( 摘 要:星型結(jié)構(gòu)相比較于線型結(jié)構(gòu)具有更穩(wěn)定的形態(tài)和更優(yōu)異的力學(xué)性能。選用季戊四醇(PET)為引發(fā)劑,辛酸亞錫(Sn(Oct)2)為催化劑,通過L-丙交酯(L-LA)的開環(huán)聚合(ROP)制備星型端羥基聚(L-丙交酯)(s-PLLA),并與聚乙二醇(PEG,相對(duì)分子質(zhì)量為1000)縮合制備四臂星型聚(L-丙交酯)-聚乙二醇共聚物(s-PLLA-PEG)。采用1H-核磁共振、13C-核磁共振、傅里葉變換紅外光譜、超高效聚合物色譜儀對(duì)產(chǎn)物進(jìn)行表征,并用靜電紡絲技術(shù)制備s-PLLA-PEG纖維膜進(jìn)行親水性能測(cè)試。結(jié)果表明:s-PLLA-PEG共聚物被成功合成;相對(duì)于s-PLLA,s-PLLA-PEG的熔體溫度和玻璃化轉(zhuǎn)變溫度降低,柔韌性得到改善,韌性增強(qiáng);s-PLLA-PEG纖維膜對(duì)水的接觸角是84.10°,隨著時(shí)間的推移,接觸角逐漸減小,最終水被纖維膜完全吸收,相比較s-PLLA纖維膜具有更強(qiáng)的親水性。該研究表明,PEG嵌段的引入可以有效改善s-PLLA纖維膜的親水性,展現(xiàn)出靜電紡s-PLLA-PEG纖維膜在醫(yī)用敷料領(lǐng)域的應(yīng)用前景。
關(guān)鍵詞:星型;聚(L-丙交酯)-聚乙二醇共聚物;靜電紡絲;親水性
中圖分類號(hào):O631.5
文獻(xiàn)標(biāo)志碼:A
文章編號(hào):1009-265X(2024)03-0045-08
收稿日期:20230802
網(wǎng)絡(luò)出版日期:20231102
基金項(xiàng)目:浙江省重點(diǎn)研發(fā)項(xiàng)目(2023C01095)
作者簡(jiǎn)介:邢東風(fēng)(1998-),女,安徽蕪湖人,碩士研究生,主要從事功能材料方面的研究。
通信作者:金達(dá)萊,E-mail:jdl_zist@126.com
聚乳酸(PLA)是一種具有生物可降解性的高分子材料,在生物醫(yī)學(xué)領(lǐng)域有著廣泛的應(yīng)用,可以用于蛋白質(zhì)和多肽藥物的控制輸送,制造醫(yī)療器械和傷口敷料以及組織工程中的支架等[1-2]。PLA在自然界中可實(shí)現(xiàn)循環(huán)再生,其最終分解產(chǎn)物為CO2和H2O[3]。然而,PLA的疏水性強(qiáng),韌性低,在自然條件下降解速率緩慢,導(dǎo)致其應(yīng)用存在局限性。在親水性物質(zhì)中,聚乙二醇(PEG)因其無毒、親水和可生物降解等優(yōu)點(diǎn)[4-5],常被應(yīng)用于生物醫(yī)用領(lǐng)域。它能夠在人體內(nèi)溶于組織液中,促進(jìn)血液循環(huán),分子量4000以下的PEG能被機(jī)體迅速排除而不產(chǎn)生任何毒副作用[6-7]。以PEG對(duì)PLA進(jìn)行共聚改性,可有效改善PLA的加工性能和柔韌性能[8]。Zhao等[9]通過羧基化PLA的雙酰氯與單羥基或二羥基PEG進(jìn)行偶聯(lián)反應(yīng),合成了一系列高分子量的PLA和PEG三嵌段和多嵌段共聚物,并研究了嵌段比對(duì)共聚物的力學(xué)性能和降解性能的影響。Eldessouki等[10]采用多元醇引發(fā)劑,改變反應(yīng)濃度和反應(yīng)溫度,在溶液中生成四臂星型結(jié)構(gòu)PLA,并通過交聯(lián)來提高材料的機(jī)械性能。眾多研究表明,將PEG引入PLA共聚物中,能有效地增加PLA的鏈遷移率,改善其物理性能和親水性能,從而拓寬PLA的潛在應(yīng)用范圍。
