纳米材料掺杂型聚乙烯醇双交联复合水凝胶的力-化学性质

Mechanical-Chemical Properties of Nanomaterial Doped Poly(vinyl alcohol) Dual Cross-linked Hydrogels

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。

In the present work,a series of graphene oxide(GO)/hydroxyapatite(HA)/poly(vinyl alcohol)(PVA)dual cross-linked composite hydrogels were synthesized by applying the combinatorial methods of chemical crosslinking and cyclic freezing-thawing,and varying the mass ra-tios of GO to PVA,HA to PVA and the number of times of cyclic freezing-thawing.Firstly,PVA chains covalently crosslinked at a rather low concentration(considering the bio-safety)of glutaraldehyde for the chemical-crosslinking of the first network.Then,during the cyclic freezing-thawing process,the PVA crystalline domains served as cross-linking knots and the hydrogen-bonding were formed for the secondary physical-crosslinking network.The resultant hydrogels were defined as the GO/HA/PVA dual cross-linked hydrogels.The structure of the GO/HA/PVA nanocomposite hydrogels was characterized by the high-resolution scanning electron microscope and X-ray diffraction.The tensile mechanical properties were further investigated for the dual cross-linked hydrogels differing in mass ratios of GO to PVA(0%-2.6%)and HA to PVA(0.22-1.10),and number of times of cyclic freezing-thawing(0,3,7).When the mass ratio of GO/PVA reached to 1.9%,HA/PVA reached to 0.66 and with 7 times cyclic freezing-thawing,the GO/HA/PVA dual cross-linked hydrogel achieved the maximum tensile strength and elongation at break of up to 695 kPa and 286%,and the Young s modulus was 78 kPa.We further investigated the water content and swelling behaviors of dual cross-linked hydrogels with various number of times of cyclic freezing-thawing(0,3,7).The results revealed that the water content was about 79.3%-81.7%,and the equilibrium swelling ratio was about 50.1%-72%.The hydrogel was expected to serve as cartilage substitution materials in clinical medicine field.