Marcus Lin - Academia.edu (original) (raw)

Papers by Marcus Lin

arXiv (Cornell University), Nov 13, 2022

From hydrogels and plastics to liquid crystals, soft solids cover a wide array of synthetic and b... more From hydrogels and plastics to liquid crystals, soft solids cover a wide array of synthetic and biological materials 1 that play key enabling roles in advanced technologies such as 3D printing 2 , soft robotics 3 , wearable electronics 4 , self-assembly 5 , and bioartificial tissues 6, 7. Their elasticity and stimuli-induced changes in mechanical, optical, or electrical properties offer an unique advantage in designing and creating new dynamically functional components for sensing, micro-actuation, colour changes, information and mass transport. To harness the vast potential of soft solids through their ability to respond to the environment, a thorough understanding of their reactions when exposed to liquids is needed. Attempts to study the interactions between soft solids and liquids have largely focused on the wetting of soft solids 8-12 and its resulting deformation at equilibrium 12, 13 , in quasi-static state 14 , or in steady state 15, 16. Here we consider the frequently encountered case of unsteady wetting of a liquid on a soft solid, and show that transient deformation of the solid is necessary to understand unsteady wetting behaviours. We find that the initial spreading of the liquid occurs unin-1

A water droplet can bounce off superhydrophobic surfaces multiple times before coming to a stop. ... more A water droplet can bounce off superhydrophobic surfaces multiple times before coming to a stop. The energy loss for such droplet rebounds can be quantified by the ratio of the rebound speed UR and the initial impact speed UI , i.e., its restitution coefficient e = UR/UI . Despite much work in this area, there is still incomplete mechanistic explanation for the energy loss for rebounding droplets. Here, we measured e for sub-millimetric and millimetric sized droplets impacting two different superhydrophobic surfaces over a wide range of UI = 4–400 cm s−1. We proposed simple scaling laws to explain the observed non-monotonic dependence of e on UI . In the limit of low UI , energy loss is dominated by contact-line pinning and e is sensitive to the surface wetting properties, in particular to contact angle hysteresis Δcos θ of the surface. In contrast, in the limit of high UI , e is dominated by inertial-capillary effects and does not depend on Δcos θ.

Soft Matter

Viscous droplets impinging on soft substrates may exhibit several distinct behaviours including r... more Viscous droplets impinging on soft substrates may exhibit several distinct behaviours including repeated bouncing, wetting, and hovering, i.e., spreading and retracting after impact without bouncing back or wetting.

Facing shortages of personal protective equipment, some clinicians have advocated the use of barr... more Facing shortages of personal protective equipment, some clinicians have advocated the use of barrier enclosures (typically mounted over the head, with and without suction) to contain aerosol emissions from coronavirus disease 2019 (COVID-19) patients. There is however little evidence for its usefulness. To test the effectiveness of such a device, we built a manikin that can expire micron-sized aerosols at flow rates close to physiological conditions. We then placed the manikin inside the enclosure and used a laser sheet to visualize the aerosol leaking out. We show that with sufficient suction, it is possible to effectively contain aerosol from the manikin even at high flow rates (up to 60 L min−1) of oxygen, reducing aerosol exposure outside the enclosure by 99%. In contrast, a passive barrier without suction only reduces aerosol exposure by 60%.

IOP Conference Series: Materials Science and Engineering, 2017

A new multi-chamber rotary compressor (MCRC) has been designed and the simulation result is prese... more A new multi-chamber rotary compressor (MCRC) has been designed and the simulation result is presented in this paper. MCRC utilizes the space within the cylinder and it has the advantage of being more compact. Mathematical models which include geometrical, thermodynamics, mass flow and discharge valve have been formulated to evaluate the performance of MCRC. Parametric studies have also been carried out to determine the effects of design parameters such as suction and discharge ports size, valve length, valve thickness and valve width on compressor performance. In this paper, mathematical models will be presented and the predictions of the model will be shown and discussed.

IOP Conference Series: Materials Science and Engineering, 2017

A new multi-chamber rotary compressor (MCRC) is introduced in this paper. This new compressor is ... more A new multi-chamber rotary compressor (MCRC) is introduced in this paper. This new compressor is designed for compactness and energy efficient, with potential applications in refrigeration systems. In this paper, the design of the new compressor will be presented. Various components and their functions together with the overall advantages will be shown and discussed. In its basic form, it is a rotary compressor with two chambers working simultaneously to increase its output by maximizing the available working space and hence reduces material usage. The basic working principles will also be discussed and its advantages will be presented in comparison with other existing rotary compressors.

