Characterization of Graft-Modified Porous Polymer Membranes

Hautojärvi, Joni; Kontturi, Kyösti; Näsman, Jan H.; Svarfvar, Bror; Viinikka, P.; Vuoristo, Mikko

doi:10.1021/ie950223b

Cited by 61 publications

(63 citation statements)

References 26 publications

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“…It has been experimentally observed that the hydraulic permeability of a poly(acrylic acid)-grafted porous poly(vinylidene fluoride) membrane changed by three orders of magnitude with pH, while the diffusional permeability changed by only a factor of 2.4. 4 Conformation changes of the graft polymer could have a stronger effect on hydraulic permeability because flow rate is proportional to the fourth power of the pore radius, 13 while diffusional rate is only proportional to the square of pore radius. 15 Some theoretical studies on ionizable polymer brushes have been conducted to correlate properties of the graft polymer chain, for example, brush height and degree of ionization, with the pH and ionic strength of the surrounding solution.…”

Section: Introductionmentioning

confidence: 99%

Temperature-responsive permeability of porous PNIPAAm-g-PE membranes

Peng

Cheng

1998

J. Appl. Polym. Sci.

116

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ABSTRACT:Grafting a temperature-responsive polymer, poly(N-isopropylacrylamide) (PNIPAAm), onto porous polyethylene (PE) membranes by UV irradiation was investigated. A wide range of graft yields (5-449%) was achieved by varying irradiation time (20 -240 min) and monomer concentration (1.2-3.6 wt %). Characterization by XPS and SEM shows that the graft polymers are located both on the external surfaces as well as inside the pores of the membranes. Diffusional permeation experiments show that two distinct types of temperature responses were observed, depending on the graft yield; permeability increases with temperature in low graft yield membranes, while permeability decreases with temperature in high graft yield membranes. A mechanism explaining the dual valve functions of the graft membrane is proposed based on the location of the graft polymers on the membrane. It was also observed the permeability response exhibits a maximum with permeant molecular weight.

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Section: Introductionmentioning

confidence: 99%

Temperature-responsive permeability of porous PNIPAAm-g-PE membranes

Peng

Cheng

1998

J. Appl. Polym. Sci.

116

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“…This method has been shown to control the reaction and to obtain high densities of surface-grafted polymer. 25 Several surface 'grafting from' techniques have been reported in the literature, including chemical grafting, 25 plasma, 24,26 radiation 13,19,27,28 and photoinduced grafting. 29,30 A previously reported plasma-induced grafting technique 24 was chosen for the grafting of PNIPAM to the PCTEPMs because it presented several advantages to incorporating the desired properties into the PC membrane.…”

Section: Synthesis Pathway To Incorporate Pnipam Into Pctepmsmentioning

confidence: 99%

“…13,26,30,38 Switching responses with a bigger change in pore sizes, from 50 to 200 nm, have been achieved using hydrogels; however, these systems present very long response times. 39 Permeability switching experiments in response to light The experimental setup and pore size calculations (Hagen-Poiseulle) used for the thermal switching experiments were also used for the light-induced permeability changes in the synthesized NPCgPCTEPMs (Figure 6a).…”

Section: Synthesis Pathway To Incorporate Pnipam Into Pctepmsmentioning

confidence: 99%

“…This technique allows for rapid 'on/ off' switching and flow control because it synergizes the chemical stability and mechanical strength of the polymer membrane with the fast response times of the free-ended polymer chains chemically bonded to them. As a result, different composite membranes, capable of changing their effective pore size with environmental triggers, such as pH and ionic strength, 13,14 temperature, 15 chemical moieties, such as glucose, 16 and more recently, light, [17][18][19] have been developed.…”

Section: Introductionmentioning

confidence: 99%

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Bioinspired synthesis of optically and thermally responsive nanoporous membranes

