I do not see anything wrong with Muslim men wearing neckties, because the necktie is no longer a distinguishing mode of dress for the unbelievers. It is now a part of the Muslims’ dress in many Muslim countries like Egypt, Syria, Iraq, and Morocco...etc. Therefore, the purpose of forbidding it does not exist. Even if it is something that originated among non-Muslims, anything that becomes global ceases to belong to any specific civilization.
It is not permissible for men to wear a necktie made of silk. Silk is forbidden for men, whether worn direct on the body, around the neck, or over the head. All of these are different ways of wearing something.
The Prophet (peace be upon him) took a piece of silk in his right hand and a piece of gold in his left, held them aloft, and said: “These are forbidden for the men of my people and permitted for the women.” [Sunan Ibn Mâjah]
The Prophet (peace be upon him) also said: “Gold and silk have been permitted for the women of my people and forbidden for the men.”
The Prophet (peace be upon him) issued the following stern warning to Muslim men: “Silk is only worn in this world by one who will have no share of the pleasure of the Hereafter.” [Sahîh al-Bukhâri and Sahîh Muslim]
He also said: “Whoever wears silk in this world will not wear it in the Hereafter.” [Sahîh al-Bukhâri]
Men are alowed to wear silk only under special circumstances. They may wear silk uniforms in times of war in order to show off and intimidate the enemy, which is a kind of psychological warfare.
People who are suffering from skin diseases may wear silk to relieve their suffering. The Prophet (peace be upon him) allowed ‘Abd al-Rahmân ibn ‘Awf and Ibn al-Zubayr to wear silk when they were suffering from scabies. [Sahîh al-Bukhâri and Sahîh Muslim]
And Allah knows best.