為了量測微奈米尺度的力學性質，現已廣泛應用奈米壓痕試驗機 ( Nanoindenter ) 以及原子力顯微鏡的奈米壓痕測試( AFM nanoindentation )來做奈米壓痕測試，而奈米壓痕測試也已經廣泛地應用在生物材料以及微生物等黏彈性試片的力學分析。然而在黏彈性材料的量測上，其黏彈性性質會使材料的應變須考慮時間因子，並且本實驗室在之前的研究發現，必須由量測到的Force-Distance curve的power law關係來選用接觸理論計算，若是不考慮power law關係，計算得到的楊氏模數值會隨著壓縮深度增加而呈指數下降，這並不符合楊氏模數是一固定值的材料本質特性[1]。
本實驗分別應用AFM以及Nanoindenter來對PMMA、PVA及PDMS三種黏彈性薄膜進行奈米壓痕量測分析。在AFM nanoindentation，我們以PeakForce QNM以及Force Volume兩種不同壓縮速率的力學測量模式來量測，分別為800 nm/s以及40 nm/s。由PMMA及PVA薄膜的實驗發現對於黏彈性材料而言，由於其應變並不是立即完全反應，而是需要一段時間來完全應變，因此以Force Volume mode來量測黏彈性材料比較精準，其壓縮速率使黏彈性薄膜有時間應變，並且使薄膜表面可以與探針貼合接觸，而得到真正探針在隨著壓縮深度改變該有的接觸面積，並且可以得到與文獻較符合的楊氏模數值，分別為PMMA = 4.50 GPa以及PVA為1.78 GPa。而PDMS的試驗，其Force–Distance Curve之power law在這兩種模式皆呈現1次方關係，因此在這兩種壓縮速度下皆無法使PDMS有時間完全應變。在此使用modified flat punch model來修正球型針的接觸半徑[1]，可以得到合理的楊氏模數。並可得到不同混和比例的PDMS之楊氏模數強弱差別，PDMS 5:1為11.90 MPa、PDMS 10:1為14.91MPa以及PDMS 15:1為6.20 MPa。
進一步，我們將Force Volume mode與Nanoindenter量測結果比較，在PMMA及PVA的部分，Force Volume mode以Sneddon model計算得到的楊氏模數值會小於Nanoindenter以Oliver & Pharr method計算的的楊氏模數值。我們發現這是因為PMMA及PVA薄膜在Force Volume mode也有塑性變形發生，因此需以Oliver & Pharr method計算楊氏模數會更精確得到PMMA = 5.50 GPa以及PVA = 3.07 GPa。
在不同比例的PDMS薄膜，其Force-Distance curve之power law由 Nanoindenter量測到的與AFM naonindentation量測的一樣呈現1次方關係，我們試用modified flat punch model計算Nanoindener量測的楊氏模數，分別為PDMS 5:1 = 106.61 MPa、PDMS 10:1 = 118.08 MPa以及PDMS 15:1 = 72.58 MPa，其趨勢雖然與AFM nanoindentaion相同，但數值卻大許多。因此我們再以compression test量測PDMS的楊氏模數，分別為PDMS 5:1 = 2.80 MPa、PDMS 10:1 = 3.13 MPa以及PDMS 15:1 = 1.35 MPa，其與AFM nanoindentation之結果是接近的，由此可知modified flat punch model適合修正AFM探針與PDMS薄膜之接觸半徑，然而對Nanoindenter的Berkovich探針的修正仍有限。
在非均質黏彈性薄膜，分別有PMMA / PDMS以及PDMS / PMMA兩種雙層膜。以Force Volume mode量測，原本的均質PMMA薄膜之power law為2次方關係。PMMA / PDMS雙層膜則是得到power law為1.5的Force–Distance curve，然而以Nanoindenter所量測的Force – Distance curve，其power law降低到了1次方。在PDMS / PMMA雙層膜部分，由Force – Distance curve來看，原本的均質材料PDMS其power law為1。而雙層膜材料PDMS / PMMA，以AFM nanoindentation以及Nanoindenter量測得到的power law也都仍為1次方。
因此我們推測PDMS對於兩種雙層膜的影響大於PMMA薄膜，所以在PMMA / PDMS雙層膜，隨著壓縮深度越深，底層PDMS的黏彈性性質影響越來越大，造成Force-Distance curve之power law由2次方降到1.5次方再降到1次方。而在PDMS / PMMA雙層膜，其壓縮深度由100 nm至2000 nm量測到的Force-Distance curve之power law則皆是1次方的關係。

In order to accurately measure the micro-nano mechanical properties of viscoelastic materials, we used two different modes that are PeakForce QNM and Force Volume for AFM nanoindentation and Nanoindenter to measure the modulus of PMMA, PVA and PDMS thin films. For PMMA and PVA thin films, compared to PeakForce QNM mode, we can get correct power law of Force-Distance curves which are consistent with tip geometry shape by Force Volume mode with slow indent rate. Since viscoelastic materials have enough time to do full deformation, the tip can contact the surface of sample completely. Otherwise, the Force-Distance curve display plastic deformation, so we use Oliver-Pharr method to calculate Elastic modulus that value is closed to measeured by Nanoindenter. And we calculate the modulus of PDMS thin film by modified flat-punch model since the power law of Force-Distance curve is 1 for both modes in AFM nanoindentation. For Nanoindenter, we suggested to use flat-punch probe to do the test.

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