Polymer, 2005

Recent efforts to adapt nitroxide-mediated living radical polymerization chemistry to colloidal s... more Recent efforts to adapt nitroxide-mediated living radical polymerization chemistry to colloidal systems have shown considerable progress when miniemulsions are used. Miniemulsion SFRP in fact can yield higher conversions (O99%) and faster reaction rates than bulk SFRP. Much of the advantage of operating in miniemulsion arises from the inherent advantages of having a two phase system, in which the aqueous phase can be employed as a medium to introduce rate enhancing additives such as ascorbic acid to the reaction loci with a high degree of control. Additives such as ascorbic acid act by consuming excess nitroxide, and therefore directly influence the rate. Results on the effect of ascorbic addition on rate, molecular weight and livingness are presented. We have also begun to address the issue of high operating temperatures in TEMPO-mediated SFRP (w120-135 8C) that require a pressurized reactor. We have run experiments using TEMPO at 100 8C with slowly decomposing initiator added to maintain an appropriate free nitroxide concentration. Reasonable reaction rates are obtained, albeit with higher polydispersities (w1.6). Challenges and opportunities related to lower temperature operation are discussed.

Macromolecular Symposia, 2004

Nitroxide‐mediated living radical polymerizations of styrene were run in miniemulsion. Using a mo... more Nitroxide‐mediated living radical polymerizations of styrene were run in miniemulsion. Using a modified miniemulsion process that does not require the use of a volatile costabilizer, near complete conversions could be achieved in 2‐3 hours while preserving narrow molecular weight distributions and a high degree of chain livingness. Increased rates and final conversions were achieved by semi‐batch addition of the nitroxide scavenger ascorbic acid.

Journal of Polymer Science Part A: Polymer Chemistry, 2002

The rate‐accelerating effects of camphorsulfonic acid (CSA) on nitroxide‐mediated styrene miniemu... more The rate‐accelerating effects of camphorsulfonic acid (CSA) on nitroxide‐mediated styrene miniemulsion polymerization were studied. Polymerizations were initiated with benzoyl peroxide (BPO) as an initiator and mediated with either 2,2,6,6‐tetramethylpiperidinyloxy (TEMPO) or 4‐hydroxy‐2,2,6,6‐tetramethylpiperidinyloxy (OH‐TEMPO). Although CSA has been used to accelerate the rate in bulk nitroxide‐mediated polymerizations, it has not been well studied in emulsion/miniemulsion. With dispersed systems, the effectiveness of CSA is likely to be affected by partitioning between the aqueous and organic phases. In styrene miniemulsion experiments performed over a range of conditions, the effect of adding CSA varied from negligible to significantly increasing the final conversion and molecular weight, depending on the nitroxide:BPO ratio. At a ratio of nitroxide:BPO = 1.7, the effect of CSA addition is small, whereas the final conversion and molecular weight are dramatically enhanced by CSA...

Journal of Polymer Science Part A: Polymer Chemistry, 2006

Skip to Main Content. Wiley Online Library will be disrupted 3 Sep from 10-12 BST for monthly mai... more Skip to Main Content. Wiley Online Library will be disrupted 3 Sep from 10-12 BST for monthly maintenance. ...

Chemical Engineering Science, 2003

Recently we have constructed a mechanistic model describing the nitroxide mediated miniemulsion p... more Recently we have constructed a mechanistic model describing the nitroxide mediated miniemulsion polymerization (NMMP) of styrene at 135°C, using alkoxyamine initiators to control polymer growth (Nitroxide-Mediated Polymerization of Styrene in Miniemulsion. Modeling Studies of Alkoxyamine-Initiated Systems, 2001b). The model has since been expanded to describe styrene NMMP at 135°C using TEMPO and the free radical initiator, potassium persulfate (KPS). The

Archives of Oral Biology, 2008

Journal of Coatings Technology and Research, 2004

Living/controlled radical polymerizations provide significant advantages in the control of polyme... more Living/controlled radical polymerizations provide significant advantages in the control of polymer resin microstructure compared to conventional radical polymerization. Advances in our ability to tailor polymer microstructure will enable improvements in coatings properties and possible new applications of coating technologies. Adapting living radical polymerizations to heterogeneous media such as aqueous-based miniemulsion polymerization presents several challenges related to maintaining the livingness (the fraction of chains that are still “living” at the end of polymerization) of the polymer chains and also developing a commercially viable process. We have studied the nitroxide-mediated polymerization of styrene in miniemulsion, with the intent of maintaining a high degree of livingness by balancing the rates of biradical termination and disproportionation. We can now achieve >95% monomer conversion in less than three hours, while maintaining polydispersities ∼1.3. Monomer conversion can be dramatically increased from about 60–95% by changing the concentration of sodium dodecylbenzenesulfonate (SDBS) surfactant. Conversions in Dowfax 8390 stabilized miniemulsions showed no comparable dependency. Reasons for this potentially commercially important effect are under investigation.

