The photoinduced bulk polymerization of a reactive-hindered amine light stabilizers (r-HALS), 4-acryloyl-2, 2, 6,6-tetramethylpiperidinyl (ATMP), was performed at 80 C by using a DPC technique. An unique periodic expo...The photoinduced bulk polymerization of a reactive-hindered amine light stabilizers (r-HALS), 4-acryloyl-2, 2, 6,6-tetramethylpiperidinyl (ATMP), was performed at 80 C by using a DPC technique. An unique periodic exponential attenuation-type oscillating curve was found when the polymerization was carried out in air, but this phenomenon was not found in nitrogen. It is supposed that this unique kinetic performance may be attributed to nitroxyl radicals that are produced in situ from the oxidation of ATMP. ATMP polymer with narrow polydispersity (d = 1.03) can be obtained by photoinduced solution polymerization of ATMP. The signal detected in ESR may be assigned to the nitroxyl radicals in the matrix of ATMP polymer. Since this kind of recycling of nitroxyl radicals is well documented for the photostabilizing mechanism of HALS, the present results may serve as a kinetic evidence for this mechanism.展开更多
A new nitrogen-containing epoxy resin (XT resin) was synthesized from chain extension of xylenephenolformaldehyde resin (XPF) and triglycidyl isocyanurate (TGIC) in the presence of base catalyst. FT-IR and H-NMR ana...A new nitrogen-containing epoxy resin (XT resin) was synthesized from chain extension of xylenephenolformaldehyde resin (XPF) and triglycidyl isocyanurate (TGIC) in the presence of base catalyst. FT-IR and H-NMR analysis confirmed the chemical structure of XT resin. It was 1 cured with dicyandiamide (DICY) and diaminodiphenyl sulfone (DDS). Dynamic mechanical analysis (DMA) results showed that the introduction of triazine ring provides epoxy polymer with good thermal stability. Furthermore, high char yields at 800℃ in thermogravimetric (TGA) analysis indicated that XT resin had potential flame retardance.展开更多
Montmorillonite(MMT) modified with sodium silicate can change the arrangement of its layers from edge-face and edge-edge to face-face. With the fine dispersion of the modified MMT in water,the cation-exchange reaction...Montmorillonite(MMT) modified with sodium silicate can change the arrangement of its layers from edge-face and edge-edge to face-face. With the fine dispersion of the modified MMT in water,the cation-exchange reaction was carried out with cetyltrimethyl ammonium bromide(CTAB) to obtain organo-montmorillonite(OMMT). As OMMT was uniformly dispersed in methyl methacrylate(MMA) monomer,PMMA/OMMT nanocomposites were formed via a common emulsion polymerization. The products were extracted with hot acetone and characterized by FTIR,molecular weight,X-ray diffraction(XRD),transmission electron microscopy(TEM),DSC and TGA. These results show that most of the OMMT layers have been exfoliated,while the thermal stability is increased obviously. By means of FTIR spectral analysis,the ratios of the macromolecular radicals′ termination of disproportionation patterns to combination are increased with the addition of OMMT. This result further confirms the increase of the thermal degradation temperatures and glass transition temperatures of the PMMA/OMMT nanocomposites.展开更多
A new economic and convenient method to modify the surface of microporous polypropylene (PP) membranes with phospholipid polymer was given. The process included the photo-irradiated graft polymerization of N,N-dimethy...A new economic and convenient method to modify the surface of microporous polypropylene (PP) membranes with phospholipid polymer was given. The process included the photo-irradiated graft polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA) and the ring-opening reaction of the grafted polyDMAEMA with 2-alkyloxy-2-oxide-1,3,2-dioxo-phospholanes (AOP). Four AOPs, whose alkyloxy groups consisted of dodecyl, tetradecyl, hexadecyl and octadecyl moieties, were used to convert the grafted polyDMAEMA to phospholipid polymers. FT-IR spectra confirmed the chemical change of membrane surface. Platelets adhesion experiment indicated that PP membrane with excellent blood compatible surface could be fabricated by this method.展开更多
Dihydroxy capped triblock oligomers of 2, 2-dimethyltrimethylene carbonate (DTC) andε-caprolactone (CL) with number-average molecular weight from 3,000 to 12,000 g/mol have beensynthesized by alkyl glycol initiator i...Dihydroxy capped triblock oligomers of 2, 2-dimethyltrimethylene carbonate (DTC) andε-caprolactone (CL) with number-average molecular weight from 3,000 to 12,000 g/mol have beensynthesized by alkyl glycol initiator in the presence of yttrium tri(2, 6-di-tert-butyl-4-methylphenolate)s (Y(OAr)3) catalyst. They are expected to be used as macroinitiators for thedesign of new polymeric materials.展开更多
