共查询到17条相似文献,搜索用时 143 毫秒
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通过酸碱处理和机械研磨结合的方法制备纳米纤维素(CNFs),并利用冻融循环法分别制备了聚乙烯醇(PVA)和纳米纤维素/聚乙烯醇(CNFs/PVA)复合水凝胶,以及聚乙二醇(PEG)改性PVA和CNFs/PVA复合水凝胶。考察不同配方下复合水凝胶的微观形貌变化,并对复合水凝胶的溶胀性能、压缩强度及热稳定性能进行研究。结果表明,CNFs与PEG对PVA水凝胶的微观形貌均有改善作用,加入PEG后形成的PEG/PVA凝胶产生明显的三维网络结构。当PEG与CNFs同时加入到PVA凝胶后形成的CNFs-PEG/PVA凝胶具有均匀的互穿孔洞结构,此时复合水凝胶的孔隙率最高((67.5±4.3)%),溶胀度最好(980%),且压缩强度较PVA水凝胶也有所提升。PEG对复合凝胶的热稳定性无影响,而加入CNFs后,CNFs-PEG/PVA复合凝胶的初始热分解温度从235℃上升至300℃,显著提高了PVA凝胶的热稳定性。 相似文献
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以聚乙烯醇(PVA)为原料,氧化石墨烯(GO)和羟基磷灰石(HA)为共掺杂物,先以戊二醛作为交联剂,采用化学交联法制备了GO/HA/PVA单网络单交联复合水凝胶,再通过循环冷冻-解冻技术使PVA聚合物链间进一步发生氢键交联,制备得到GO/HA/PVA双网络双交联复合水凝胶。采用HRSEM、XRD表征了水凝胶的微观形貌和晶相结构,并研究了GO与PVA、HA与PVA在不同质量比及不同冷冻-解冻循环次数时制备所得GO/HA/PVA复合水凝胶的力学性能。结果表明:随着GO与PVA质量百分比的增加(0%~2.6%),该凝胶拉伸力学强度不断增强;随着HA与PVA质量比的增加(0.22~1.10),该凝胶的拉伸强度先增强后减弱;随着冷冻-解冻循环次数增加(0次、3次、7次)该凝胶的拉伸强度逐渐增强,弹性模量也逐渐提高。当GO与PVA质量百分比为1.9%、HA与PVA质量比为0.66、冷冻-解冻循环次数N=7次时,制备所得凝胶的拉伸力学性能最优(拉伸强度为695 kPa,断裂应变为286%,弹性模量为78 kPa)。此外,深入研究了不同冷冻-解冻循环次数对水凝胶含水率和溶胀率的影响规律。结果表明:不同冷冻-解冻循环次数(0次、3次、7次)的凝胶含水率为79.3%~81.7%,平衡溶胀率为50.1%~72%,且均在60 min后达到溶胀平衡。该水凝胶有望作为软骨替代材料应用于临床医学领域。 相似文献
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《高分子材料科学与工程》2015,(6)
采用冷冻-解冻方法制备了物理交联的聚乙烯醇/氧化石墨烯复合水凝胶。采用热失重、X射线衍射、差示扫描量热、扫描电镜、力学性能、溶胀性能及离子强度敏感性等分析对制备的复合水凝胶进行了表征,研究了氧化石墨烯(GO)含量、冷冻-解冻循环次数、聚乙烯醇(PVA)浓度对复合水凝胶性能的影响。研究结果表明,复合水凝胶呈现出三维多孔网络结构;随着GO含量的增加,水凝胶的热稳定性增强、熔融温度上升,拉伸强度和压缩强度也得到明显提高,说明GO在复合水凝胶中起到了物理交联剂的作用;复合水凝胶的平衡溶胀比随着GO含量的增加而增大,但当GO的质量分数超过0.4%时逐渐减小;增加冷冻-解冻循环次数或PVA浓度,水凝胶的拉伸强度和压缩强度增大,力学性能得到显著改善。 相似文献
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PVA/P(AA-AM)复合水凝胶的制备及性能 总被引:2,自引:0,他引:2
采用水溶液聚合方法合成了不同组成的丙烯酸-丙烯酰胺共聚物(P(AA-AM))。将聚乙烯醇(PVA)与所合成的P(AA-AM)共混,以戊二醛为交联剂,制备出了不同结构的PVA/P(AA-AM)复合水凝胶。采用扫描电镜观察了凝胶形貌,研究了复合水凝胶的结构与性能关系。结果表明,复合水凝胶溶胀性能与所用交联剂加量有关,复合水凝胶的溶胀度随着交联剂加量增加先增大后减小,在交联剂加量为0.5%时水凝胶溶胀度达到最大值。复合凝胶中的聚合物组成对溶胀度影响显著,随着P(AA-AM)含量提高,水凝胶的溶胀度逐渐增大。适当结构的复合水凝胶具有pH敏感性,敏感程度随着凝胶中P(AA-AM)含量的增加而增强。 相似文献
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利用冷冻-解冻法制备了细菌纤维素(BC)/聚乙烯醇(PVA)双网络复合水凝胶,研究不同BC含量及循环周期对BC/PVA复合水凝胶力学性能和溶胀特性的影响,结果表明,随着BC含量的增多,复合水凝胶的含水率、平衡溶胀比、拉伸强度和压缩强度与普通的PVA水凝胶相比均有一定程度的提高;综合考虑,当BC含量为4%时,各项性能均达到最佳值;随着循环次数的增多,水凝胶内部的物理交联点增多,导致水凝胶的含水率下降,拉伸强度和压缩强度则有明显的上升趋势。SEM观察的结果与之前的分析是一致的。 相似文献
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采用白炭黑(WCB)与聚乙烯醇(PVA)原位交联制备PVA/WCB复合水凝胶。结果发现WCB表面的邻二羟基与硼酸的交联反应增加了PVA交联反应时硼酸的消耗量;WCB表面对硼酸的吸附作用加速硼酸扩散渗入凝胶内部,促进PVA的交联反应,当WCB含量为1.0%(质量分数)时,交联反应速率常数达到最大值5.05h-1。应变扫描中复合水凝胶的储能模量明显大于其损耗模量,证明网络结构的存在,随WCB含量增加,凝胶线性粘弹增强比上升,WCB的增强效率为30.19。适量WCB能提高PVA凝胶小球的耐水力冲击性能及拉伸力学性能。WCB的加入使复合水凝胶的网孔尺寸增大、孔壁变薄、开孔增多、平衡溶胀率增加,将其固定化微生物用于污水处理,有效提高了污水处理效率,当WCB含量为2.5%(质量分数)时PVA固定化微生物水凝胶的COD去除率为75.73%。 相似文献