Buwalda等[11]和Buwalda等[12]采用端胺或端羥基的八臂星型PEG與L-LA開環(huán)聚合,合成八臂PEG-PLLA星型嵌段共聚物,并溶解在適量水中得到水凝膠;研究發(fā)現(xiàn)立體絡(luò)合水凝膠具有更好的力學(xué)性能和更高的抗水解穩(wěn)定性。與相同分子量和組成的線性聚合物相比,特殊結(jié)構(gòu)的星型聚合物具有更小的流體力學(xué)體積和更低的黏度[13-14],并能表現(xiàn)出獨(dú)特的形態(tài)、熱性能和降解特征。但關(guān)于PLA-PEG嵌段共聚物的親水性能研究鮮見報(bào)道。
靜電紡絲是利用靜電為驅(qū)動(dòng)力,通過溶液法紡絲制備聚合物纖維,其纖維膜具有多孔結(jié)構(gòu)和超細(xì)的纖維形態(tài)[15-16]。Luu等[17]對(duì)PLA-PEG三嵌段共聚物進(jìn)行靜電紡絲,探索溶液組成對(duì)形態(tài)的影響,并摻雜質(zhì)粒DNA進(jìn)行細(xì)胞轉(zhuǎn)染性和生物活性研究;該結(jié)果表明,PEG的存在使PLA的結(jié)晶度增加,纖維網(wǎng)絡(luò)結(jié)構(gòu)形態(tài)更加完整。然而,目前關(guān)于PLA-PEG纖維膜的親水性能在學(xué)術(shù)界尚未深入研究。
本文通過L-LA的開環(huán)聚合制備星型的端羥基聚(L-丙交酯)(s-PLLA),再與PEG縮合得到四臂星型聚(L-丙交酯)-聚乙二醇共聚物(s-PLLA-PEG),并探究PEG的接枝對(duì)纖維膜的形貌、力學(xué)性能和水接觸角的影響。本文利用靜電紡絲技術(shù)制備s-PLLA-PEG星型共聚物纖維膜,提出一種新的嵌段結(jié)構(gòu)纖維膜的制備方法,并研究其親水性能,為s-PLLA-PEG纖維膜在醫(yī)用敷料方面的應(yīng)用提供研究參考。
1 實(shí)驗(yàn)部分
1.1 s-PLLA-PEG的制備
通過乙醇和乙酸乙酯重結(jié)晶提純[18]的L-丙交酯(L-LA,上海麥克林生化科技有限公司),與引發(fā)劑季戊四醇(PET,上海凌峰化學(xué)試劑有限公司)以及催化劑辛酸亞錫(Sn(Oct)2,上海麥克林生化科技有限公司)反應(yīng)[19],得到白色固體s-PLLA。將s-PLLA"和過量的丁二酸酐(SA,上海麥克林生化科技有限公司)反應(yīng)[9],合成末端羧基化的白色固體s-PLLA-COOH,并與聚乙二醇(PEG,相對(duì)分子質(zhì)量為1000,上海麥克林生化科技有限公司)溶于三氯甲烷(CHCl3,AR,99%,國藥集團(tuán)化學(xué)試劑有限公司),加入催化劑4-二甲氨基吡啶(DMAP,上海麥克林生化科技有限公司)和二環(huán)己基碳二亞胺(DCC,上海麥克林生化科技有限公司)反應(yīng)[1],通過抽濾去除反應(yīng)生成的二環(huán)己基脲白色沉淀(DCU),加入無水乙醇攪拌至完全沉淀,60 ℃干燥,得到白色s-PLLA-PEG多嵌段共聚物。
s-PLLA-PEG的具體合成過程[8,19]如圖1所示。
