Rare-earth ternary catalysts Y（CCl3COO）3-ZnR2-glycerin were prepared for the copolymerization of carbon dioxide and propylene oxide （PO）, where dialkylzincs （ZnR2） were diethylzinc, di（n-propyl）zinc, di（n-bu...Rare-earth ternary catalysts Y（CCl3COO）3-ZnR2-glycerin were prepared for the copolymerization of carbon dioxide and propylene oxide （PO）, where dialkylzincs （ZnR2） were diethylzinc, di（n-propyl）zinc, di（n-butyl）zinc, di（i-propyl）zinc, di（i-butyl）zinc, di（s-butyl）zinc,respectively. The Y（CCl3COO）3-ZnR2-glycerin catalysts displayed the highest catalytic activity at the molar ratio of Y（CCl3COO）3：ZnR2：glycerin = 1：20：10. In the same copolymerization condition, catalysts containing dialkylzincs with branched alkyl group showed lower catalytic activity than that with primary alkyl group. For those catalysts including dialkylzincs with primary alkyl group, their catalytic activity decreases with increasing number of carbon atom in the alkyl group with the following sequence： Y（CCl3COO）3-ZnEt2-glycerin 〉 Y（CCl3COO）3-Zn（n- Pr）2-glycerin〉Y（CCl3COO）3-Zn（n-Bu）2-glycerin. However, the alkyl group in the dialkylzinc does not influence the insertion of PO into the propagation chain end.展开更多
Poly(butylene adipate-co-terephthalate) (PBAT) is currently the largest commercial biodegradable plastics with good toughness and film forming properties, whereas, the inferior barrier and mechanical properties hinder...Poly(butylene adipate-co-terephthalate) (PBAT) is currently the largest commercial biodegradable plastics with good toughness and film forming properties, whereas, the inferior barrier and mechanical properties hinder its applications. Biodegradable poly(propylene carbonate) (PPC) with excellent barrier properties and high strength is a natural choice to address above issue. However, it is challenging to improve the compatibility of these two polymers. Herein, we prepared a reactive compatibilizer with double bond side group through terpolymerization of CO_(2)/propylene oxide/glycidyl methacrylate to enhance the properties of PBAT/PPC blends. Upon addition of 1 wt% compatibilizer, the PBAT/PPC blends (75/25, W/W) showed an increased water vapor barrier property changed from 424 g·m^(−2)·d^(−1) to 204 g·m^(−2)·d^(−1) compared to the control sample. Moreover, the tensile strength and elongation at break increased from 24.7 MPa to 30.3 MPa and from 858% to 1142%, respectively. The PBAT/PPC composite also displayed excellent biodegradability under composting conditions, as confirmed by the significantly decreased molecular weight. The present work provides an efficient way to barrier biodegradable film from PBAT of practical utilization.展开更多
Aliphatic polyamides have been considered as eco-friendly materials,useful for a wide range of applications.However,it still presents obstacle to produce sustainable aliphatic polyamides from abundant renewable source...Aliphatic polyamides have been considered as eco-friendly materials,useful for a wide range of applications.However,it still presents obstacle to produce sustainable aliphatic polyamides from abundant renewable sources.Herein,we describe that 4-hydroxyproline(4-HYP),a renewable resource,was readily converted to its corresponding bicyclic bridged lactam monomers bearing pendant Boc-protected secondary amino group,and oligo-ethylene glycol group.Lithium hexamethyldisilazide(LiHMDS)-mediated polymerization of the resulting monomers exhibited a controlled feature,affording sustainable aliphatic polyamides with number-average molecular weight up to 73 kg/mol and a low molecular weight distribution?<1.28.Overall,this work can lead to a novel kind of functional and sustainable polyamides with potential applications,including degradable plastics,and drug delivery.展开更多
