Three polyamidoamine(PAMAM) dendrimers have been synthesized by divergence method with ethylenediamine as core. The surface tensions of aqueous solution of different generation PAMAM were determined by traditional sur...Three polyamidoamine(PAMAM) dendrimers have been synthesized by divergence method with ethylenediamine as core. The surface tensions of aqueous solution of different generation PAMAM were determined by traditional surfactant method. The results showed that the whole PAMAM doesn′t have surface acti- vity and the half PAMAM have certain surface activity. Their critical micelle concentrations(CMC) were obtained from surface tension curves, and the hydrophile-lipophile balance number(HLB), saturated adsorption capacity, molecular cross section area and molecular diameter were calculated. The results revealed that the molecular diameter of 0.5G, 1.5G and 2.5G PAMAM were 0.743, 0.998 and 1.371 nanometer, respe- ctively. The dendrimer obtained was also proved to be of nanometer order.展开更多
Novel physically cross-linked hydrogels, composed of PVA and hydroxy-terminated polyamidoamine(PAMAM) dendrimer G6-OH, were prepared by cyclic freezing/thawing treatment of aqueous solutions containing PVA and G6-OH. ...Novel physically cross-linked hydrogels, composed of PVA and hydroxy-terminated polyamidoamine(PAMAM) dendrimer G6-OH, were prepared by cyclic freezing/thawing treatment of aqueous solutions containing PVA and G6-OH. FTIR analysis indicates that PAMAM dendrimer G6-OH was successfully introduced into PVA hydrogels. Higher contents of G6-OH in PVA/G6-OH hydrogels resulted in higher swelling ratios, and faster reswelling rates. With the increase of freezing/thawing cyclic times, the swelling ratios and reswelling rates of PVA/G6-OH hydrogels decreased, which is similar to that of physically cross-linked PVA hydrogel.展开更多
制备了聚酰胺-胺(PAMAM)-2-吡啶甲醛(Py)席夫碱树枝状大分子及其钯配合物。通过红外、核磁共振、元素分析、等离子耦合原子发散光谱及热重-差热等分析手段对其进行了结构确证。研究了PAMAM-2-吡啶甲醛席夫碱钯配合物在Heck反应中的催化...制备了聚酰胺-胺(PAMAM)-2-吡啶甲醛(Py)席夫碱树枝状大分子及其钯配合物。通过红外、核磁共振、元素分析、等离子耦合原子发散光谱及热重-差热等分析手段对其进行了结构确证。研究了PAMAM-2-吡啶甲醛席夫碱钯配合物在Heck反应中的催化性能。以三乙胺(Et_3N)作为缚酸剂,碘代苯(Ph I):10 mmol,n(Ph I)∶n(AA)∶n(Et_3N)为1∶1.4∶2.5,n(Pd)=6.1×10-3mmol(5.0G PAMAMPy-Pd),在5 m L DMF中,100℃和N_2气保护下反应25 min,产率90.1%。催化剂经过简单的过滤可回收,重复使用3次产率仍可达82.0%。展开更多
文摘Three polyamidoamine(PAMAM) dendrimers have been synthesized by divergence method with ethylenediamine as core. The surface tensions of aqueous solution of different generation PAMAM were determined by traditional surfactant method. The results showed that the whole PAMAM doesn′t have surface acti- vity and the half PAMAM have certain surface activity. Their critical micelle concentrations(CMC) were obtained from surface tension curves, and the hydrophile-lipophile balance number(HLB), saturated adsorption capacity, molecular cross section area and molecular diameter were calculated. The results revealed that the molecular diameter of 0.5G, 1.5G and 2.5G PAMAM were 0.743, 0.998 and 1.371 nanometer, respe- ctively. The dendrimer obtained was also proved to be of nanometer order.
文摘Novel physically cross-linked hydrogels, composed of PVA and hydroxy-terminated polyamidoamine(PAMAM) dendrimer G6-OH, were prepared by cyclic freezing/thawing treatment of aqueous solutions containing PVA and G6-OH. FTIR analysis indicates that PAMAM dendrimer G6-OH was successfully introduced into PVA hydrogels. Higher contents of G6-OH in PVA/G6-OH hydrogels resulted in higher swelling ratios, and faster reswelling rates. With the increase of freezing/thawing cyclic times, the swelling ratios and reswelling rates of PVA/G6-OH hydrogels decreased, which is similar to that of physically cross-linked PVA hydrogel.
文摘制备了聚酰胺-胺(PAMAM)-2-吡啶甲醛(Py)席夫碱树枝状大分子及其钯配合物。通过红外、核磁共振、元素分析、等离子耦合原子发散光谱及热重-差热等分析手段对其进行了结构确证。研究了PAMAM-2-吡啶甲醛席夫碱钯配合物在Heck反应中的催化性能。以三乙胺(Et_3N)作为缚酸剂,碘代苯(Ph I):10 mmol,n(Ph I)∶n(AA)∶n(Et_3N)为1∶1.4∶2.5,n(Pd)=6.1×10-3mmol(5.0G PAMAMPy-Pd),在5 m L DMF中,100℃和N_2气保护下反应25 min,产率90.1%。催化剂经过简单的过滤可回收,重复使用3次产率仍可达82.0%。