Morones‐Ramírez

2013

NPG Asia Mater

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The development of porous membranes that can rapidly change flow rates in response to external, noninvasive stimuli has broad technological applications for areas ranging from biomedical devices to architecture. Environmentally responsive membranes have a fundamental role in the development of devices used in chemical sensors, biological sorters, sequencing, separations, high-throughput medical devices and labs on a chip. The design and engineering of these responsive porous membranes have been achieved through the coupling of porous membranes with polymeric materials that can change their physical conformation in response to pressure, heat, pH or different chemical entities. Inspired by the phototropic growth of coleoptiles and the light-mediated mechanism that plants use to open their stomata, in this work, light-responsive porous membranes were engineered, mathematically modeled and synthesized. This biologically inspired approach led to a state-of-the-art design technique and a device that outperforms its natural counterpart and is capable of reversibly controlling flow rates from 0.001 to 0.035 ml s À1 cm À2 in less than a few minutes using the noninvasive stimulus of light. We envision that the polymeric responsive membranes and the platform synthesis technique employed in this manuscript for their fabrication could be utilized in a broad range of applications and will have a great impact on the fields of fluid handling, biomedical high-throughput devices, sensors, medicine and other fields of chemistry, biology and mechanical engineering.

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“…These movable membranes are further coupled to magnetic, piezoelectric or pressure actuated methods which allow external switching. Some examples of mechanical actuators include permeable membranes (Hautojarvi et al, 1996;Kontturi et al, 1996;Ulbricht, 1996;Peng and Cheng, 1998;Peng and Cheng, 1999;Peng and Cheng, 2001;Chu et al, 2003;Gatimu et al, 2006), and nanofabricated reservoirs that act as constant sources of reagents (Groisman et al, 2005;Frevert et al, 2006;Keenan et al, 2006).…”

Section: Types Of Actuators That Control Flowmentioning

confidence: 99%

Environmentally responsive polymeric "intelligent" materials: the ideal components of non-mechanical valves that control flow in microfluidic systems

Morones‐Ramírez¹

2010

Braz. J. Chem. Eng.

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-Miniaturization and commercialization of integrated microfluidic systems has had great success with the development of a wide variety of techniques in microfabrication, since they allowed their construction at a low cost and by following simple step-series procedures. However, one of the major challenges in the design of microfluidic systems is to achieve control of flow and delivery of different chemical reagents. This feature is especially important when using microfluidic systems in the development of cell culture systems, the construction of labs on a chip and the fabrication and design of chemical microreactors. Spatiotemporal control of the microenvironment in microfluidic devices has been only partially achieved by incorporating actuator parts (mechanical and non-mechanical) within these devices; nevertheless, recently there has been enormous progress due to advances in the materials sciences, and the development of novel polymeric "intelligent" materials. These materials have proved to be excellent candidates in the construction of non-mechanical actuators in the form of environmentally responsive valves. These valves can more efficiently control flows because these "intelligent" materials are capable of undergoing conformational changes and phase transitions in response to different local or external environmental stimuli; allowing them to turn the valves from "on" to "off". In addition, these valves have very simple designs, and are easy and cheap to incorporate into microfluidic systems. Therefore, although there are many reviews that focus on the development and design of non-mechanical actuators, the following review proceeds to describe the exciting characteristics, potential uses and synthesis methods of the building blocks of the most recent and innovative non-mechanical valves, environmentally responsive polymeric "intelligent" materials. In addition, the last section of this review will focus on the synthesis of composite materials that are capable of responding to more than one type of stimulus, since these materials are believed to be the future components that will boost the development of microfluidic systems with spatiotemporal controlled microenvironments.

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Characterization of Graft-Modified Porous Polymer Membranes

Cited by 61 publications

References 26 publications

Temperature-responsive permeability of porous PNIPAAm-g-PE membranes

Temperature-responsive permeability of porous PNIPAAm-g-PE membranes

Bioinspired synthesis of optically and thermally responsive nanoporous membranes

Environmentally responsive polymeric "intelligent" materials: the ideal components of non-mechanical valves that control flow in microfluidic systems

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