copolymers self-assemble to nanoparticles in aqueous solution with designable diameters with the corresponding ratios of hydrophilic and hydrophobic seg-ments.MBCPs exhibit good shape memory properties with appropriate deformation temperature close to human body's,providing a prospect on the applications in biomedical devices.展开更多
Multi-bond network（MBN） which contains a single network with hierarchical cross-links is a suggested way to fabricate robust hydrogels. In order to reveal the roles of different cross-links with hierarchical bond en...Multi-bond network（MBN） which contains a single network with hierarchical cross-links is a suggested way to fabricate robust hydrogels. In order to reveal the roles of different cross-links with hierarchical bond energy in the MBN, here we fabricate poly（acrylic acid） physical hydrogels with dual bond network composed of ionic cross-links between carboxylFe3＋ interactions and hydrogen bonds, and compare these dually cross-linked hydrogels with singly and ternarily cross-linked hydrogels. Simple models are employed to predict the tensile property, and the results confirm that the multi-bond network with hierarchical distribution in the bond energy of cross-links endows hydrogel with effective energy-dissipating mechanism. Moreover, the dually cross-linked MBN gels exhibit excellent mechanical properties（tensile strength up to 500 k Pa, elongation at break ~ 2400%） and complete self-healing after being kept at 50 °C for 48 h. The factors on promoting self-healing are deeply explored and the dynamic multi-bonds are regarded to trigger the self-healing along with the mutual diffusion of long polymer chains and ferric ions.展开更多
Through a controllable“reactivate””graft”synthetic route,two asymmetrical“Janus”dendronized polymers(DPs)were successfully synthesized.Dendrons were grafted to a linear polymer motherboard by a story-by-story co...Through a controllable“reactivate””graft”synthetic route,two asymmetrical“Janus”dendronized polymers(DPs)were successfully synthesized.Dendrons were grafted to a linear polymer motherboard by a story-by-story constructionmethod.Due to the heterogenetic“Janus”structure,with orderly arranged chromophore moieties,the polymers demonstrated extremely large second-order nonlinear optical(NLO)coefficients and excellent NLO thermal stability.DP-4l and DP-6l had high d33 values of 232 and 227 pm/V,respectively,which reached the highest value reported so far for linear-based polymers containing simple azo-chromophore moieties.The controllable synthesis sheds light on the structure–property relationships of NLO polymers and other dendronized-structure functional polymers.展开更多
基金supported by the National Natural Science Foundationof China(No.21871232)。
文摘Janus polymerization consists of anionic and cationic ring opening polymerizations(AROP and CROP)at the two ends of a single propagating polymer chain,followed by a self-triggered chain extension generating multiblock copolymers(MBCPs)in one step.In the contribution,Janus polymerization by Tm(OTf)_(3) or Er(OTf)_(3) catalyst with an epoxy initiator is applied to synthesize MBCPs of semi-crystalline poly(ε-caprolactone)(PCL)blocks from coordinated AROP and poly(1,3-dioxolane-co-ε-caprolactone)(P(DO-co-CL))blocks from CROP of DO with CL.Meanwhile,amorphous random copolymers[P(DO-r-CL)]are synthesized as control by employing other rare earth triflates[RE(OTf)_(3),RE=Y,Nd,Gd and Lu]as catalysts or in the absence of an initiator via CROP.On account of the distinguishable chemical structures and thermal properties between Janus MBCPs and cationic random copolymers,Janus features are confirmed including the CROP and AROP at a single propagating chain.The resultant amphiphilic copolymers self-assemble to nanoparticles in aqueous solution with designable diameters with the corresponding ratios of hydrophilic and hydrophobic seg-ments.MBCPs exhibit good shape memory properties with appropriate deformation temperature close to human body's,providing a prospect on the applications in biomedical devices.
基金financially supported by the National Natural Science Foundation of China(Nos.51633003 and 21474058)State Key Laboratory for Modification of Chemical Fibers and Polymer Materials,Donghua University(No.LK1404)+1 种基金Tsinghua University Scientific Research Project(No.2014Z22069)State Key Laboratory of Organic-Inorganic Composites,Beijing University of Chemical Technology(No.OIC-201601006)
文摘Multi-bond network（MBN） which contains a single network with hierarchical cross-links is a suggested way to fabricate robust hydrogels. In order to reveal the roles of different cross-links with hierarchical bond energy in the MBN, here we fabricate poly（acrylic acid） physical hydrogels with dual bond network composed of ionic cross-links between carboxylFe3＋ interactions and hydrogen bonds, and compare these dually cross-linked hydrogels with singly and ternarily cross-linked hydrogels. Simple models are employed to predict the tensile property, and the results confirm that the multi-bond network with hierarchical distribution in the bond energy of cross-links endows hydrogel with effective energy-dissipating mechanism. Moreover, the dually cross-linked MBN gels exhibit excellent mechanical properties（tensile strength up to 500 k Pa, elongation at break ~ 2400%） and complete self-healing after being kept at 50 °C for 48 h. The factors on promoting self-healing are deeply explored and the dynamic multi-bonds are regarded to trigger the self-healing along with the mutual diffusion of long polymer chains and ferric ions.
基金This research was made possible as a result of a generous grant from NSFC Foundation(Grant Number 21734007).
文摘Through a controllable“reactivate””graft”synthetic route,two asymmetrical“Janus”dendronized polymers(DPs)were successfully synthesized.Dendrons were grafted to a linear polymer motherboard by a story-by-story constructionmethod.Due to the heterogenetic“Janus”structure,with orderly arranged chromophore moieties,the polymers demonstrated extremely large second-order nonlinear optical(NLO)coefficients and excellent NLO thermal stability.DP-4l and DP-6l had high d33 values of 232 and 227 pm/V,respectively,which reached the highest value reported so far for linear-based polymers containing simple azo-chromophore moieties.The controllable synthesis sheds light on the structure–property relationships of NLO polymers and other dendronized-structure functional polymers.