Sustainable blends of poly(propylene carbonate)(PPC)and stereocomplex polylactide(sc-PLA)were prepared by melt blending equimolar poly(L-lactic acid)(PLLA)and poly(D-lactide acid)(PDLA)with PPC to form sc-PLA crystals...Sustainable blends of poly(propylene carbonate)(PPC)and stereocomplex polylactide(sc-PLA)were prepared by melt blending equimolar poly(L-lactic acid)(PLLA)and poly(D-lactide acid)(PDLA)with PPC to form sc-PLA crystals in situ in the melt blending process.Differential seanning calorimetry analysis revealed that only sc-PLA,no homo-crystallization of PLLA or PDLA,formed in the PPC matrix as the sc-PLA con tent was more than 10 wt%.Very in triguingly,scan ning electronic microscopy observati on showed that sc-PLA was evenly dispersed in the PPC phase as spherical particles and the sizes of sc-PLA particles did not obviously increase with in creasing sc-PLA con tent.As a con seque nee,the rheological properties of PPC were greatly improved by incorporation of sc-PLA.When the sc-PLA con tent was 20 wt%,a percolati on n etwork structure was formed,and the blends showed solid-like behavior.The sc-PLA particles could reinforce the PPC matrix,especially at a temperature above the glass transition temperature of PPC.Moreover,the Vicat softening temperature of PPC/sc-PLA blends could be increased compared with that of neat PPC.展开更多
Aluminum porphyrin complexes are heavy-metal-free and soil-tolerant green catalysts for the copolymerization of CO2 and propylene oxide（PO）, but they suffer from relatively poor poly（propylene carbonate）（PPC） se...Aluminum porphyrin complexes are heavy-metal-free and soil-tolerant green catalysts for the copolymerization of CO2 and propylene oxide（PO）, but they suffer from relatively poor poly（propylene carbonate）（PPC） selectivity. Herein, steric hindrance porphyrin ligand was used to enhance the PPC selectivity. Typically, a bulky anthracene-like group was incorporated into the porphyrin ring to form 5,10,15,20-tetra（1,2,3,4,5,6,7,8-octahydro-1,4：5,8-dimethanoanthracen-9-yl）porphyrin, the aluminum porphyrin complex with this ligand, in combination with bis（triphenylphosphine）iminium chloride as a co-catalyst, produced completely alternate PPC. Additionally, the obtained PPC showed high regioselectivity, with a head-to-tail linkage content（HT） of 92%. Therefore, we demonstrated that introduction of bulky steric ligand into the porphyrin ring could reduce the propylene oxide homopolymerization activity leading to excellent PPC selectivity, and improve regioselectivity for the PO ring-opening during the copolymerization.展开更多
A series of zinc silylamido complexes based upon NNO tridentate enolic Schiff base framework have been synthesized and characterized. These complexes were tested for the ring opening polymerization of lactide and e-ca...A series of zinc silylamido complexes based upon NNO tridentate enolic Schiff base framework have been synthesized and characterized. These complexes were tested for the ring opening polymerization of lactide and e-caprolactone, exhibiting notably high activity at ambient temperature, The influence of imine bridge length and substituents of diketone over the course of polymerization was investigated in details. Remarkably, 4a was confirmed to be a rare example of exceedingly active and robust zinc catalysts, achieving major transformation of lactide under extremely low loading （0.025 mol%） within 18 rain. The influence of various monomers as well as the polymerization mechanism have also been discussed.展开更多
Origin and Overview Biodegradable polymer,according to the International Union of Pure and Applied Chemistry(IUPAC),is defined as“polymer susceptible to degradation by biological activity,with the degradation accompa...Origin and Overview Biodegradable polymer,according to the International Union of Pure and Applied Chemistry(IUPAC),is defined as“polymer susceptible to degradation by biological activity,with the degradation accompanied by a lowering of its molar mass”.More specifically,biodegradable polymer should ultimately degrade into CO_(2) and water.展开更多