To improve the hydrophilicity of polyacrylonitrile-based membranes, sugar moieties were incorporated into acrylonitrile-based copolymers via the radical copolymerization of α-allyl glucoside(AG) with acrylonitrile(AN...To improve the hydrophilicity of polyacrylonitrile-based membranes, sugar moieties were incorporated into acrylonitrile-based copolymers via the radical copolymerization of α-allyl glucoside(AG) with acrylonitrile(AN) with 2,2′-azobis-iso-butyronitrile(AIBN) as the initiator in dimethyl sulphoxide(DMSO). It was found that the yield increased with the increase of the initiator concentration and reaction time, while it decreased with the increase of the monomer molar ratio of AG to AN. Raising the AG proportion in the monomer mixture resulted in the increase of the AG content in the copolymer. M_v of the copolymers decreased with increasing the AG monomer fraction in feed. The copolymers were fabricated into dense membranes and their surface properties were studied by means of the water contact angle measurement and platelet adhesion tests. It was found that the static water contact angle on the membrane decreased significantly from 70° to 33° with the increase of the AG content. The adhesive number of platelets on the membrane surface also decreased significantly with increasing AG content in the copolymers. These results demonstrate that the hydrophilicity and biocompatibility of the acrylonitrile-based copolymer membranes could be improved efficiently by the copolymerization of acrylonitrile with vinyl carbohydrates.展开更多
Poly (trimethylene-co-ethylene terephthalate) with various compositions of diol has been synthesized. The crystallization of copolyesters with high comonomer content was observed by both wide-angle X-ray diffraction (...Poly (trimethylene-co-ethylene terephthalate) with various compositions of diol has been synthesized. The crystallization of copolyesters with high comonomer content was observed by both wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). It was found that the copolyesters become less crystallizable with the involvement of the comonomer, the crystals of crystallizable copolyesters come from PTT or PET homopolymers. The glass transition temperature (Tg) of the copolyester increases with increasing PET component in the copolyester, and the relationship between Tg and composition obey both Fox equation and additive law, the former is better in describing this relationship.展开更多
Biphenyltetracarboxylic dianhydride (2,2',3,3' BPDA), C 16 H 6O 6, M r =294.21, monoclinic, P2 1/c, a=11.694(2), b=8.111(2), c=13 494(3) , β=103.47(3)°, V=1244.7(4) 3, Z=4, D c =1.57...Biphenyltetracarboxylic dianhydride (2,2',3,3' BPDA), C 16 H 6O 6, M r =294.21, monoclinic, P2 1/c, a=11.694(2), b=8.111(2), c=13 494(3) , β=103.47(3)°, V=1244.7(4) 3, Z=4, D c =1.570 g/cm 3 , F (000)=450, Mo Kα radiation( λ =0.71073), μ (Mo Kα )=0.092 mm -1 , R =0.0329 for 2180 observed reflections 〔 I>2σ(I) 〕. 3,3',4,4' Biphenyltetracarboxylic dianhydride (3,3',4,4' BPDA), C 16 H 6O 6, M r =294.21, monoclinic, P2 1/n, a=6.8720(14), b=5.1870(10), c=17.288(4), β=94.96(3)°, V= 613.9(2) 3, Z=2, D c =1 592 gcm -3 , F(000)=300 , μ (Mo Kα )=0.125mm -1 , R =0.0331 for 1079 observed reflections〔 I>2σ(I) 〕. The dianhydride isomers have different symmetry caused by alternating two anhydride group positions and the dihedral angle between the two phenyl rings are 62.9°for 2,2',3,3', BPDA and 0°for 3,3',4,4' BPDA respectively.展开更多
The micropattern observed in the amorphous azobenzene polymer film by degenerated four-wave mixing has been reported. Patterns with well-defined structures are examined with the scanning electron microscopy and the po...The micropattern observed in the amorphous azobenzene polymer film by degenerated four-wave mixing has been reported. Patterns with well-defined structures are examined with the scanning electron microscopy and the polarizing optical microscopy. It is demonstrated that the control of photoinduced micropattern in the azobenzene polymer film is possible by using appropriate polarized writing beams with total incident power exceeding a certain threshold.展开更多
基金the National Natural Science Foundation of China(No.20274023)key project foundation of National Ministry of Education(No.02114)Guangdong Province Natural Science Foundation of China(No.021241)for supporting this work.
