Structure architecture and property relation of hyperbranched polymer produced from triglyceride via RAFT polymerization

Hyperbranched polymer produced from triglycerides have been polymerized via reversible addition-fragmentation chain transfer polymerization (RAFT). Triglyceride is one of the main components in vegetable oils and has been considered stable, non-toxic and environmental friendly. Additionally, the unsaturation of fatty acid chains makes triglycerides competitive as monomer. Therefore, triglycerides are considered one of the most important bio-based chemical resources. The resulting hyperbranched polymers have great potential in coating, drug delivery, and etc.. Chemical modification has been applied to increase chemical activities of double bonds by introducing acrylate groups. Due to the high unsaturation of modified triglycerides ( ~ 2.6 functionality per molecule) , radical polymerization leads to macro-gelation at low conversion according to the classic Flory-Stockmayer theory. However, this work demonstrates that gelation process is easily affected or even avoid by simply tuning reaction conditions, which affect the competition of inter-/intra molecular reactions. The intra-molecular reactions decrease the efficiency of polymerization and lead the cyclings to form within macromolecules. The increased proportion of intra-molecular reactions not only suppresses the gelation process, but also leads to heterogeneity in structure. The less homogeneous structures deviate their chain relaxation dynamics from classic models. Zimm model and Rouse model have been successfully used to describe relaxation dynamics for hyperbranched polymers. Due to the high density of side chains, main chain entanglement is largely restricted. Furthermore, the side chains also interact with the main chains, may or may not providing drag or friction, leading the relaxation process obeying Zimm model or Rouse model. In this work, a close study of hyperbranched PAESO relaxation process has been done. Discussion about how branches and cyclings deviates the process from ideal Zimm model has given. Furthermore, in this work, a study of different triglyceride compositions has been done, i.e. what oleic/linoleic/linolenic fatty acids behave in reaction and affect physical properties. Lastly, preliminary data obtained from morphology study of hyperbranched PAESO has been displayed. Overall, this work connects the rheology properties with hyperbranched PAESO structures and synthesis conditions. It may provide insights in hyperbranched PAESO application

Gelation Suppression in RAFT Polymerization

In this article, we extend the understanding of gelation suppression in reversible addition–fragmentation chain-transfer (RAFT) polymerization in systems with long primary chains and high crosslinker content, regimes which have been mostly overlooked to date. Using a model methacrylate system, the gel point, apparent propagation rate constants, and polymer architectures are seen to vary in a systematic fashion. By combining our experimental data with several related studies, we introduce a new phenomenological parameter, the “crosslinking tendency,” that incorporates monomer concentration and excess functionality to universally describe the gelation suppression in both RAFT- and atom-transfer radical polymerization (ATRP)-controlled radical polymerization systems. The ability of the crosslinking tendency to quantitatively account for a broad range of RAFT and ATRP systems suggests that factors such as monomer architecture and details of activation/deactivation mechanisms may play only a secondary role in gel-point suppression

Multimodal evaluation of the bloodstream alteration before and after combined revascularization for Moyamoya disease

ObjectiveThis study aimed to explore the hemodynamic changes before and after anastomosis in patients with Moyamoya disease (MMD) using multiple models.MethodsWe prospectively enrolled 42 MMD patients who underwent combined revascularization. Intraoperative FLOW800 was performed before and after anastomosis, and parameters was collected, including maximum intensity, delay time, rise time, slope, blood flow index, and microvascular transit time (MVTT). Additionally, preoperative and postoperative hemodynamic parameters were measured using color Doppler ultrasonography (CDUS), including peak systolic velocity, end-diastolic velocity, resistance index (RI), pulsatility index (PI), and flow volume. Subsequently, the correlation between FLOW800 and CDUS parameters was explored.ResultsA total of 42 participants took part with an average age of 46.5 years, consisting of 19 men and 23 women. The analysis of FLOW800 indicated that both the delay time and rise time experienced a substantial decrease in both the recipient artery and vein. Additionally, the MVTT was found to be significantly reduced after the surgery (5.7 ± 2.2 s vs. 4.9 ± 1.6, p = 0.021). However, no statistically significant differences were observed among the other parameters. Similarly, all postoperative parameters in CDUS hemodynamics exhibited significant alterations in comparison to the preoperative values. The correlation analysis between FLOW800 and CDUS parameters indicated a significant association between MVTT and RI and PI, no significant relationships were found among the other parameters in the two groups.ConclusionThe hemodynamic outcomes of the donor and recipient arteries demonstrated significant changes following bypass surgery. The parameter of time appears to be more precise and sensitive in assessing hemodynamics using FLOW800. Multiple evaluations of hemodynamics could offer substantial evidence for perioperative management

Structure architecture and property relation of hyperbranched polymer produced from triglyceride via RAFT polymerization