1.2 s-PLLA-PEG纖維膜的制備
將s-PLLA-PEG多嵌段共聚物溶解在適量的二氯甲烷中,攪拌均勻得到紡絲液。將配置好的紡絲液置于10 mL的一次性注射器內(nèi),注射針頭內(nèi)徑為1.2 mm。紡絲流速設(shè)置為2 mLh,轉(zhuǎn)速為100 rmin,正負(fù)電壓分別為20 kV和-5 kV。
2 測(cè)試與表征
采用Nicilet is20型傅里葉紅外光譜儀對(duì)共聚產(chǎn)物進(jìn)行定性分析,制樣方法為KBr壓片法。采用Bruker400型核磁共振波譜研究共聚產(chǎn)物的化學(xué)結(jié)構(gòu),溶劑為CDCl3,四甲基硅烷為內(nèi)標(biāo)。采用Waters ACQUIT型超高效聚合物色譜儀測(cè)定共聚產(chǎn)物的分子量及其分布,溶劑為四氫呋喃,標(biāo)樣為聚苯乙烯,柱溫為45 ℃。采用中旺ISV400-2型自動(dòng)黏度檢測(cè)儀測(cè)定共聚產(chǎn)物的黏度,溶劑為四氯乙烷和苯酚混合溶液。
通過METTLERDSC3型差示掃描量熱儀研究共聚產(chǎn)物的熱行為,在氮?dú)鈿夥障聦?duì)樣品進(jìn)行熱分析。首先將樣品加熱到180 ℃,再冷卻到20 ℃,以消除熱歷史。在第一次掃描后,樣品以10 ℃min的速度再次加熱。采用TG209型熱重分析儀研究共聚產(chǎn)物的熱穩(wěn)定性,樣品在氮?dú)鈿夥障乱?10 ℃min"的升溫速率從室溫加熱到600 ℃。使用Sigma500型場(chǎng)發(fā)射掃描電子顯微鏡觀察纖維膜的表面微觀形貌。通過KRUSS DSA25S型接觸角儀測(cè)量纖維膜與水的接觸角度。將2 μL蒸餾水在室溫下滴定在膜片上,觀察膜片表面情況。采用68TM-30型電子萬能材料試驗(yàn)機(jī)對(duì)纖維膜進(jìn)行力學(xué)性能測(cè)試。試樣規(guī)格為0.5 cm×2.0 cm的長方形,拉伸速率為0.5 mmmin。
3 結(jié)果與討論
3.1 結(jié)構(gòu)表征
圖2為s-PLLA、s-PLLA-COOH、s-PLLA-PEG和PEG的紅外光譜圖。圖2中1775 cm-1處的吸收峰歸屬于CO伸縮振動(dòng),1170 cm-1處的吸收峰歸屬于CO伸縮振動(dòng),表明酯基的形成[20]。s-PLLA-PEG在2998、2946 cm-1和2884 cm-1處分別有3個(gè)CH伸縮振動(dòng)特征峰,這表明CH3、CH和CH2基團(tuán)的存在[21],證實(shí)形成了PLLA-PEG多嵌段共聚物。
圖3(a)為s-PLLA、s-PLLA-COOH和s-PLLA-PEG的1H-NMR譜圖。季戊四醇上歸屬為CH2和OH的特征峰,分別出現(xiàn)在化學(xué)位移"δ=4.68和δ=3.48處。反應(yīng)后,化學(xué)位移δ=3.48處的峰消失,化學(xué)位移δ=4.68處的峰偏移到δ=417處,歸因?yàn)镃H2與L-LA的COO接合使CH2的化學(xué)位移發(fā)生偏移,說明季戊四醇全部參與反應(yīng)。圖3中化學(xué)位移δ=5.20和δ=1.55處的峰分別歸屬為PLLA嵌段的CH和CH3[22],說明L-LA發(fā)生開環(huán)聚合?;瘜W(xué)位移δ=3.65處的峰歸屬為PEG的CH[19]2,說明存在PEG鏈段。
通過每個(gè)單體組成的1H-NMR信號(hào)積分來估算嵌段共聚物的分子量,計(jì)算公式[2,22]如下:
Mw = 4(2A2 A1+1)×72+136
其中:A1表示來自PET引發(fā)劑的CH2的峰面積(見圖3(a));
A2表示與酯基相連的CH的峰面積(見圖3(a));72表示PET的分子量;136表示PLLA重復(fù)單元的分子量。分子量結(jié)果如表1所示。
圖3(b)為s-PLLA、s-PLLA-COOH和s-PLLA-PEG的13C-NMR譜圖。圖4中化學(xué)位移δ=62和"δ=40處的峰分別歸屬為季戊四醇的CH2基團(tuán)和中心C原子[24],證實(shí)星型PLLA結(jié)構(gòu)的存在[1]。
圖4為s-PLLA、s-PLLA-COOH和s-PLLA-PEG的APC曲線,分子量結(jié)果見表1。產(chǎn)物的分子量分布較窄且均為單峰結(jié)構(gòu),說明s-PLLA與PEG發(fā)生了酯化反應(yīng)。與s-PLLA的APC曲線相比,s-PLLA-PEG的分子量分布曲線出現(xiàn)左移,即s-PLLA-PEG的分子量明顯較高,表示所得產(chǎn)物的分子量隨著聚合反應(yīng)的持續(xù)進(jìn)行而逐步增大。
3.2 s-PLLA-PEG嵌段共聚物的熱穩(wěn)定性
圖5(a)為s-PLLA-PEG的TG和DTG曲線,可見s-PLLA-PEG從175 ℃開始降解。共聚物表現(xiàn)出兩次質(zhì)量損失,第一次失重發(fā)生在175~358 ℃,失重率為68%,與PLLA的理論含量(質(zhì)量分?jǐn)?shù)為72%)近似,可以歸屬為PLLA嵌段的降解;第二次失重發(fā)生在358~422 ℃,共聚物完全分解,失重率為28%,與PEG嵌段的理論含量(質(zhì)量分?jǐn)?shù)為28%)一致。
圖5(b)為s-PLLA和s-PLLA-PEG的DSC曲線。s-PLLA的玻璃化轉(zhuǎn)變溫度(Tg)在33.62~6031 ℃之間,與報(bào)道的50~60 ℃范圍一致[10,24];當(dāng)單體與引發(fā)劑的摩爾比增加,Tg沒有出現(xiàn)與文獻(xiàn)一致的變化趨勢(shì),因?yàn)門g主要取決于聚合物鏈段分子間和分子內(nèi)的作用力,也取決于分子量。s-PLLA的熔融溫度是144.67 ℃,與Eldessouki等[10]報(bào)道的一致,熔融溫度主要隨分子結(jié)構(gòu)和組成變化。大多數(shù)PLLA顯示出雙峰熔融峰,是因?yàn)镻LLA在熔融過程中發(fā)生不完全結(jié)晶和再結(jié)晶現(xiàn)象[24]。
s-PLLA-PEG的Tg在6.24~19.35 ℃之間,遠(yuǎn)低于s-PLLA的Tg,表明分子鏈柔性變大,共聚物韌性增強(qiáng)。在兩次熱循環(huán)中都沒有觀察到冷晶化和熔融峰,因此無法確認(rèn)熔融溫度和結(jié)晶溫度。DSC曲線上沒有發(fā)現(xiàn)放熱峰,說明s-PLLA-PEG是無定形的,即為非晶態(tài)。
3.3 s-PLLA-PEG纖維膜的表面形貌
圖6為s-PLLA和s-PLLA-PEG纖維膜的掃描電鏡圖及直徑分布圖。從圖6中可以觀察到,纖維膜由相互交叉的纖維形成網(wǎng)狀結(jié)構(gòu),纖維粗細(xì)不均。純s-PLLA纖維膜的纖維較粗,直徑為1.29~2.33 μm,均勻性較差。 s-PLLA-PEG纖維膜的纖維直徑顯著降低,為0.79~1.02 μm,且纖維粗細(xì)較均勻,紡絲效果較好。