文摘The photoinduced bulk polymerization of a reactive-hindered amine light stabilizers (r-HALS), 4-acryloyl-2, 2, 6,6-tetramethylpiperidinyl (ATMP), was performed at 80 C by using a DPC technique. An unique periodic exponential attenuation-type oscillating curve was found when the polymerization was carried out in air, but this phenomenon was not found in nitrogen. It is supposed that this unique kinetic performance may be attributed to nitroxyl radicals that are produced in situ from the oxidation of ATMP. ATMP polymer with narrow polydispersity (d = 1.03) can be obtained by photoinduced solution polymerization of ATMP. The signal detected in ESR may be assigned to the nitroxyl radicals in the matrix of ATMP polymer. Since this kind of recycling of nitroxyl radicals is well documented for the photostabilizing mechanism of HALS, the present results may serve as a kinetic evidence for this mechanism.
文摘A new nitrogen-containing epoxy resin (XT resin) was synthesized from chain extension of xylenephenolformaldehyde resin (XPF) and triglycidyl isocyanurate (TGIC) in the presence of base catalyst. FT-IR and H-NMR analysis confirmed the chemical structure of XT resin. It was 1 cured with dicyandiamide (DICY) and diaminodiphenyl sulfone (DDS). Dynamic mechanical analysis (DMA) results showed that the introduction of triazine ring provides epoxy polymer with good thermal stability. Furthermore, high char yields at 800℃ in thermogravimetric (TGA) analysis indicated that XT resin had potential flame retardance.
文摘Montmorillonite(MMT) modified with sodium silicate can change the arrangement of its layers from edge-face and edge-edge to face-face. With the fine dispersion of the modified MMT in water,the cation-exchange reaction was carried out with cetyltrimethyl ammonium bromide(CTAB) to obtain organo-montmorillonite(OMMT). As OMMT was uniformly dispersed in methyl methacrylate(MMA) monomer,PMMA/OMMT nanocomposites were formed via a common emulsion polymerization. The products were extracted with hot acetone and characterized by FTIR,molecular weight,X-ray diffraction(XRD),transmission electron microscopy(TEM),DSC and TGA. These results show that most of the OMMT layers have been exfoliated,while the thermal stability is increased obviously. By means of FTIR spectral analysis,the ratios of the macromolecular radicals′ termination of disproportionation patterns to combination are increased with the addition of OMMT. This result further confirms the increase of the thermal degradation temperatures and glass transition temperatures of the PMMA/OMMT nanocomposites.
文摘A new economic and convenient method to modify the surface of microporous polypropylene (PP) membranes with phospholipid polymer was given. The process included the photo-irradiated graft polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA) and the ring-opening reaction of the grafted polyDMAEMA with 2-alkyloxy-2-oxide-1,3,2-dioxo-phospholanes (AOP). Four AOPs, whose alkyloxy groups consisted of dodecyl, tetradecyl, hexadecyl and octadecyl moieties, were used to convert the grafted polyDMAEMA to phospholipid polymers. FT-IR spectra confirmed the chemical change of membrane surface. Platelets adhesion experiment indicated that PP membrane with excellent blood compatible surface could be fabricated by this method.