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通过水-乙醇和水-正丙醇两种不同的溶剂体系制备高分子量和不同氧化度的氧化海藻酸钠(OSA),然后引入聚丙烯酰胺(PAM)交联网络结构,通过二步法获得OSA/PAM复合水凝胶。探讨了不同反应体系下,HCl体积分数对OSA分子量的影响以及氧化剂(高碘酸钠NaIO_4)添加量、反应时间对OSA氧化度的影响规律。结果表明:在水-正丙醇体系下,HCl体积分数为24vol%时,氧化海藻酸钠的分子量达到170 000;调节NaIO_4的添加量和反应时间可以控制OSA的氧化度在10%~85%范围内变化。在此基础上对OSA/PAM复合水凝胶的溶胀率和力学性能进行了探讨,发现氧化度10%的复合水凝胶48h后的溶胀率达1 777%,断裂强度为0.11MPa,随着OSA氧化度的增大,OSA/PAM复合水凝胶的溶胀率增大,而拉伸强度逐渐减小。 相似文献
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在聚乙烯醇(PVA)水凝胶的网络中引入完全生物降解的聚对二氧环己酮(PPDO),采用冻融法制备出生物降解周期可控的PPDO/PVA复合水凝胶。通过调整低分子量PPDO与高分子量PVA之间的比例,使PPDO柔性分子链与PVA分子链之间形成聚合物网络互穿结构,实现改善水凝胶力学性能和生物降解性能的目的。采用红外光谱、扫描电镜和万能试验机对水凝胶进行了结构表征和性能测试;并通过溶胀性能及失水性能测试、降解性能测试和抑菌性测试对水凝胶进行了研究。结果表明,PPDO/PVA复合水凝胶呈现出孔隙均匀的三维网络结构,拉伸强度和压缩强度与纯PVA水凝胶相比提高了1~3倍;在37℃的PBS缓冲溶液中降解,降解速率明显提升,35 d可以降解45%,且在伤口愈合的周期内保持优异的力学强度。平板细菌培养实验证明了复合水凝胶具有抑菌的特性。PPDO/PVA复合水凝胶在伤口敷料领域具有广泛的应用前景。 相似文献
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Kemin Liu Yubao Li Fenglan Xu Yi Zuo Li Zhang Huanan Wang Jianguo Liao 《Materials science & engineering. C, Materials for biological applications》2009,29(1):261-266
Graphite/poly (vinyl alcohol) (PVA) hydrogel composites, which were designed as the porous ringy skirt surrounding the transparent core of a novel artificial cornea, were prepared by using the freeze/thawing process and the particle-leaching technique. The properties of the composites, including the water content, the mechanical strength, the porous architecture and the interactions between the graphite and PVA, were investigated. The tissue responses to the composite and pure PVA hydrogel were studied by in vivo implantation in the dorsal muscles of mice. The results showed that chemical interactions were present between the graphite and PVA in the composite, which benefited the combination of the two phases and enhanced the uniform distribution of graphite particles in the PVA matrix. However, the present of graphites in the PVA hydrogels reduced the tensile strength, elongation at break and water content of the composite. Moreover, the porous graphite/PVA hydrogel composite had interconnective pore structure with high porosity and enough mechanical strength. According to the histological analysis of 1 week and 12 weeks post-implantation, the graphite/PVA hydrogel composites showed less inflammatory reactions than the PVA hydrogels at the 1 week post-implantation. Moreover, compared to pure PVA hydrogel, the graphite/PVA hydrogel composite exhibited enhanced migration and infiltration of cells, and more neovascularization and tissue ingrowth. These in vivo characteristics will be beneficial for the long-term biofixation of artificial cornea. Therefore, the porous graphite/PVA hydrogel composite has a potential to be used as novel artificial cornea skirt. 相似文献