arXiv (Cornell University), Nov 13, 2022

From hydrogels and plastics to liquid crystals, soft solids cover a wide array of synthetic and b... more From hydrogels and plastics to liquid crystals, soft solids cover a wide array of synthetic and biological materials 1 that play key enabling roles in advanced technologies such as 3D printing 2 , soft robotics 3 , wearable electronics 4 , self-assembly 5 , and bioartificial tissues 6, 7. Their elasticity and stimuli-induced changes in mechanical, optical, or electrical properties offer an unique advantage in designing and creating new dynamically functional components for sensing, micro-actuation, colour changes, information and mass transport. To harness the vast potential of soft solids through their ability to respond to the environment, a thorough understanding of their reactions when exposed to liquids is needed. Attempts to study the interactions between soft solids and liquids have largely focused on the wetting of soft solids 8-12 and its resulting deformation at equilibrium 12, 13 , in quasi-static state 14 , or in steady state 15, 16. Here we consider the frequently encountered case of unsteady wetting of a liquid on a soft solid, and show that transient deformation of the solid is necessary to understand unsteady wetting behaviours. We find that the initial spreading of the liquid occurs unin-1

A water droplet can bounce off superhydrophobic surfaces multiple times before coming to a stop. ... more A water droplet can bounce off superhydrophobic surfaces multiple times before coming to a stop. The energy loss for such droplet rebounds can be quantified by the ratio of the rebound speed UR and the initial impact speed UI , i.e., its restitution coefficient e = UR/UI . Despite much work in this area, there is still incomplete mechanistic explanation for the energy loss for rebounding droplets. Here, we measured e for sub-millimetric and millimetric sized droplets impacting two different superhydrophobic surfaces over a wide range of UI = 4–400 cm s−1. We proposed simple scaling laws to explain the observed non-monotonic dependence of e on UI . In the limit of low UI , energy loss is dominated by contact-line pinning and e is sensitive to the surface wetting properties, in particular to contact angle hysteresis Δcos θ of the surface. In contrast, in the limit of high UI , e is dominated by inertial-capillary effects and does not depend on Δcos θ.

Soft Matter

Viscous droplets impinging on soft substrates may exhibit several distinct behaviours including r... more Viscous droplets impinging on soft substrates may exhibit several distinct behaviours including repeated bouncing, wetting, and hovering, i.e., spreading and retracting after impact without bouncing back or wetting.

Facing shortages of personal protective equipment, some clinicians have advocated the use of barr... more Facing shortages of personal protective equipment, some clinicians have advocated the use of barrier enclosures (typically mounted over the head, with and without suction) to contain aerosol emissions from coronavirus disease 2019 (COVID-19) patients. There is however little evidence for its usefulness. To test the effectiveness of such a device, we built a manikin that can expire micron-sized aerosols at flow rates close to physiological conditions. We then placed the manikin inside the enclosure and used a laser sheet to visualize the aerosol leaking out. We show that with sufficient suction, it is possible to effectively contain aerosol from the manikin even at high flow rates (up to 60 L min−1) of oxygen, reducing aerosol exposure outside the enclosure by 99%. In contrast, a passive barrier without suction only reduces aerosol exposure by 60%.

IOP Conference Series: Materials Science and Engineering, 2017

A new multi-chamber rotary compressor (MCRC) has been designed and the simulation result is prese... more A new multi-chamber rotary compressor (MCRC) has been designed and the simulation result is presented in this paper. MCRC utilizes the space within the cylinder and it has the advantage of being more compact. Mathematical models which include geometrical, thermodynamics, mass flow and discharge valve have been formulated to evaluate the performance of MCRC. Parametric studies have also been carried out to determine the effects of design parameters such as suction and discharge ports size, valve length, valve thickness and valve width on compressor performance. In this paper, mathematical models will be presented and the predictions of the model will be shown and discussed.

IOP Conference Series: Materials Science and Engineering, 2017

A new multi-chamber rotary compressor (MCRC) is introduced in this paper. This new compressor is ... more A new multi-chamber rotary compressor (MCRC) is introduced in this paper. This new compressor is designed for compactness and energy efficient, with potential applications in refrigeration systems. In this paper, the design of the new compressor will be presented. Various components and their functions together with the overall advantages will be shown and discussed. In its basic form, it is a rotary compressor with two chambers working simultaneously to increase its output by maximizing the available working space and hence reduces material usage. The basic working principles will also be discussed and its advantages will be presented in comparison with other existing rotary compressors.