Hyperbranched polymer produced from triglycerides have been polymerized via reversible addition-fragmentation chain transfer polymerization (RAFT). Triglyceride is one of the main components in vegetable oils and has been considered stable, non-toxic and environmental friendly. Additionally, the unsaturation of fatty acid chains makes triglycerides competitive as monomer. Therefore, triglycerides are considered one of the most important bio-based chemical resources. The resulting hyperbranched polymers have great potential in coating, drug delivery, and etc.. Chemical modification has been applied to increase chemical activities of double bonds by introducing acrylate groups. Due to the high unsaturation of modified triglycerides ( ~ 2.6 functionality per molecule) , radical polymerization leads to macro-gelation at low conversion according to the classic Flory-Stockmayer theory. However, this work demonstrates that gelation process is easily affected or even avoid by simply tuning reaction conditions, which affect the competition of inter-/intra molecular reactions. The intra-molecular reactions decrease the efficiency of polymerization and lead the cyclings to form within macromolecules. The increased proportion of intra-molecular reactions not only suppresses the gelation process, but also leads to heterogeneity in structure. The less homogeneous structures deviate their chain relaxation dynamics from classic models. Zimm model and Rouse model have been successfully used to describe relaxation dynamics for hyperbranched polymers. Due to the high density of side chains, main chain entanglement is largely restricted. Furthermore, the side chains also interact with the main chains, may or may not providing drag or friction, leading the relaxation process obeying Zimm model or Rouse model. In this work, a close study of hyperbranched PAESO relaxation process has been done. Discussion about how branches and cyclings deviates the process from ideal Zimm model has given. Furthermore, in this work, a study of different triglyceride compositions has been done, i.e. what oleic/linoleic/linolenic fatty acids behave in reaction and affect physical properties. Lastly, preliminary data obtained from morphology study of hyperbranched PAESO has been displayed. Overall, this work connects the rheology properties with hyperbranched PAESO structures and synthesis conditions. It may provide insights in hyperbranched PAESO application.</p

Gelation Suppression in RAFT Polymerization

In this article, we extend the understanding of gelation suppression in reversible addition–fragmentation chain-transfer (RAFT) polymerization in systems with long primary chains and high crosslinker content, regimes which have been mostly overlooked to date. Using a model methacrylate system, the gel point, apparent propagation rate constants, and polymer architectures are seen to vary in a systematic fashion. By combining our experimental data with several related studies, we introduce a new phenomenological parameter, the “crosslinking tendency,” that incorporates monomer concentration and excess functionality to universally describe the gelation suppression in both RAFT- and atom-transfer radical polymerization (ATRP)-controlled radical polymerization systems. The ability of the crosslinking tendency to quantitatively account for a broad range of RAFT and ATRP systems suggests that factors such as monomer architecture and details of activation/deactivation mechanisms may play only a secondary role in gel-point suppression.This document is the unedited Author’s version of a Submitted Work that was subsequently accepted for publication in Macromolecules, copyright © American Chemical Society after peer review. To access the final edited and published work see DOI: 10.1021/acs.macromol.9b00707. Posted with permission.</p

Table_1_Multimodal evaluation of the bloodstream alteration before and after combined revascularization for Moyamoya disease.DOCX

ObjectiveThis study aimed to explore the hemodynamic changes before and after anastomosis in patients with Moyamoya disease (MMD) using multiple models.MethodsWe prospectively enrolled 42 MMD patients who underwent combined revascularization. Intraoperative FLOW800 was performed before and after anastomosis, and parameters was collected, including maximum intensity, delay time, rise time, slope, blood flow index, and microvascular transit time (MVTT). Additionally, preoperative and postoperative hemodynamic parameters were measured using color Doppler ultrasonography (CDUS), including peak systolic velocity, end-diastolic velocity, resistance index (RI), pulsatility index (PI), and flow volume. Subsequently, the correlation between FLOW800 and CDUS parameters was explored.ResultsA total of 42 participants took part with an average age of 46.5 years, consisting of 19 men and 23 women. The analysis of FLOW800 indicated that both the delay time and rise time experienced a substantial decrease in both the recipient artery and vein. Additionally, the MVTT was found to be significantly reduced after the surgery (5.7 ± 2.2 s vs. 4.9 ± 1.6, p = 0.021). However, no statistically significant differences were observed among the other parameters. Similarly, all postoperative parameters in CDUS hemodynamics exhibited significant alterations in comparison to the preoperative values. The correlation analysis between FLOW800 and CDUS parameters indicated a significant association between MVTT and RI and PI, no significant relationships were found among the other parameters in the two groups.ConclusionThe hemodynamic outcomes of the donor and recipient arteries demonstrated significant changes following bypass surgery. The parameter of time appears to be more precise and sensitive in assessing hemodynamics using FLOW800. Multiple evaluations of hemodynamics could offer substantial evidence for perioperative management.</p