3.4 s-PLLA-PEG纖維膜的力學(xué)性能
PLLA脆性較大[25],純s-PLLA纖維膜無法從襯底上完整取下。本文僅對(duì)s-PLLA-PEG纖維膜進(jìn)行拉伸測(cè)試,結(jié)果如圖7所示。柔性鏈段PEG接枝到s-PLLA上,分子鏈柔性增大,使s-PLLA-PEG纖維膜變軟,具有一定的韌性,3次拉伸測(cè)試的平均拉伸強(qiáng)度為0.34 MPa。
3.5 s-PLLA-PEG纖維膜的親水性能
圖8為s-PLLA纖維膜和s-PLLA-PEG纖維膜的親水性能測(cè)試結(jié)果。如圖8(a)—(c)所示,s-PLLA"纖維膜與水的接觸角為132.10°,是明顯的疏水性物質(zhì)。測(cè)出的接觸角比Yu等[26]報(bào)道的稍大,這種現(xiàn)象的出現(xiàn)可能是由于共聚物具有星型的特殊結(jié)構(gòu),使纖維之間連接更緊密,疏水性更強(qiáng)。PEG接枝后,s-PLLA-PEG與水的接觸角有不同程度的減小(如圖8(d)—(f)所示),和文獻(xiàn)[26]中描述的現(xiàn)象相一致,與文獻(xiàn)[26]采用相容方式制備纖維膜不同,本文通過聚合方式,得到的纖維膜親水性更強(qiáng),并隨著時(shí)間的推移,接觸角不斷減小,直至水完全滲透到纖維膜里。親水性的提高可以歸因于PEG嵌段的引入,通過氫鍵與水的相互作用,改善膜與水之間的潤濕性。tular等[20]測(cè)得PLAPNCS樣品與水的接觸角從初始的118°緩慢下降到81°,親水疏水行為的變化非常緩慢。本研究得到的"s-PLLA-PEG"纖維膜與水的接觸角,在40 s內(nèi)從8410°下降到19.20°(見圖8(g)),親水效果更加明顯。s-PLLA-PEG纖維膜良好的親水性能可以作為醫(yī)用敷料來保護(hù)受損皮膚,防止創(chuàng)面感染和嚴(yán)重脫水,提供有利于傷口愈合的濕潤環(huán)境。
4 結(jié) 論
本文以L-丙交酯、季戊四醇和聚乙二醇(相對(duì)分子質(zhì)量為1000)為原料,制備出四臂星型聚(L-丙交酯)-聚乙二醇共聚物,采用1H-核磁共振、13C-核磁共振、傅里葉變換紅外光譜、超高效聚合物色譜儀等方法證實(shí)s-PLLA-PEG共聚物的合成。通過靜電紡絲技術(shù)創(chuàng)新地制備出s-PLLA-PEG纖維膜,并對(duì)纖維膜的表面形貌、力學(xué)性能和親水性能進(jìn)行測(cè)試和分析。研究結(jié)果表明:s-PLLA-PEG纖維膜的纖維粗細(xì)較為均勻,直徑為0.79~1.02 μm;s-PLLA-PEG"纖維膜的平均拉伸強(qiáng)度為0.34 MPa;PEG嵌段的引入可以有效改善s-PLLA纖維膜表面的親疏水性,使其從疏水性物質(zhì)變?yōu)橛H水性物質(zhì),水接觸角為84.10°。s-PLLA-PEG纖維膜新穎的制備方式及其良好的親水性能為纖維膜材料的開發(fā)和應(yīng)用提供一種研究思路,該材料在醫(yī)用敷料領(lǐng)域具有應(yīng)用前景。
參考文獻(xiàn):
[1]"LIN Y, ZHANG A. Synthesis and characterization of star-shaped poly(D,L-lactide)-block-poly(ethylene glycol) copolymers[J]. Polymer Bulletin, 2010, 65(9): 883-892.