Copolymerization of propylene oxide(PO)/carbon dioxide(CO_(2))and lactide(LA)is achievable to form new copolymers,combining the advantages of both poly(propylene carbonate)(PPC)and polylactide(PLA).In this study,we de...Copolymerization of propylene oxide(PO)/carbon dioxide(CO_(2))and lactide(LA)is achievable to form new copolymers,combining the advantages of both poly(propylene carbonate)(PPC)and polylactide(PLA).In this study,we designed a dinuclear Salen-Cr(Ⅲ)complex,which showed higher efficiency for copolymerization of PO/CO_(2)and LA than that of mononuclear Salen-Cr(Ⅲ)complex.Besides,we successfully obtained gradient and random copolymers of PPC-PLA in one pot.Furthermore,by adjusting reaction temperature,block ratios of PPC/PLA in copolymers were controllable(block ratio of PPC/PLA=1.0 at 40℃,while block ratio of PPC/PLA=0.5 at room temperature).While increasing the reaction temperature to 60℃,conversion of LA was much faster than that of PO so that gradient copolymers were obtained.展开更多
High solid content CO_(2)-based cationic waterborne polyurethanes(CWPUs)were prepared using CO_(2)-polyols as soft segment and Nmethyl diethanolamine(MDEA)as hydrophilic group.The resulting stable aqueous dispersion d...High solid content CO_(2)-based cationic waterborne polyurethanes(CWPUs)were prepared using CO_(2)-polyols as soft segment and Nmethyl diethanolamine(MDEA)as hydrophilic group.The resulting stable aqueous dispersion displayed a high solid content of 52%with a low MDEA loading of 3.52 wt%.This novel structural CWPU can provide excellent adhesive strength,whose T-peel strength could reach 173.48N/5cm,20%higher than that of ester-based cationic waterborne polyurethane(87.55 N/5cm).The CO_(2)-based CWPU film showed only 2 wt%swelling percentage after 240 min immersion in water,and no change was observed during its immersion in 5 wt%sodium hydroxide solution.The tensile strength of CO_(2)-WPUs dropped slowly to 91.2%after 480 min immersion in a 5 wt%sodium hydroxide solution,whereas that of esterbased CWPUs dropped quickly to 32%after 240 min and their mechanical properties were lost after 360 min immersion.Meanwhile,the retention of the tensile strength of the CO_(2)-CWPUs was 81.5%even after 720 min immersion in 10 wt%H_(2)O_(2) solution,while it was only ca.38%for the ester-based CWPUs.These results indicated that the cationic CO_(2)-based CWPU may be promising waterborne adhesive with outstanding ageing resistance due to its synergistic effect from carbonate and ether groups of CO_(2)-polyol structure.展开更多
基金This work was financially supported by the National Natural Science Foundation of China(Nos.20025414 and 50003009).
文摘Rare-earth ternary catalysts Y（CCl3COO）3-ZnR2-glycerin were prepared for the copolymerization of carbon dioxide and propylene oxide （PO）, where dialkylzincs （ZnR2） were diethylzinc, di（n-propyl）zinc, di（n-butyl）zinc, di（i-propyl）zinc, di（i-butyl）zinc, di（s-butyl）zinc,respectively. The Y（CCl3COO）3-ZnR2-glycerin catalysts displayed the highest catalytic activity at the molar ratio of Y（CCl3COO）3：ZnR2：glycerin = 1：20：10. In the same copolymerization condition, catalysts containing dialkylzincs with branched alkyl group showed lower catalytic activity than that with primary alkyl group. For those catalysts including dialkylzincs with primary alkyl group, their catalytic activity decreases with increasing number of carbon atom in the alkyl group with the following sequence： Y（CCl3COO）3-ZnEt2-glycerin 〉 Y（CCl3COO）3-Zn（n- Pr）2-glycerin〉Y（CCl3COO）3-Zn（n-Bu）2-glycerin. However, the alkyl group in the dialkylzinc does not influence the insertion of PO into the propagation chain end.
基金supported by National Key Research and Development Program of China (No. 2021YFD1700700).