基金The authors are grateful to the financial supports by the National Natural Science Foundation of China(No.20174033)the Special Fund for Major State Basic Research Project(G1999064801)the Committee of Science and Technology of Zhejiang Province.
文摘Dihydroxy capped triblock oligomers of 2, 2-dimethyltrimethylene carbonate (DTC) andε-caprolactone (CL) with number-average molecular weight from 3,000 to 12,000 g/mol have beensynthesized by alkyl glycol initiator in the presence of yttrium tri(2, 6-di-tert-butyl-4-methylphenolate)s (Y(OAr)3) catalyst. They are expected to be used as macroinitiators for thedesign of new polymeric materials.
文摘To improve the hydrophilicity of polyacrylonitrile-based membranes, sugar moieties were incorporated into acrylonitrile-based copolymers via the radical copolymerization of α-allyl glucoside(AG) with acrylonitrile(AN) with 2,2′-azobis-iso-butyronitrile(AIBN) as the initiator in dimethyl sulphoxide(DMSO). It was found that the yield increased with the increase of the initiator concentration and reaction time, while it decreased with the increase of the monomer molar ratio of AG to AN. Raising the AG proportion in the monomer mixture resulted in the increase of the AG content in the copolymer. M_v of the copolymers decreased with increasing the AG monomer fraction in feed. The copolymers were fabricated into dense membranes and their surface properties were studied by means of the water contact angle measurement and platelet adhesion tests. It was found that the static water contact angle on the membrane decreased significantly from 70° to 33° with the increase of the AG content. The adhesive number of platelets on the membrane surface also decreased significantly with increasing AG content in the copolymers. These results demonstrate that the hydrophilicity and biocompatibility of the acrylonitrile-based copolymer membranes could be improved efficiently by the copolymerization of acrylonitrile with vinyl carbohydrates.
文摘Poly (trimethylene-co-ethylene terephthalate) with various compositions of diol has been synthesized. The crystallization of copolyesters with high comonomer content was observed by both wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry (DSC). It was found that the copolyesters become less crystallizable with the involvement of the comonomer, the crystals of crystallizable copolyesters come from PTT or PET homopolymers. The glass transition temperature (Tg) of the copolyester increases with increasing PET component in the copolyester, and the relationship between Tg and composition obey both Fox equation and additive law, the former is better in describing this relationship.
文摘Biphenyltetracarboxylic dianhydride (2,2',3,3' BPDA), C 16 H 6O 6, M r =294.21, monoclinic, P2 1/c, a=11.694(2), b=8.111(2), c=13 494(3) , β=103.47(3)°, V=1244.7(4) 3, Z=4, D c =1.570 g/cm 3 , F (000)=450, Mo Kα radiation( λ =0.71073), μ (Mo Kα )=0.092 mm -1 , R =0.0329 for 2180 observed reflections 〔 I>2σ(I) 〕. 3,3',4,4' Biphenyltetracarboxylic dianhydride (3,3',4,4' BPDA), C 16 H 6O 6, M r =294.21, monoclinic, P2 1/n, a=6.8720(14), b=5.1870(10), c=17.288(4), β=94.96(3)°, V= 613.9(2) 3, Z=2, D c =1 592 gcm -3 , F(000)=300 , μ (Mo Kα )=0.125mm -1 , R =0.0331 for 1079 observed reflections〔 I>2σ(I) 〕. The dianhydride isomers have different symmetry caused by alternating two anhydride group positions and the dihedral angle between the two phenyl rings are 62.9°for 2,2',3,3', BPDA and 0°for 3,3',4,4' BPDA respectively.
基金supported by the National Natural Science Foundation of China(Grant No.196040l5)the Natural Science Foundation of Guangdong Province(Grant NOs.980346 and 001249).
文摘The micropattern observed in the amorphous azobenzene polymer film by degenerated four-wave mixing has been reported. Patterns with well-defined structures are examined with the scanning electron microscopy and the polarizing optical microscopy. It is demonstrated that the control of photoinduced micropattern in the azobenzene polymer film is possible by using appropriate polarized writing beams with total incident power exceeding a certain threshold.
