Clip connector

Hard matter clips – crystolecles & macroscale

• Macroscale: plastic, metals, wood, …
• Nanoscale: crystolecules, genstone based structures

Structurally reversible and (less or more) structurally irreversible clip connectors

Structurally irreversible

Clip connectors can come with hook like barbs that do not allow to pull them back out.
And if there is no access to these barbs and
there are no suitable tools available to bend them back then the connection is structurally irreversible.
★ The parts can't be recomposed to other configurations
★ Broken parts (so far one can identify them) can't replaced reusing the other parts already connected to them.

One reason to go for such barbed clips is to … ★ not just make sure that the don't come out by accident (more on that later) but to
★ get a significant fraction of the total material strength in the loading direction.
… but then one might want to go all the way to fir tree joints that maximize on material strength retainment better than mere dovetail joints (what barbed clips usually constitute).

One reason to not go for such barbed clips
(beside the potential structural irreversibility and consequences described above)
is that the stiffness of the connection is hard to control.
A bit too tight and it does not work a bit too loose and there is very low stiffness of the connection
Likely more an issue for nanoscale than macroscale.

Even without barbs if clips can't be latched on with enough force
(by for closure or some form of attraction force)
they still are effectively structurally irreversible.
Think surface flush pin without flat small head.

Structurally reversible

Avoiding back hooking barbs the clip can always be removed along the same path it was inserted
with some amount of force much below the material strength.
★ This is not adequate if one wants high loads in the clipping direction
★ but totally adequate if one wants low loads if the intent is just to make sure the clip does not come out by accident.
In the latter case one can still support high loads by using the clip just for positive locking
as a one step indirection by form closure.

Clips that do not rely on bending and shape interference (form closure that can be bent away)
but rely on other forces like vdW forces are all structurally reversible
so far they can be latched on from the insertion side with available tools.

Energetically reversible and (less or more) energetically irreversible clip connectors

For reasons (noted further below) one might usually associate clips with energetically irreversibility
but Clips do not necessarily mean snaps in the sense of making sound and heat dissipating some energy.
(Snaps as defined on page: Intercrystolecular snapping modes)
Clips can in principle to a be actuated reversibly by doing energy recuperation.

That extended association to "energetic reversible clips" might not come natural
as is does not preserve the sharp sound imitating onomatopoeia aspect
"clip" "click" "snap" "zapp" (also related to the kiki bouba effect)

(wiki-TODO: Decided against for now: Maybe split the page in two dividing the concepts? Energy dissipative clips & reversible ones.)

Types of (crystolecule based) clip connectors

★ Classical clips that provide an energy barrier against reopening by larger scale mechanical bending
★ Clip connectors that use some other force to provide the energy barrier against accidental reopening
… particularly vdW forces at the nanoscale

The latter may stretch the concept of clips a bit but it will be included here and on this wiki.

Barrier against reopening over size of the clip

Even very small crystolecule clips already have such high activation energy barriers that FAPP
random thermal fluctuations are not capable of accidentally open them up anymore.
Even if there a many mols worth of such snap connectors present and observed over a very long time like millenia or far above that even.
This does not only hold for the bending type clips
but even for the vdW force clips too.

(TODO: Add some simple math here. Arhenius & Eyering equations.)

So usually there is no risk or thermal motions accidentally opening up even the smallest of crystolecule clips.
Holding chains together by weaker clips that merely use VdW force
can already fully suffice to guard against disassembly by thermal motion.

VdW froce clip accidental reopening risk factors

There is an other mechanism that has enough energy to open up the weaker vdW clips by accident though. That is the crystolecule newton's cradle effects.

Accumulating trapped charges charges of same size may be a risk factor too.
But one should probably design against such charges. Especially during the assembly process
after which many temporary vdW connections might be secured by form closure atop.

It can still make sense to guard against these failure modes.
One way to do that is to go for form closure.
This just shifts the problem, yes, but it also allows to gather the problem together
up to larger scales where there is enough space for much stronger clips.
Gather linearly or hierarchically (=exponentially).

One particular approach to guard against accidental clip reopening from the stronger non-thermal effects
(= accidental disassembly damage mechanisms)
is the idea of shape locking chains that make for sequential form closure.
Due to form closure only the part (possibly single crystolecule) added last can be removed first.
Last in first out assembly. LIFO assembly.

Energy recuperation by avoiding bend-snaps

Nanoscale crystolecule clips could be designed such
that they allow energy recuperation.
This may allow for notable increase in speed in
the recomposition of crystolecues and microcomponents.

Same for VdW suck-in slide naps. Next section.

Energy recuperation by avoiding slide-snaps

Rather than allowing for a sperlubric free-wheeling slide-snap that rattle and heat everything up:
Provide a counterforce and recuprate large parts of the vdW binding energy change during assembly.

Foldamers (e.g. de-novo proteins)

Snap-together by mere touching

Energetic snap-together by shape complementarity hydrogen bonding and VdW forces is natural and obviously worth to go for.
See Van der Waals force sticking and VdW suck-in.

Related page: Intercrystolecular snapping modes

Clipping

The idea is to clip foldamers together using larger scale elastic deformation.
Te result would be is a form closure connection that may or may nor be energetically and/or structurally reversible re-openable.

Questionable benefits

Such a connection might have slightly higher mechanical stability than a mare surface contact snap-together.
But likely not by much, since internal cohesion of proteins is also not providing dense a polycyclic covalent network.
Unless the protein backbone has been heavily covalently cross-linked, which is difficult.

Potential challenges

Clips need active force applying actuation. That means:

• thermally driven selfassembly is no longer an option (a huge loss) and
• some form of positional assembly is needed. Either bottom up positional assembly or top down positional assembly

For proteins to reach around parts of other proteins (like a clamp) such that they are not only shape complementary but also can do large scale deformation clipping actions, they need to be quite large (quite far into tertiary structure). This may make de-novo protein engineering harder.

Alternatives to reach higher bonding strengths between de-novo proteins include:

• covalent cross-linking after quaternary assembly

Related to de-novo protein clipping

The folded-foldamer pushing approach.

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Empolying extensive form closure assembly and rebar-style-tensionsing not only in advaned gemstone based nanosystems but already in earlier foldamer based nanosystems.

This likely is not sensible is seems due to proteins being to soft rough and sticky.
Even de-novo proteins specifically enginnered to be stiff and of simple shape.

See: RepRec pick and place robots and ReChain frame systems

Related

• Snapback
• VdW suck-in
• Brownian ratchet
• Connection methods
• Intercrystolecular snapping modes – clips do not necessarily mean snaps – see page: Energy recuperation

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Clips in positive locking mechanisms in systems and subsystems. Some related projects:

• ReChain frame systems & ReChain index page
• RepRec pick-and-place robots

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• Design principle of passive pretension

External links

• Wikipedia: Brownian ratchet