[2]"MDOBAIDUR R,朱斐超,楊瀟東,等.熱塑性聚氨酯增韌聚乳酸及其熔噴非織造材料研究[J].絲綢,2021,58(10):28-35.
MDOBAIDUR R, ZHU Feichao, YANG Xiaodong, et al. Study on toughened polylactic acid and its meltblown nonwovens by thermoplastic polyurethane[J]. Journal of Silk, 2021, 58(10):28-35.
[3]"AL-LAMI H, AL-MAYAHI B, HADDAD A. Synthesis of some nano multi arms polylactide-dipentaerythritol organic polymers[J]. Journal of the Mexican Chemical Society, 2020, 64(4): 253-63.
[4]"BASU A, KUNDURU K R, DOPPALAPUDI S, et al. Poly(lactic acid) based hydrogels[J]. Advanced Drug Delivery Reviews, 2016, 107: 192-205.
[5]"ZHANG Z, ZHANG Y, SONG S, et al. Recent advances in the bioanalytical methods of polyethylene glycols and PEGylated pharmaceuticals[J]. Journal of Separation Science, 2020, 43(910): 1978-1997.
[6]"SHI J, YU L, DING J. PEG-based thermosensitive and biodegradable hydrogels[J]. Acta Biomaterialia, 2021, 128: 42-59.
[7]"劉愛學(xué),鄭梯和,譚玉寶,等.三臂聚乳酸對(duì)線型聚乳酸性能的影響[J].塑料工業(yè),2016,44(11):132-137.
LIU Aixue, ZHENG Tihe, TAN Yubao, et al.Influence of three-armed PLLA on properties of linear PLLA[J]. Plastic Industry, 2016, 44 (11): 132-137.
[8]"LEE S J, HAN B R, PARK S Y, et al. Sol-gel transition behavior of biodegradable three-arm and four-arm star-shaped PLGA-PEG block copolymer aqueous solution[J]. Journal of Polymer Science Part A: Polymer Chemistry, 2006, 44(2): 888-899.
[9]"ZHAO H S, LIU Z, PARK S H, et al. Preparation and characterization of PEGPLA multiblock and triblock copolymer[J]. Bulletin of the Korean Chemical Society, 2012, 33(5): 1638-1642.
[10]"ELDESSOUKI M, BUSCHLE-DILLER G, GOWAYED Y. Solution-based synthesis of a four-arm star-shaped poly(L-lactide)[J]. Designed Monomers and Polymers, 2016, 19(2): 180-192.
[11]"BUWALDA S J, DIJKSTRA P J, CALUCCI L, et al. Influence of amide versus ester linkages on the properties of eight-armed PEG-PLA star block copolymer hydrogels[J]. Biomacromolecules, 2010, 11(1): 224-232.
[12]"BUWALDA S J, CALUCCI L, FORTE C, et al. Stereo complexed 8-armed poly(ethylene glycol)-poly(lactide) star block copolymer hydrogels: Gelation mechanism, mechanical properties and degradation behavior[J]. Polymer, 2012, 53(14): 2809-2817.
[13]"張安強(qiáng),林雅鈴,魏芬芬,等.星形聚乙二醇-聚乳酸嵌段共聚物的合成與表征[J].高分子材料科學(xué)與工程,2011,27(11):84-88.
ZHANG Anqiang, LIN Yaling, WEI Fenfen, et al.Synthesis and characterization of multi-arm star-shaped poly (ethylene glycol)-b-poly (L-lactide) copolymer prepared by ring-opening polymerization[J]. Polymer Materials Science amp; Engineering, 2011, 27(11): 84-88.
[14]"GROTHE T, WEHLAGE D, BHM T, et al. Needleless electrospinning of PAN nanofibre mats[J]. Tekstilec, 2017, 60(4): 290-295.
[15]"蘇芳芳,經(jīng)淵,宋立新,等.我國靜電紡絲領(lǐng)域研究現(xiàn)狀及其熱點(diǎn):基于CNKI數(shù)據(jù)庫的可視化文獻(xiàn)計(jì)量分析[J].東華大學(xué)學(xué)報(bào)(自然科學(xué)版),2024,50(1):45-54.