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采用聚乙烯醇为基质材料制备了聚苯胺/聚乙烯醇(PANI/PVA)复合膜,讨论了PANI与PVA质量比、膜干燥温度对复合膜性能的影响,并对PVA膜、HCl掺杂PANI膜以及PANI/PVA复合膜的拉伸断裂强度、断裂伸长率、电导率以及热稳定性作了比较。结果表明:PVA膜的拉伸断裂强度、断裂伸长率最强,但是电导率最小;PANI/PVA复合膜电导率最大,其拉伸断裂强度、断裂伸长率比未加PVA的HCl掺杂PANI膜都得到了大大提高。在180℃之前,PVA膜最稳定,HCl掺杂PANI膜稳定性最差;在260℃之后,HCl掺杂PANI膜最稳定,PVA膜稳定性最差。 相似文献
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采用半互穿网络技术和原位自由基聚合将生物相容性和吸水性优良的丝胶蛋白(SS)引入聚异丙基丙烯酰胺-硅酸镁锂(Poly(NIPAm-LMSH))纳米复合凝胶网络,制得高溶胀度和快速响应的SS/Poly(NIPAm-LMSH)纳米复合凝胶,研究了丝胶含量对纳米复合凝胶的孔洞形态、溶胀动力学、结晶结构、相容性和稳定性的影响。结果表明:冷冻干燥后的SS/Poly(NIPAm-LMSH)水凝胶呈多孔结构,孔洞尺寸为20~30 μm,孔壁薄,为1~4 μm,且随丝胶含量增加而由多面体结构变为狭长形的层状结构。相比于溶胀平衡的纯纳米复合凝胶,丝胶的引入显著提高了其溶胀度,溶胀初期属于Non-Fickian扩散,37 ℃ 10 min内即可失去90%的水。丝胶在凝胶中具有良好的相容性,SS/Poly(NIPAm-LMSH)纳米复合凝胶的 Tg为141~144 ℃,最大热分解温度为365~373 ℃,质量残留率随丝胶含量的增加而增大。 相似文献
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目的研究聚乙二醇(PEG)的加入对复合凝胶微观结构、溶胀性能和热稳定性的影响,扩大复合凝胶在包装领域的应用。方法以PEG为致孔剂,纳米纤维素(CNFs)为增强相,利用物理交联法制备出多孔聚乙烯醇/纳米纤维素复合水凝胶。结果 PEG作为致孔剂时可制得网络互穿结构的多孔水凝胶,复合凝胶的溶胀度可达到1000,相比于纯PVA水凝胶有极大的提高,同时加入CNFs的聚乙烯醇凝胶与纯的聚乙烯醇凝胶相比具有更好的热稳定性。结论这种有着高溶胀性和良好热稳定性的多孔复合凝胶可用于包装产品的保鲜与物流防护。 相似文献
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《Materials Letters》2007,61(8-9):1704-1706
In this paper, carbon nanotubes (CNTs) were added into poly(vinyl alcohol) (PVA) hydrogels to modify their mechanical properties. A series of CNT/PVA hybrid hydrogels were prepared by freezing/thawing method. The mechanical and swelling properties of all hybrid hydrogels are better than those of the original PVA hydrogel. Especially, for CNTP-0.5 specimen with 0.5% w/w CNTs, its tensile modulus, tensile strength and strain at break are increased by 78.2%, 94.3% and 12.7%, respectively. And its swelling behavior is different from that of the pure PVA hydrogel. Its final swelling ratios at room temperature and 310 K are increased by 35.7% and 44.9%, respectively. 相似文献
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Zhicun WANG Xiaoman HAN Yixi WANG Kenan MEN Lin CUI Jianning WU Guihua MENG Zhiyong LIU Xuhong GUO 《材料科学前沿(英文版)》2019,13(1):54-63