文摘Poly(butylene adipate-co-terephthalate) (PBAT) is currently the largest commercial biodegradable plastics with good toughness and film forming properties, whereas, the inferior barrier and mechanical properties hinder its applications. Biodegradable poly(propylene carbonate) (PPC) with excellent barrier properties and high strength is a natural choice to address above issue. However, it is challenging to improve the compatibility of these two polymers. Herein, we prepared a reactive compatibilizer with double bond side group through terpolymerization of CO_(2)/propylene oxide/glycidyl methacrylate to enhance the properties of PBAT/PPC blends. Upon addition of 1 wt% compatibilizer, the PBAT/PPC blends (75/25, W/W) showed an increased water vapor barrier property changed from 424 g·m^(−2)·d^(−1) to 204 g·m^(−2)·d^(−1) compared to the control sample. Moreover, the tensile strength and elongation at break increased from 24.7 MPa to 30.3 MPa and from 858% to 1142%, respectively. The PBAT/PPC composite also displayed excellent biodegradability under composting conditions, as confirmed by the significantly decreased molecular weight. The present work provides an efficient way to barrier biodegradable film from PBAT of practical utilization.
基金financially supported by the National Natural Science Foundation of China(Nos.U21A2089 and 51873211)。
文摘Aliphatic polyamides have been considered as eco-friendly materials,useful for a wide range of applications.However,it still presents obstacle to produce sustainable aliphatic polyamides from abundant renewable sources.Herein,we describe that 4-hydroxyproline(4-HYP),a renewable resource,was readily converted to its corresponding bicyclic bridged lactam monomers bearing pendant Boc-protected secondary amino group,and oligo-ethylene glycol group.Lithium hexamethyldisilazide(LiHMDS)-mediated polymerization of the resulting monomers exhibited a controlled feature,affording sustainable aliphatic polyamides with number-average molecular weight up to 73 kg/mol and a low molecular weight distribution?<1.28.Overall,this work can lead to a novel kind of functional and sustainable polyamides with potential applications,including degradable plastics,and drug delivery.
基金the Chinese Academy of scienee and technology service network planning(No.KFJSTS-QYZD-140)a program of Cooperation of Hubei Province and Chinese Academy of Sciences,Innovation team project of Beijing Institute of Science and Technology(No.IG201703N)"13^th five-year"Science and Technology Research Program of the Education Department of Jilin Provinee(No.JJKH20190862KJ).
文摘Sustainable blends of poly(propylene carbonate)(PPC)and stereocomplex polylactide(sc-PLA)were prepared by melt blending equimolar poly(L-lactic acid)(PLLA)and poly(D-lactide acid)(PDLA)with PPC to form sc-PLA crystals in situ in the melt blending process.Differential seanning calorimetry analysis revealed that only sc-PLA,no homo-crystallization of PLLA or PDLA,formed in the PPC matrix as the sc-PLA con tent was more than 10 wt%.Very in triguingly,scan ning electronic microscopy observati on showed that sc-PLA was evenly dispersed in the PPC phase as spherical particles and the sizes of sc-PLA particles did not obviously increase with in creasing sc-PLA con tent.As a con seque nee,the rheological properties of PPC were greatly improved by incorporation of sc-PLA.When the sc-PLA con tent was 20 wt%,a percolati on n etwork structure was formed,and the blends showed solid-like behavior.The sc-PLA particles could reinforce the PPC matrix,especially at a temperature above the glass transition temperature of PPC.Moreover,the Vicat softening temperature of PPC/sc-PLA blends could be increased compared with that of neat PPC.
基金financially supported by the National Natural Science Foundation of China(No.51673193)Key Project for Frontier Research(2016)Youth Innovation Promotion Association Chinese Academy of Sciences
文摘Aluminum porphyrin complexes are heavy-metal-free and soil-tolerant green catalysts for the copolymerization of CO2 and propylene oxide（PO）, but they suffer from relatively poor poly（propylene carbonate）（PPC） selectivity. Herein, steric hindrance porphyrin ligand was used to enhance the PPC selectivity. Typically, a bulky anthracene-like group was incorporated into the porphyrin ring to form 5,10,15,20-tetra（1,2,3,4,5,6,7,8-octahydro-1,4：5,8-dimethanoanthracen-9-yl）porphyrin, the aluminum porphyrin complex with this ligand, in combination with bis（triphenylphosphine）iminium chloride as a co-catalyst, produced completely alternate PPC. Additionally, the obtained PPC showed high regioselectivity, with a head-to-tail linkage content（HT） of 92%. Therefore, we demonstrated that introduction of bulky steric ligand into the porphyrin ring could reduce the propylene oxide homopolymerization activity leading to excellent PPC selectivity, and improve regioselectivity for the PO ring-opening during the copolymerization.