SU Fangfang,JING Yuan, SONG Lixin, et al. Present situation and hotspot of electrospinning in China: Visual bibliometric analysis based on CNKI database[J]. Journal of Donghua University (Natural Science),2024,50(1):45-54.
[16]"LO J S C, DAOUD W, TSO C Y, et al. Optimization of polylactic acid-based medical textiles via electrospinning for healthcare apparel and personal protective equipment[J]. Sustainable Chemistry and Pharmacy, 2022, 30: 100891.
[17]"LUU Y K, KIM K, HSIAO B S, et al. Development of a nanostructured DNA delivery scaffold via electrospinning of PLGA and PLA-PEG block copolymers[J]. Journal of Controlled Release, 2003, 89(2): 341-353.
[18]"李霞,劉晨光,賀愛華.L-丙交酯的純化研究[J].青島科技大學(xué)學(xué)報(bào)(自然科學(xué)版),2011,32(5):509-513.
LI Xia, LIU Chenguang, HE Aihua.Study on purification of L-lactide[J]. Journal of Qingdao University of Science and Technology (Natural Science Edition), 2011, 32(5): 509-513.
[19]"YUN Y J, PARK K M, JOUNG Y K, et al. In situ gel forming stereo complex composed of four-arm PEG-PDLA and PEG-PLLA block copolymers[J]. Macromolecular Research, 2008, 16(8): 704-710.
[20]"WANG M, ZHAN J, XU L, et al. Synthesis and charac-terization of PLGA-PEG-PLGA based thermosensitive polyurethane micelles for potential drug delivery[J]. Journal of Biomaterials Science Polymer Edition, 2021, 32(5): 613-634.
[21]"李亮,裴斐斐,劉淑萍,等.聚乳酸納米纖維基載藥敷料的制備與表征[J].紡織學(xué)報(bào),2022,43(11):1-8.
LI Liang, PEI Feifei, LIU Shuping, et al. Preparation and characterization of polylactic acid nanofiber based drug loaded dressings[J].Journal of Textile Research, 2022, 43 (11): 1-8.
[22]"YU S, ZHANG Y, HU H, et al. Effect of maleic anhydride grafted poly(lactic acid) on rheological behaviors and mechanical performance of poly(lactic acid)poly(ethylene glycol) (PLAPEG) blends[J]. RSC Advances, 2022, 12(49): 31629-31638.
[23]"WANG L Y, JING X, CHENG H B, et al. Rheology and crystallization of long-chain branched poly(L-lactide)s with controlled branch length[J]. Industrial amp; Engineering Chemistry Research, 2012, 51(33): 10731-10741.
[24]"YUAN M, HE Z, LI H, et al. Synthesis and characteri-zation of star polylactide by ring-opening polymerization of l-lactic acid O-carboxyanhydride[J]. Polymer Bulletin, 2014, 71(6): 1331-1347.
[25]"張礦生,唐梅榮,薛小佳,等.聚乳酸-聚乙二醇共混物的結(jié)晶與降解行為[J].化工學(xué)報(bào),2021,72(2):1181-1190.
ZHANG Kuangsheng, TANG Meirong, XUE Xiaojia, et al. Crystallization and degradation behavior of poly (lactic acid)poly (ethylene glycol) blends[J]. CIESC Journal, 2021, 72(2): 1181-1190.
[26]"YU H Y, WANG C, ABDALKARIM S Y H. Cellulose nanocrystalspolyethylene glycol as bifunctional reinforcingcompatibilizing agents in poly(lactic acid) nanofibers for controlling long-term in vitro drug release[J]. Cellulose, 2017, 24(10): 4461-4477.
[27]"胡丹丹,章偉華,劉琳,等.聚氨酯絲膠蛋白復(fù)合膜的制備及其性能研究[J].浙江理工大學(xué)學(xué)報(bào)(自然科學(xué)版),2012,29(4):469-473.
