Doc Brown's Chemistry Revision Notes - Smart Materials and Materials Science

Part 3 SHAPE MEMORY POLYMERS, pH and temperature sensitive-responsive polymers, Self-healing materials


ALPHABETICAL LIST of materials, effects etc. mentioned on these pages: Smart Materials Science INDEX * CARBON FIBRES * CHROMOGENIC MATERIALS * ELECTROCHROMIC MATERIALS * GORETEX * HALOCHROMIC MATERIALS  * HIGH PERFORMANCE POLYMERS * KEVLAR * LYCRA * MAGNETIC SHAPE MEMORY ALLOYS * MAGNETOSTRICTIVE MATERIALS * NITINOL * pH SENSITIVE POLYMERS * PHOTOCHROMIC MATERIALS * PHOTOMECHANICAL MATERIALS * PIEZO ELECTRIC EFFECT-MATERIALS * PTFE * SELF-HEALING MATERIALS * SHAPE MEMORY ALLOYS * SHAPE MEMORY POLYMERS * SPANDEX * TEFLON * TEMPERATURE-RESPONSIVE POLYMERS * THERMOCHROMIC MATERIALS * THINSULATE *


PART 3 SHAPE MEMORY POLYMERS (plastics), pH and temperature sensitive-responsive polymers


Part 3a. SHAPE MEMORY POLYMERS

  • These are organic (usually) polymer materials in which deformation (change in shape) can be induced and recovered through temperature changes or stress changes.

  • Shape memory polymers (SMPs) are another example of scientists trying to design 'intelligent' and 'self-repairing' materials e.g. like the development of high performance polymers and shape memory alloys.

  • Thermally induced shape memory materials (like shape memory alloys, SMA) are easy to manufacture but cheaper than SMAs.

    • The basic principles of manufacture are as follows e.g. for an implant for some minimal invasive surgery procedure

      • The polymer is made and procured into the permanent shape by conventional polymerisation and processing technology.

      • This is followed by the 'programming' process which involves either (a) heating sample to deform, cooling below transition temperature, or (b) directly deforming SMP device at room temperature.

      • This then 'programmes' the polymer device to achieve its desired when activated on reaching the transition temperature.

      • Summarising ...

      • (i) polymer made into the SMP's permanent shape at 37oC e.g. [=]

      • (ii) the SMP device compressed into temporary shape at room temperature (20-25oC) e.g. <->

      • (iii) the SMP device undergoes transition to the required permanent shape at 37oC e.g. back to [=]

  • They are used in minimal invasive surgery procedures.

    • This can be achieved with stimuli sensitive implant materials.

    • Degradable implants could be inserted into the body in a compressed (temporary) shape, through a small incision, where they obtain the desired final relevant shape for the particular situation after warming up to body temperature i.e. the SMP device has a transition temperature above room temperature (operating theatre temperature) but below the body temperature of 37oC e.g. 35-37oC.

      • After some time, the implant, can be designed to then degrade away!

  • SMPs have applications in high performance textiles.

  • Self-repairing plastic components in technical devices.


Part 3b. pH-SENSITIVE POLYMERS

  • pH-sensitive polymers are materials which can swell (by absorbing water?) when the pH of the surrounding aqueous (water based) media changes.

  • The effect is reversible with change in pH in the opposite direction to contract or collapse the material (i.e. loses water?).


Part 3c. TEMPERATURE-RESPONSIVE POLYMERS

  • Temperature-responsive polymers are materials which undergo changes if the temperature changes.

  • This is essentially a response to a cooling or heating stimulus.


Part 3d. SELF-HEALING MATERIALS

  • Self-healing materials have the natural ability to repair damage due to normal usage and so increase the material's useful lifetime

WHERE NEXT?

INDEX of SMART MATERIALS PAGES

PART 1 CHROMOGENIC MATERIALS - Thermochromic, Photochromic & Electrochromic Materials

PART 2 SHAPE MEMORY ALLOYS e.g. Nitinol & Magnetic Shape Memory Alloys

PART 3 SHAPE MEMORY POLYMERS, pH and temperature sensitive-responsive polymers, Self-healing materials

Part 4 LYCRA-SPANDEX

PART 5 High performance polymers like KEVLAR

PART 6 GORETEX, THINSULATE and TEFLON-PTFE

PART 7 PIEZOELECTRIC EFFECT (PIEZOELECTRIC MATERIALS) and PHOTOMECHANICAL MATERIALS

PART 8 CARBON FIBRES

See also INDEX NANOSCIENCE-NANOCHEMISTRY pages

Nanomaterials including carbon nanotubes, carbon fibres and silver nanoparticles are on a separate page

More on chemistry applications: Uses of 220+ chemical elements, compounds, mixtures & Formulation chemistry

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