基金financially supported by the National Natural Science Foundation of China(Nos.21574124,51503203 and51233004)
文摘A series of zinc silylamido complexes based upon NNO tridentate enolic Schiff base framework have been synthesized and characterized. These complexes were tested for the ring opening polymerization of lactide and e-caprolactone, exhibiting notably high activity at ambient temperature, The influence of imine bridge length and substituents of diketone over the course of polymerization was investigated in details. Remarkably, 4a was confirmed to be a rare example of exceedingly active and robust zinc catalysts, achieving major transformation of lactide under extremely low loading （0.025 mol%） within 18 rain. The influence of various monomers as well as the polymerization mechanism have also been discussed.
文摘Origin and Overview Biodegradable polymer,according to the International Union of Pure and Applied Chemistry(IUPAC),is defined as“polymer susceptible to degradation by biological activity,with the degradation accompanied by a lowering of its molar mass”.More specifically,biodegradable polymer should ultimately degrade into CO_(2) and water.
基金financially supported by the National Key R&D Program of China (No. 2021YFA1501700)the National Natural Science Foundation of China+1 种基金Basic Science Center Program (No.51988102)the National Natural Science Foundation of China (No. 52073272)
文摘Copolymerization of propylene oxide(PO)/carbon dioxide(CO_(2))and lactide(LA)is achievable to form new copolymers,combining the advantages of both poly(propylene carbonate)(PPC)and polylactide(PLA).In this study,we designed a dinuclear Salen-Cr(Ⅲ)complex,which showed higher efficiency for copolymerization of PO/CO_(2)and LA than that of mononuclear Salen-Cr(Ⅲ)complex.Besides,we successfully obtained gradient and random copolymers of PPC-PLA in one pot.Furthermore,by adjusting reaction temperature,block ratios of PPC/PLA in copolymers were controllable(block ratio of PPC/PLA=1.0 at 40℃,while block ratio of PPC/PLA=0.5 at room temperature).While increasing the reaction temperature to 60℃,conversion of LA was much faster than that of PO so that gradient copolymers were obtained.
基金financially supported by the National Natural Science Foundation of China(No.32071686)。
文摘High solid content CO_(2)-based cationic waterborne polyurethanes(CWPUs)were prepared using CO_(2)-polyols as soft segment and Nmethyl diethanolamine(MDEA)as hydrophilic group.The resulting stable aqueous dispersion displayed a high solid content of 52%with a low MDEA loading of 3.52 wt%.This novel structural CWPU can provide excellent adhesive strength,whose T-peel strength could reach 173.48N/5cm,20%higher than that of ester-based cationic waterborne polyurethane(87.55 N/5cm).The CO_(2)-based CWPU film showed only 2 wt%swelling percentage after 240 min immersion in water,and no change was observed during its immersion in 5 wt%sodium hydroxide solution.The tensile strength of CO_(2)-WPUs dropped slowly to 91.2%after 480 min immersion in a 5 wt%sodium hydroxide solution,whereas that of esterbased CWPUs dropped quickly to 32%after 240 min and their mechanical properties were lost after 360 min immersion.Meanwhile,the retention of the tensile strength of the CO_(2)-CWPUs was 81.5%even after 720 min immersion in 10 wt%H_(2)O_(2) solution,while it was only ca.38%for the ester-based CWPUs.These results indicated that the cationic CO_(2)-based CWPU may be promising waterborne adhesive with outstanding ageing resistance due to its synergistic effect from carbonate and ether groups of CO_(2)-polyol structure.