HU Dandan, ZHANG Weihua, LIU Lin, et al. Fabrication and characterization of polyurethanesericin composite membranes[J]. Journal of Zhejiang University of Science and Technology (Natural Sciences), 2012, 29(4): 469-473.
[28]"ZHANG C, YANG X, HU W, et al. Preparation and characterization of carboxymethyl chitosancollagen peptideoxidized konjac composite hydrogel[J]. International Journal of Biological Macromolecules, 2020, 149: 31-40.
Preparation and hydrophilic properties of star-shaped PLLA-PEG block copolymer fiber membranes
XING Dongfeng1, LI Yunhuan1, GAO Yu1, WANG Fuxing1, FU Qiang2, JIN Dalai1
(1.School of Materials Science amp; Engineering, Zhejiang Sci-Tech University, Hangzhou 310018, China;
2.Bizheng Pharmaceutical Technology (Zhejiang) Co., Ltd., Hangzhou 313201, China)
Abstract:
Polylactic acid (PLA) is an important biodegradable polyester material with good biocompatibility, low toxicity, and good mechanical properties. Its main raw material is starch fermentation in plants, which is renewable and can be degraded by microorganisms (bacteria, fungi, etc.) in nature. As a raw material for plant photosynthesis, PLA enters the natural cycle. There is great potential for application in fields such as green plastics, tissue scaffolds, and biomedicine. However, PLA has poor hydrophilicity and a long degradation cycle, which limits its application in many aspects. So pure PLA materials can no longer meet the growing demand, and modifying them has become a trend.
The chemical modification of PLA mainly involves copolymerization with biodegradable substances to form linear or star-shaped copolymers. Research has found that compared to linear copolymers, star-shaped copolymers have smaller fluid mechanical volume and"lower viscosity, indicating better thermal and degradation performance. In addition, plasticizer modification can be targeted at the performance modification of polymers to expand their application fields. Generally, it will choose to copolymerize with hydrophilic substances, such as the commonly used polyethylene glycol (PEG), which can be dissolved in interstitial fluid in the human body, and PEG with molecular weight below 4,000 can be quickly eliminated from the body without any toxic and side effects."The addition of PEG can effectively increase the chain mobility of PLA, improve its ductility and stretchability, and thus broaden the potential application range of PLA.
To study the preparation process and hydrophilicity of star-shaped PLA multi block polymers, pentaerythritol (PET) was used as the initiator and stannous octanoate (Sn(Oct)2) as the catalyst. Star-shaped hydroxyl terminated poly (L-lactide) (s-PLLA) was prepared through ring opening polymerization (ROP), and condensed with polyethylene glycol (PEG, relative molecular weight is 1,000) to obtain four arm star-shaped poly (L-lactide) acid polyethylene glycol copolymers (s-PLLA-PEG). The s-PLLA-PEG fiber membrane was successfully prepared by electrospinning, and its surface morphology and hydrophilicity were tested and analyzed. A series of characterization methods were used to confirm the effective synthesis of polymers such as s-PLLA and s-PLLA-PEG. There are currently few reports on the research of PLA-modified fiber membranes. The results show that the melt temperature and glass transition temperature of s-PLLA-PEG decrease, and the flexibility is improved; the contact angle between s-PLLA fiber membrane and water is 132.10°, while the contact angle between the s-PLLA-PEG fiber membrane and water is 84.10°. Over time, the contact angle gradually decreases, and ultimately water is completely absorbed by the fiber membrane, exhibiting stronger hydrophilicity. Research has shown that when PEG is successfully grafted onto s-PLLA, the hydrophilicity of s-PLLA-PEG fiber membranes is significantly better than that of s-PLLA fiber membranes. This indicates that the presence of PEG can effectively improve the hydrophilicity and hydrophobicity of the surface of the s-PLLA fiber membrane, transforming it from a hydrophobic substance to a hydrophilic substance. Due to the excellent hydrophilicity of the s-PLLA-PEG fiber membrane, it has shown certain application prospects in medical dressings.
Keywords:
star-shaped; poly (L-lactide)-polyethylene glycol copolymer; electrospinning; hydrophilicity