Polymer, 2005

Recent efforts to adapt nitroxide-mediated living radical polymerization chemistry to colloidal s... more Recent efforts to adapt nitroxide-mediated living radical polymerization chemistry to colloidal systems have shown considerable progress when miniemulsions are used. Miniemulsion SFRP in fact can yield higher conversions (O99%) and faster reaction rates than bulk SFRP. Much of the advantage of operating in miniemulsion arises from the inherent advantages of having a two phase system, in which the aqueous phase can be employed as a medium to introduce rate enhancing additives such as ascorbic acid to the reaction loci with a high degree of control. Additives such as ascorbic acid act by consuming excess nitroxide, and therefore directly influence the rate. Results on the effect of ascorbic addition on rate, molecular weight and livingness are presented. We have also begun to address the issue of high operating temperatures in TEMPO-mediated SFRP (w120-135 8C) that require a pressurized reactor. We have run experiments using TEMPO at 100 8C with slowly decomposing initiator added to maintain an appropriate free nitroxide concentration. Reasonable reaction rates are obtained, albeit with higher polydispersities (w1.6). Challenges and opportunities related to lower temperature operation are discussed.

Macromolecular Symposia, 2004

Nitroxide‐mediated living radical polymerizations of styrene were run in miniemulsion. Using a mo... more Nitroxide‐mediated living radical polymerizations of styrene were run in miniemulsion. Using a modified miniemulsion process that does not require the use of a volatile costabilizer, near complete conversions could be achieved in 2‐3 hours while preserving narrow molecular weight distributions and a high degree of chain livingness. Increased rates and final conversions were achieved by semi‐batch addition of the nitroxide scavenger ascorbic acid.

Journal of Polymer Science Part A: Polymer Chemistry, 2002

The rate‐accelerating effects of camphorsulfonic acid (CSA) on nitroxide‐mediated styrene miniemu... more The rate‐accelerating effects of camphorsulfonic acid (CSA) on nitroxide‐mediated styrene miniemulsion polymerization were studied. Polymerizations were initiated with benzoyl peroxide (BPO) as an initiator and mediated with either 2,2,6,6‐tetramethylpiperidinyloxy (TEMPO) or 4‐hydroxy‐2,2,6,6‐tetramethylpiperidinyloxy (OH‐TEMPO). Although CSA has been used to accelerate the rate in bulk nitroxide‐mediated polymerizations, it has not been well studied in emulsion/miniemulsion. With dispersed systems, the effectiveness of CSA is likely to be affected by partitioning between the aqueous and organic phases. In styrene miniemulsion experiments performed over a range of conditions, the effect of adding CSA varied from negligible to significantly increasing the final conversion and molecular weight, depending on the nitroxide:BPO ratio. At a ratio of nitroxide:BPO = 1.7, the effect of CSA addition is small, whereas the final conversion and molecular weight are dramatically enhanced by CSA...

Journal of Polymer Science Part A: Polymer Chemistry, 2006

Skip to Main Content. Wiley Online Library will be disrupted 3 Sep from 10-12 BST for monthly mai... more Skip to Main Content. Wiley Online Library will be disrupted 3 Sep from 10-12 BST for monthly maintenance. ...

Chemical Engineering Science, 2003

Recently we have constructed a mechanistic model describing the nitroxide mediated miniemulsion p... more Recently we have constructed a mechanistic model describing the nitroxide mediated miniemulsion polymerization (NMMP) of styrene at 135°C, using alkoxyamine initiators to control polymer growth (Nitroxide-Mediated Polymerization of Styrene in Miniemulsion. Modeling Studies of Alkoxyamine-Initiated Systems, 2001b). The model has since been expanded to describe styrene NMMP at 135°C using TEMPO and the free radical initiator, potassium persulfate (KPS). The

Archives of Oral Biology, 2008

Journal of Coatings Technology and Research, 2004

Living/controlled radical polymerizations provide significant advantages in the control of polyme... more Living/controlled radical polymerizations provide significant advantages in the control of polymer resin microstructure compared to conventional radical polymerization. Advances in our ability to tailor polymer microstructure will enable improvements in coatings properties and possible new applications of coating technologies. Adapting living radical polymerizations to heterogeneous media such as aqueous-based miniemulsion polymerization presents several challenges related to maintaining the livingness (the fraction of chains that are still “living” at the end of polymerization) of the polymer chains and also developing a commercially viable process. We have studied the nitroxide-mediated polymerization of styrene in miniemulsion, with the intent of maintaining a high degree of livingness by balancing the rates of biradical termination and disproportionation. We can now achieve >95% monomer conversion in less than three hours, while maintaining polydispersities ∼1.3. Monomer conversion can be dramatically increased from about 60–95% by changing the concentration of sodium dodecylbenzenesulfonate (SDBS) surfactant. Conversions in Dowfax 8390 stabilized miniemulsions showed no comparable dependency. Reasons for this potentially commercially important effect are under investigation.