OBJECTIVE The aim of this study was to investigate the influence of the photoinitiator system on the polymerization kinetics of methacrylamide-based monomers as alternatives to methacrylates in adhesives dental-based materials. METHODS In total, 16 groups were tested. Monofunctional monomers (2-hydroxyethyl methacrylate) - HEMA; (2-hydroxy-1-ethyl methacrylate) -2EMATE, (2-hydroxyethyl methacrylamide) - HEMAM; and (N-(1-hydroxybutan-2-yl) methacrylamide) -2EM; were combined with bifunctional monomers containing the same polymerizing moieties as the monofunctional counterparts (HEMA-BDI; 2EMATE-BDI; HEMAM-BDI; and 2EM-BDI) at 50/50 M ratios. BHT was used as inhibitor (0.1 wt%) and the photoinitiators used were: CQ + EDMAB (0.2/0.8), BAPO (0.2), IVOCERIN (0.2), and DMPA (0.2), in wt%. The polymerization kinetics were monitored using Near-IR spectroscopy (∼6165 cm-1) in real-time while the specimens were photoactivated with a mercury arc lamp (Acticure 2; 320-500 nm, 300 mW/cm2) for 5 min, and maximum rate of polymerization (Rpmax, in %.s-̄1), degree of conversion at Rpmax (DC@Rpmax, in %), and the final degree of conversion (Final DC, in %) were calculated (n = 3). Initial viscosity was measured with an oscillating rheometer (n = 3). Data were analyzed using Two-way ANOVA for the polymerization kinetics and one-way ANOVA for the viscosity. Multiple comparisons were made using the Tukey's test (∝ = 0.05). RESULTS There was statistically significant interaction between monomer and photoinitiator (p < 0.001). For the methacrylates groups, the highest Rpmax was observed for HEMA + DMPA and 2EMATE + BAPO. For methacrylamides groups, the highest Rpmax were observed for HEMAM and 2EM, both with DMPA. Final DC was higher for the methacrylate groups, in comparison with methacrylamide groups, independent of the photoinitiators. However, for the methacrylamide groups, the association with BAPO led to the lowest values of DC. In terms of DC@Rpmax, methacrylate-based systems showed significantly higher values than methacrylamide formulations. DMPA and Ivocerin led to higher values than CQ/EDMAB and BAPO in methacrylamide-based compounds. BAPO systems showed de lowest values for both HEMA and HEMAM formulations. For the viscosity (Pa.s), only 2EM had higher values (1.60 ± 0.15) in comparison with all monomers. In conclusion, polymerization kinetics was affected by the photoinitiators for both monomers. Viscosity was significantly increased with the use of secondary methacrylamide. SIGNIFICANCE this work demonstrated the feasibility of using newly-synthesized methacrylamide monomers in conjunction with a series of initiator systems already used in commercial materials.

中文翻译：

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光引发剂体系对牙科粘合剂应用系统结构变化的仲甲基丙烯酰胺聚合的影响。

目的本研究的目的是研究光引发剂体系对甲基丙烯酸酰胺基单体（代替牙科用胶粘剂中的甲基丙烯酸酯）的聚合动力学的影响。方法总共测试了16组。单官能单体（甲基丙烯酸2-羟乙酯）-HEMA；（甲基丙烯酸2-羟基-1-乙酯）-2EMATE，（甲基丙烯酸2-羟乙基酯）-HEMAM; （N-（1-羟基丁烷-2-基）甲基丙烯酰胺）-2EM；以50 / 50M的比率将其与含有与单官能对应物相同的聚合部分（HEMA-BDI； 2EMATE-BDI； HEMAM-BDI；和2EM-BDI）的双官能单体组合。BHT用作抑制剂（0.1 wt％），使用的光引发剂为：CQ + EDMAB（0.2 / 0.8），BAPO（0.2），IVOCERIN（0.2）和DMPA（0.2），以wt％计。聚合动力学使用近红外光谱（〜6165 cm-1）进行实时监测，同时用汞弧光灯（Acticure 2; 320-500 nm，300 mW / cm2）对样品进行5分钟的光活化，并计算最大聚合速率（Rpmax，以％.s-̄1为单位），Rpmax处的转化度（DC @ Rpmax，以％为单位）和最终转化率（最终DC，以％为单位）（n = 3）。用振荡流变仪（n ＝ 3）测量初始粘度。使用双向ANOVA进行聚合动力学分析数据，使用单向ANOVA进行粘度分析数据。使用图基检验（∝ = 0.05）进行了多次比较。结果单体与光引发剂之间存在统计学上的显着相互作用（p <0.001）。对于甲基丙烯酸酯基团，对于HEMA + DMPA和2EMATE + BAPO，观察到最高的Rpmax。对于甲基丙烯酰胺基团，使用DMPA的HEMAM和2EM观察到最高的Rpmax。与甲基丙烯酰胺基团相比，独立于光引发剂的甲基丙烯酸酯基团的最终DC更高。但是，对于甲基丙烯酰胺基团，与BAPO的缔合导致DC的最小值。在DC @ Rpmax方面，基于甲基丙烯酸酯的体系显示出比甲基丙烯酰胺配方更高的值。在基于甲基丙烯酰胺的化合物中，DMPA和Ivocerin的值高于CQ / EDMAB和BAPO。BAPO系统显示HEMA和HEMAM配方的最低值。对于粘度（Pa.s），与所有单体相比，只有2EM具有更高的值（1.60±0.15）。总之，两种单体的光引发剂都会影响聚合动力学。使用仲甲基丙烯酰胺可显着提高粘度。意义这项工作证明了将新合成的甲基丙烯酰胺单体与商业材料中已使用的一系列引发剂体系结合使用的可行性。