雷射固化光聚合高分子之動力學研究

Kinetics of Photopolymerization for Laser Cured Resins

程奎達(Kuei-Ta Cheng)

指導教授 ： 黃鼎偉

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.03284

摘要

在了解光照厚層光敏感樹脂高分子聚合反應的動力方程式後，發現高分子聚合速率是光照強度、光起始劑濃度和吸收率的函式，光照強度分佈對樹脂固化的形狀影響很大，本篇論文我們利用解數個動力學耦合方程式來模擬高分子材料固化的過程，光照材料固化隨時間空間變化的情況都可以模擬出來；以往牙齒修復使用的光源接近發散的平面光束，光入射光敏感樹脂時受到表面或淺層材料吸收，使光照強度在進入深層或底層材料已大幅衰減，造成表面或淺層材料固化反應較劇烈，深層或底層材料固化反應較緩慢，光敏感樹脂表面與底層固化不均勻的現象，我們利用聚焦高斯光束來彌補光照強度被表面或淺層材料吸收所造成的衰減，設計在光照圓柱中心處表面初始光照強度與底層初始光照強度相同，在適當選取高斯光束的參數，像是光照強度、光束腰寬、波前曲率半徑等，可以使樹脂固化在深度方向較為均勻，而且只要知道單體分子固化門檻值(單體分子濃度降為初始濃度的多少百分比)、鏈聚合反應的傳播和終止反應常數，我們推導簡便的公式可以精確估算樹脂固化的時間；這些研究結果對於醫學及工業之厚層光照高分子固化應用有幫助。

關鍵字

光照高分子固化 ； 光敏感樹脂 ； 牙齒修復

並列摘要

The kinetics of photopolymerization of thick photosensitive resins illuminated by a focused Gaussian beam was studied theoretically. The polymerization rate is a function of the absorbance and concentration of the photoinitiator. Meanwhile, the light intensity distribution may also have strong effects on the shape of the polymerized resins. In this thesis, several kinetic coupling equations are solved to simulate the curing process of polymerization. The temporal and spatial photopolymerization process could be simulated quantitatively. In the past, the light source used in the dental restorations was close to the diverged plane wave. The incident light will be absorbed by surface or shallow materials, and light intensity in the deep materials attenuates rapidly. Therefore, we get an uneven polymerized resins which have non-ideal biological functions. We use a focused Gaussian beam to compensate for the light intensity attenuation caused by absorption of the surface or shallow materials, and we make the initial light intensity on the surface the same as the initial light intensity on the bottom. With a proper control of the characteristics of a focused Gaussian beam such as the light intensity, focusing distance, and beam waist, a nearly uniform polymerized resins can be achieved. As long as we know the polymerization threshold value (the concentration of monomers reduced to a specific percentage of the initial concentration), the propagation constant and the termination constant of radical chain polymerization, we could estimate quantitatively the completion time of polymerized resins by a simple equation. The theoretical results would be useful for designing the light sources for the medical and industrial applications using thick photopolymers.

並列關鍵字

photopolymerization ； laser cured resins ； dental restoration

參考文獻

[1] George Odian, Principles of polymerization, Fourth Edition, Wiley-Interscience, 2004.

[2] B. D. Fairbanks, M. P. Schwartz, C. N. Bowman, and K. S. Anseth, “Photoinitiated polymerization of PEG-diacrylate with lithium phenyl-2,4,6-trimethylbenzoylphosphinate: polymerization rate and cytocompatibility,” Biomaterials 30, 6702‒6707, 2009.

[4] G. Terrones and A. J. Pearlstein, “Effects of Optical Attenuation and Consumption of a Photobleaching Initiator on Local Initiation Rates in Photopolymerizations,” Macromolecules 34, 3195‒3204, 2001.

[5] G. Terrones and A. J. Pearlstein, “Effects of Kinetics and Optical Attenuation on the Completeness,Uniformity, and Dynamics of Monomer Conversion in Free-Radical

Photopolymerizations,” Macromolecules 34, 8894‒8906, 2001.