A polyacrylic acid(PAA)/gelatin(Gela)/polyvinyl alcohol(PVA)hydrogel was prepared by copolymerization,cooling,and freezing/thawing methods.This triplenetwork(TN)structure hydrogel displayed superior mechanical properties,low swelling ratio and self-healing properties,The superior mechanical properties are attributed to the triple helix association of Gela and PVA crystallites by reversible hydrogen bonding.The characterization results indicated that the fracture stress and the strain were 808 kPa and 370% respectively,while the compression strength could reach 4443 kPa and the compressive modulus was up to 39 MPa under the deformation of 90%.The hydrogen bonding in PVA contributed to maintain and improve the self-healing ability of hydrogels.Every type of hydrogels exhibited a higher swelling ratio under alkaline conditions,and the swelling ratios of PAA,PAA/PVA and PAA/Gela hydrogels were 27.71,12.30 and 9.09,respectively.The PAA/Gela/PVA TN hydrogel showed the lowest swelling ratio(6.57)among these hydrogels.These results indicate that the novel TN hydrogels possess good environmental adaptability and have potential applications in the biomedical engineering and sensor field. 相似文献
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Multiwalled carbon nanotubes (MWCNTs) were added to polyacrylamide (PAM) hydrogels in different proportions to tune their electrical and mechanical properties. The choice of MWCNTs as a reinforcement is justified by the fact that these are highly conducting, fairly stable and flexible particles. A series of MWCNT/PAM hydrogels were prepared by freezing method. The characteristic absorption peaks at 1480 and 1213 cm?1 in the FTIR spectra reveal that MWCNTs are embedded in the PAM hydrogels. Powder x-ray diffractograms and thermogravimetric analysis (TGA) images show that the MWCNT/PAM hydrogels are crystalline, more thermally stable and have a higher electrical conductivity than a traditional PAM hydrogel. Scanning electron micrographs reveal about reduced pore size, homogeneous and denser texture. The swelling properties of all these hybrid hydrogels were found to be better than those of the parent PAM hydrogel. The Li–Tanaka equation was employed to produce the swelling parameters. The diffusion coefficients (D c ) of PAM hydrogel is 10 times higher than the literature value. 0.8% MWCNTs reinforced PAM hydrogel has excellent τc and electrical conductivity (0.76 mS/cm) with improvements in all properties. Lower D c of 0.8% MWCNTs/PAM hydrogel reveal that extent of crosslinking is much important than density of the system for a better collective diffusion of the respective solvent. 相似文献